SIST ISO 11041:1997
(Main)Workplace air -- Determination of particulate arsenic and arsenic compounds and arsenic trioxide vapour -- Method by hydride generation and atomic absorption spectrometry
Workplace air -- Determination of particulate arsenic and arsenic compounds and arsenic trioxide vapour -- Method by hydride generation and atomic absorption spectrometry
Gives a method by hydrid generation for the atomic absorption spectrometric determination of the mass concentration of particulate arsenic, arsenic compounds and arsenic trioxide vapour in workplace air. Applicable to the determination of mass concentrations of approximately 100 ng to 125 g of arsenic per sample. Not suitable for the determination of arsenic in the form of metal arsenides.
Air des lieux de travail -- Dosage de l'arsenic particulaire, des composés particulaires de l'arsenic et des vapeurs de trioxyde d'arsenic -- Méthode par production d'hydrures et spectrométrie d'absorption atomique
Zrak na delovnem mestu - Ugotavljanje arzenovega prahu, arzenovih spojin in plinastega arzenovega trioksida z metodo generiranja hidrida in atomsko absorpcijsko spektrometrijo
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IS0 11041:1996(E)
Foreword
IS0 (the International Organization for Standardization) is a worldwide
federation of national standards bodies (IS0 member bodies). The work of
preparing International Standards is normally carried out through IS0
technical committees. Each member body interested in a subject for
which a technical committee has been established has the right to be
represented on that committee. International organizations, governmental
and non-governmental, in liaison with ISO, also take part in the work. IS0
collaborates closely with the International Electrotechnical Commission
(IEC) on all matters of electrotechnical standardization.
Draft International Standards adopted by the technical committees are
circulated to the member bodies for voting. Publication as an International
Standard requires approval by at least 75 % of the member bodies casting
a vote.
International Standard IS0 11041 was prepared by Technical Committee
lSO/TC 146, Air quality, Subcommittee SC 2, Workplace atmospheres.
Annex A of this International Standard is for information only.
0 IS0 1996
All rights reserved. Unless otherwise specified, no part of this publication may be
reproduced or utilized in any form or by any means, electronic or mechanical, including
photocopying and microfilm, without permission in writing from the publisher.
International Organization for Standardization
Case Postale 56 l CH-1211 Geneve 20 l Switzerland
Printed in Switzerland
ii
---------------------- Page: 1 ----------------------
IS0 11041:1996(E)
INTERNATIONAL STANDARD @ IS0
Workplace air - Determination of particulate arsenic and arsenic
compounds and arsenic trioxide vapour - Method by hydride
generation and atomic absorption spectrometry
WARNING - Arsenic and arsenic compounds are toxic and are recognized as human carcinogens (see reference
[I] in annex A). Avoid any exposure by inhalation. Personal protection (e.g. an effective respirator) must be used
in all cases where exposure to arsenic or arsenic compounds is possible.
this International Standard. At the time of publication,
1 Scope
the editions indicated were valid. All standards are
subject to revision, and parties to agreements based
This International Standard specifies a method for the
on this International Standard are encouraged to in-
determination of the mass concentration of particulate
vestigate the possibility of applying the most recent
arsenic and arsenic compounds and arsenic trioxide
editions of the standards indicated below. Members
vapour in workplace air, using either continuous-flow
of IEC and IS0 maintain registers of currently valid
hydride generation or flow-injection-analysis hydride
International Standards.
generation and atomic absorption spectrometry. The
method is not suitable for determination of arsenic in
the form of metal arsenides which decompose in the IS0 648:1977, Laboratory glassware - One-mark
presence of water or acid (see 10.1). pipettes.
The method is applicable to the determination of
IS0 1042: 1983, Laboratory glassware - One-mark
masses of approximately 100 ng to 125 pg of arsenic
volumetric flasks.
per sample, for analysis of test solutions prepared
using sample solution aliquots in the recommended
IS0 3585: 1991, Borosilicate glass 3.3 - Properties.
range (see 9.3.2). The concentration range for arsenic
in air, for which this procedure is applicable, is deter-
IS0 3696: 1987, Water for analytical labora tory use -
mined in part by the sampling procedure selected by
Specification and test methods.
the user.
IS0 6955: 1982, Analytical spectroscopic methods -
The method is applicable to personal and fixed-
Flame emission, atomic absorption and atomic
location sampling.
fluorescence - Vocabulary.
A number of transition metals may interfere with the
IS0 7708:1995, Air quality - Particle size fraction
determination of arsenic by hydride generation and
definitions for health-related sampling.
atomic absorption spectrometry (see 10.3)
IS0 8655-l :-I), Piston and/or plunger opera ted
volumetric apparatus (POVA) - Part 1: Definitions.
2 Normative references
I SO 8655-2:--l 1, Piston and/or plunger opera ted
volumetric apparatus (POVA) - Part 2: Operating
The following standards contain provisions which,
considerations.
through reference in this text, constitute provisions of
1) To be published.
1
---------------------- Page: 2 ----------------------
0 IS0
IS0 11041:1996(E)
Piston and/or plunger opera ted charge lamp, and it is heated either electrically or by
IS0 8655-3:-l),
an oxidizing air/acetylene flame.
volumetric apparatus (POVA) - Part 3: Methods of
test.
NOTE 2 This International Standard describes the use of
two types of hydride generation system. Continuous flow
IS0 8655-4:-l), Piston and/or plunger opera ted
systems function by pumping a continuous stream of test
volumetric apparatus (POVA) - Part 4: Specifications.
solution to the mixing piece, and such systems generate a
constant atomic absorption signal. Flow injection analysis
IS0 8756: 1994, Air quality - Handling of tempera-
systems inject a discrete volume of test solution, and
ture, pressure and humidity data.
produce a transient atomic absorption signal.
EN 482: 1994, Workplace atmospheres - General
3.5 Absorbance measurements are made at
requirements for the performance of procedures for
197,2 nm or 193,7 nm, and results are obtained by the
the measurement of chemical agents. EN 482, CEN,
analytical-curve technique (see IS0 6955: 1982, sub-
Brussels, Belgium (1994).
clause 6.1 .I ), or the analyte addition technique (see
IS0 6955:1982, subclause 6.1.3).
EN 1232: --I), Workplace atmospheres - Pumps for
personal sampling of chemical agents - Require-
ments and test methods.
4 Reactions
3 Principle
4.1 In most workplace situations where exposure to
arsenic can occur (e.g. in the refining of base metals,
3.1 Particulate arsenic and arsenic compounds and
welding and other hot metal processes) a significant
arsenic trioxide vapour are collected by drawing a
proportion of the arsenic is present in the form of
measured volume of air through a cellulose ester
arsenic trioxide vapour (see reference [3] in annex A).
membrane filter and a back-up paper pad impregnated
This vapour is collected by reaction with sodium
with sodium carbonate and mounted in a sampler de-
carbonate on an impregnated back-up paper pad.
signed to collect the inhalable fraction of airborne par-
ticles.
As,O, + Na,CO, -+ ZNaAsO, + CO,
3.2 The cellulose ester membrane filter, back-up
4.2 The majority of arsenic compounds which are
paper pad and collected sample are wet-ashed using
commonly found in samples of workplace air are con-
nitric acid, sulfuric acid and hydrogen peroxide. The
verted to soluble arsenate ions (As0,3-) by the wet-
nitric acid and hydrogen peroxide are removed by
ashing procedure specified in 8.2.2. However, if there
boiling on a hotplate until dense, white fumes of sulfur
is any doubt about the effectiveness of this procedure
trioxide are evolved, and the sample solution is then
for dissolution of particulate arsenic compounds which
allowed to cool and diluted to a given volume with
could be present in the test atmosphere, investigate
water.
before proceeding with the method (see 10.2).
NOTE 1 The wet-ashing procedure specified in 8.2.2 is
based upon a NIOSH procedure (see reference [2] in annex
A) which has been modified to avoid taking the sample
4.3 Prior to hydride generation (see 4.4) arsenate
solution to dryness.
ions (AsO,s-) are reduced to arsenite ions (AsO,-) by
reaction with potassium iodide (see 8.2.4).
3.3 A test solution is prepared by transferring an
aliquot of the sample solution to a volumetric flask,
AsOds- + Zl- + 4H+ + AsO,- + I2 + 2H,O
together with appropriate volumes of dilute sulfuric
This reduction is necessary since pentavalent arsenic
acid, concentrated hydrochloric acid and potassium
gives a lower analytical response than trivalent arsenic
iodide solution, and diluting to volume with water.
because it is less rapidly converted to arsine.
3.4 The test solution is reacted with sodium tetra-
hydroborate solution in a continuous-flow hydride
generation system or flow-injection-analysis hydride
4.4 Hydride generation occurs as a result of the
generation system to liberate arsine and hydrogen.
reaction between trivalent arsenic and nascent hydro-
These gaseous products are separated from the
gen produced by the action of hydrochloric acid on
reaction liquid in a gas/liquid separator and carried by
sodium tetrahydroborate solution.
an inert purge gas into a silica or quartz absorption
cell. This absorption cell is mounted in the optical path
BH,- + H+ + 3H,O -+ H,BO, + 8H . . .
(1 >
of an atomic absorption spectrometer equipped with
an arsenic hollow cathode lamp or electrodeless dis- AsO,- + H+ + 6H + ASH, + 2H,O . . .
(2)
1) To be published.
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IS0 11041:1996(E)
@ IS0
5.6 Nitric acid (HNO$, concentrated,
4.5 Arsenic atoms are produced from arsine by the
- I,42 g/ml, 69 % (m/m) to 71 % (d.).
action of heat in a silica or quartz absorption cell,
P
heated either by a lean air/acetylene flame or elec-
The concentration of arsenic shall be less than
trically.
0,Ol pg/ml.
WARNING - Concentrated nitric acid is corrosive
5 Reagents
and oxidizing, and nitric acid fumes are irritant.
During the analysis, use only reagents of analytical Avoid exposure by contact with the skin or eyes,
or by inhalation of fumes. Personal protective
grade, and only water as specified in 5.1.
equipment (e.g. gloves, face shield or safety spec-
5.1 Water, complying with the requirements for
tacles, etc.) must be used when working with the
IS0 3696 grade 2 water (electrical conductivity less concentrated or diluted nitric acid, and concen-
than 0,l mS/m and resistivity greater than 0,Ol ML&m
trated nitric acid must be used in a fume hood.
at 25 “C).
5.7 Sulfuric acid (HzSOa), concentrated,
5.2 Sodium carbonate, 1 mol/l solution in 5 %
w I,84 g/ml, about 98 % (m/m).
P
glycerol solution.
The concentration of arsenic shall be less than
to a
Weigh IO,6 g of sodium carbonate (Na2C03) it 0,05 pg/ml.
and
250 ml beaker (6.2.1 .I). Add 5 ml of glycerol
WARNING - Concentrated sulfuric acid is corros-
50 ml of water (5.1) and swirl to dissolve. Quantita-
ive and causes burns. Avoid exposure by contact
tively transfer the solution to a 100 ml one-mark
with the skin or eyes. Personal protective equip-
volumetric flask (6.2.1.5) dilute to the mark with
ment (e.g. gloves, face shield or safety spectacles,
water, stopper and mix thoroughly.
etc.) must be used when working with the con-
centrated or diluted sulfuric acid. Fumes produced
5.3 Hydrochloric acid (HCI), concentrated
by heating concentrated sulfuric acid are irritant,
- 1 ,I8 g/ml, 35 % (m/m) to 36 % (m/m).
P
and this operation must therefore be carried out in
a fume hood. Caution must be exercised if adding
The concentration of arsenic shall be less than
water to sulfuric acid, since this reacts violently
0,Ol pg/ml.
with water (acid/water mixtures must be prepared
WARNING - Concentrated hydrochloric acid is
by adding acid to water).
corrosive, and hydrochloric acid vapour is irritant.
Avoid exposure by contact with the skin or eyes,
5.8 Hydrogen peroxide (HzO$, approximately
or by inhalation of fumes. Personal protective
30 % (m/m) solution.
equipment (e.g. gloves, face shield or safety spec-
tacles, etc.) must be used when working with the The concentration of arsenic shall be less than
concentrated or diluted hydrochloric acid, and 0,Ol pg/rnl.
concentrated hydrochloric acid must be used in a
WARNING - Hydrogen peroxide is corrosive and
fume hood. The vapour pressure of hydrochloric is
oxidizing. Avoid exposure be contact with the skin
high, therefore beware of pressure build-up in
or eyes. Personal protective equipment (e.g.
stoppered flasks when preparing acid/water
gloves, face shield or safety spectacles, etc.) must
mixtures.
be used when working with protective equipment
5.4 Hydrochloric acid, diluted 1 + 1. hydrogen peroxide.
Pour approximately 900 ml of water (5.1) into a 5.9 Potassium iodide, 100 g/l solution.
2 000 ml one-mark volumetric flask (6.2.1.5). Carefully
Weigh IO,0 g of potassium iodide (KI) into a 250 ml
add 1 000 ml of concentrated hydrochloric acid (5.3) to
beaker (6.2.1 .I ). Add 50 ml of water (5.1) and swirl to
the flask and swirl to mix. Allow to cool, dilute to the
dissolve. Quantitatively transfer the solution to a
mark with water, stopper and mix thoroughly.
100 ml one-mark volumetric flask (6.2.1.5) dilute to
NOTE 3 This is used as the solvent blank, as defined in the mark with water, stopper and mix thoroughly.
IS0 6955:1982, subclause 5.4.2, but in this International
Standard the solvent blank is referred to as the acid blank.
Prepare a fresh solution each month.
5.5 Hydrochloric acid, diluted 1 + 4.
5.18 Sulfuric acid, diluted 1 + 9.
Pour approximately 700 ml of water (5.1) into a Carefully add 25 ml of concentrated sulfuric acid (5.7)
1 000 ml one-mark volumetric flask (6.2.1.5). Carefully to 200 ml of water (5.1) in a 1 litre beaker. Swirl to
add 200 ml of concentrated hydrochloric acid (5.3) to
mix, allow to cool and quantitatively transfer to a
the flask and swirl to mix. Allow to cool, dilute to the
250 ml one-mark volumetric flask (6.2.1.5). Dilute to
mark with water, stopper and mix thoroughly.
the mark with water, stopper and mix thoroughly.
3
---------------------- Page: 4 ----------------------
IS0 11041:1996(E) @ IS0
5.11 Arsenic stock standard solution, correspond- ide (NaOH) pellets into a 1 litre beaker (6.2.1 .I). Add
ing to 1 000 mg of As per litre. 200 ml of water (5.1) and swirl to mix. Quantitatively
transfer the solution to a 1 000 ml one-mark volu-
511.1 Use a commercially available arsenic standard
metric flask (6.2.1.5) filtering through a membrane
solution at a concentration of 1 000 mg/l. Observe the
filter using a suction filtration apparatus (6.2.6). Dilute
manufacturer’s expiry date or recommended shelf-life.
to the mark with water (5.1) stopper and mix
thoroughly.
Alternatively, prepare an arsenic standard solution
according to the procedure specified in 5.11.2.
Prepare a fresh solution daily.
511.2 Accurately weigh 1,320 g + 0,001 g of arsenic NOTES
trioxide (As203) into a 50 ml beaker (6.2.1.1), add
4 Filtration of the solution is necessary to remove
10 ml of concentrated hydrochloric acid - (5.3), cover
undissolved particulate material which might otherwise
with a watch glass (6.2.1.2) and heat to approximately
cause clogging of the tubing or mixing piece of the hydride
150 “C on the hotplate (6.2.5) in a fume hood until dis-
generation system (6.2.8). The addition of alkali minimizes
solution is complete. Remove the beaker from the
hydrolysis of the sodium tetrahydroborate solution.
hotplate, allow to cool, quantitatively transfer the sol-
ution to a 1 000 ml one-mark volumetric flask (6.2.1.5)
5 A few drops of anti-foaming agent may be added to the
dilute to the mark with hydrochloric acid diluted 1 + 1
solution to reduce foaming in the gas/liquid separator of the
(5.4), stopper and mix thoroughly.
hydride generation system (6.2.8) which may result in a
noisy baseline signal.
This solution may be stored in a polypropylene bottle
6 The solution should be stored in a polypropylene bottle
(6.2.2) for up to one year.
(6.2.2) if it is not transferred to the reductant reservoir of
the continuous hydride generation system (6.2.8) immedi-
WARNING - Arsenic trioxide is toxic and is
ately after preparation (see 8.4.2.2). The top of the bottle
recognized as a human carcinogen (see reference
should not be fully tightened or pressure will build up due
[I] in annex A). See the general warning about
to the slow release of hydrogen.
arsenic or arsenic compounds, just after the title
of this International Standard.
5.15 Sodium hydroxide, 5 g/l solution.
5.12 Arsenic working standard solution A, corre-
Weigh 5,0 g of sodium hydroxide (NaOH) pellets into a
sponding to 10 mg of As per litre.
1 litre beaker (6.2.1 .I). Add 250 ml of water (5.1) and
swirl to dissolve. Quantitatively transfer the solution to
Using a pipette (6.2.1.3), accurately add I,00 ml of
a 1 000 ml volumetric flask (6.2.1.5) dilute to the mark
stock arsenic solution (5.11) to a 100 ml one-mark
with water, stopper and mix thoroughly.
volumetric flask (6.2.1.5) dilute to the mark with
hydrochloric acid diluted 1 + 1 (5.4) stopper and mix
5.16 Laboratory
detergent solution, suitable for
thoroughly.
cleaning samplers
and laboratory apparatus, diluted
with water (5.1)
according to the manufacturer’s
This solution may be stored in a polypropylene bottle
instructions.
(6.2.2) for up to one month.
5.17 Inert purge gas, for example argon or nitro-
5.13 Arsenic working standard solution B,
gen, supplied in a cylinder or as a cryogenic fluid.
corresponding to 1 mg of As per litre.
Using a pipette (6.2.1.3), accurately add 10 ml of 5.18 Air, compressed and filtered.
working arsenic solution A (5.12) to a 100 ml one-mark
NOTE 7 This gas is not required if the silica or quartz
volumetric flask (6.2.1.5), dilute to the mark with
absorption cell (6.2.9) used is electrically heated.
hydrochloric acid diluted 1 + 1 (5.4) stopper and mix
thoroughly.
5.19 Acetylene, in a cylinder.
This solution may be stored in a polypropylene bottle
NOTE 8 This gas is not required if the silica or quartz
(6.2.2) for up to one month.
absorption cell (6.2.9) used is electrically heated.
5.14 Sodium tetrahydroborate, solution corre-
sponding to between 2 g and 20 g of sodium tetra-
hydroborate per litre in 0,l mol/l sodium hydroxide
6 Apparatus
solution.
Prepare a sodium tetrahydroborate solution at the 6.1 Sampling equipment
concentration recommended by the manufacturer of
6.1.1 Samplers, for collection of the inhalable frac-
the hydride generation system (6.2.8). Weigh be-
tion of airborne particles (see 7.1 .I) as defined in
tween 2 g and 20 g of sodium tetrahydroborate
IS0 7708, suitable for use with the cellulose ester
(NaBHd) pellets or powder and 4 g of sodium hydrox-
4
---------------------- Page: 5 ----------------------
@ IS0 IS0 11041:1996(E)
membrane filters and back-up paper pads (6.1.2) and for several hours at room temperature. Store the
with the sampling pumps (6.1.3) used. paper pads impregnated with sodium carbonate in an
compatible
airtight container and use within one week of prep-
NOTES aration.
9 A number of different terms are used to describe sam-
NOTES
plers designed for collection of the inhalable fraction of air-
borne particles, for example, sampling heads, filter holders,
13 The volume of sodium carbonate solution required to
filter cassettes and air monitoring cassettes.
impregnate the back-up paper pads is typically 175 ~1 for a
25 mm diameter paper pad or 400 ~1 for a 37 mm diameter
10 In general, the collection characteristics of inhalable
paper pad.
samplers are such that particulate material collected on the
filter is the inhalable fraction of airborne particles, and any
14 The drying time for paper pads impregnated with
deposited on the internal surfaces of the sampler is not of
sodium carbonate may be reduced by placing them in an
interest. However, some samplers are designed such that
oven at 40 “C for 45 min.
airborne particles which pass through the entry orifice(s)
constitute the inhalable fraction; in which case any particu-
15 Glass-fibre or quartz-fibre filters impregnated with so-
late material deposited on the internal surfaces of the sam-
dium carbonate have also been shown to be efficient for
pler is part of the sample. Certain samplers of this type
collecting arsenic trioxide vapour (see reference [4] in annex
incorporate an internal filter cassette or cartridge which
A) and may be used as an alternative to cellulose ester
may be removed from the sampler to enable this material
membrane filters and back-up paper pads impregnated with
to be easily recovered.
sodium carbonate. Neither glass-fibre nor quartz-fibre filters
are dissolved by the wet-ashing procedure specified in
11 Samplers which are assembled by means of screw-
8.2.2, but this may be modified to permit their use (see
threaded fittings may be unsuitable for use with a cellulose
note 33).
ester membrane filter and a back-up paper pad. The high
restriction of a cellulose ester membrane filter, compared
6.1.3 Sampling pumps, complying with the require-
with that of a paper pad, means that there is a tendency for
ments of EN 1232, with an adjustable flow rate, incor-
air to take the path of least resistance and to be drawn
porating a flowmeter or a flow-fault indicator, and
along screw threads and in through the edges of the paper
pad, rather than through the cellulose ester membrane capable of maintaining the appropriate flow rate (see
filter. Leakage can sometimes be eliminated by tightening
7.1 .I) to within + 5 % of the nominal value throughout
screw-threaded fittings as much as possible to compress
the sampling period (see 7.1.2). For personal sam-
and seal the edges of the paper pads, but this is not fully
pling, the pumps shall be capable of being worn by a
effective for certain types of sampler. Samplers with push-
person without impeding normal work activity. The
fit components can, in general, be used more reliably.
pumps shall give a pulsation-free flow (if necessary, a
pulsation damper shall be incorporated between the
12 Samplers manufactured in non-conducting material
sampler and the pump, as near to the pump as
have electrostatic properties which may influence represen-
possible).
tative sampling. Electrostatic influences should be reduced,
where possible, by using samplers manufactured from
NOTE 16 Flow-stabilized sampling pumps may be required
conducting material.
to maintain the flow rate within the limits specified in 6.1.3.
6.1.2 Cellulose ester membrane filters and back-
6.1.4 Portable flowmeter, capable of measuring the
up paper pads, of a diameter suitable for use in the
appropriate flow rate (see 7.1 .I) to within & 5 %, and
selected sampler (6.1.1).
calibrated against a primary standard, i.e. a flowmeter
of which the accuracy is traceable to national
The mass of arsenic of a cellulose ester membrane
standards.
filter and back-up paper pad shall be less than 0,Ol pg.
NOTES
6.1.2.1 The cellulose ester membrane filters shall
have a retentivity not less than 99 % for particles
17 The flowmeter incorporated in the sampling pump may
of median aerodynamic diameter 0,3 pm (see
be used provided that it has adequate sensitivity, that it has
IS0 7708:1995, subclause 2.2).
been calibrated against a primary standard with a loaded
sampler in line, and that it is read whilst in a vertical orien-
6.1.2.2 The back-up paper pads shall be impregnated
tation if it is of the supported float type. However, it is
with sodium carbonate in an area where arsenic important to ensure that there are no leaks in the sampling
train between the sampler and the flowmeter, since in this
contamination is known to be low, using the following
event a flowmeter in the sampling pump or elsewhere in
procedure:
line will give an erroneous flow rate.
Place the paper pads on a clean polytetrafluoro-
18 A soap bubble flowmeter may be used as a primary
ethylene (PTFE) sheet or similar, inert, flat surface
standard, provided its accuracy is traceable to national
(6.2.4). Establish the volume of sodium carbonate sol-
standards.
ution (5.2) required to just wet the entire paper pad
after the solution has been allowed to spread for a
19 If appropriate (see 7.1.3.21, the atmospheric tempera-
few minutes. Dispense this volume of sodium car-
ture and pressure at which the flowmeter was calibrated
bonate solution onto each paper pad and allow to dry should be recorded.
---------------------- Page: 6 ----------------------
IS0 11041:1996(E) @ IS0
6.15 Ancillary equipment, including flexible plastics 62.3 Piston-operated volumetric apparatus, com-
plying with the requirements of IS0 8655-l to
tubing of a diameter suitable for making a leakproof
IS0 8655-4. Automatic pipettes, as an alternative to
connection from the samplers (6.1 .I ) to the sampling
one-mark pipettes (621.3) for preparation of the
pumps (6.1.3); belts or harnesses to which the sam-
pling pumps can conveniently be fixed, unless they working standard solutions (5.12 and 5.13), calibration
are small enough to fit in workers’ pockets; flat-tipped solutions (see 8.3) and sample solutions (see 8.2.4),
forceps for loading and unloading cellulose ester and dispensers for dispensing acids and potassium
membrane filters and paper pads into samplers; and iodide solution (see 8.2 and 8.3).
filter-transport cassettes or similar, if required (see
7.4.11, to transport samples to the laboratory.
6.2.4 PTFE sheet, or other similar inert flat surface
suitable for treatment of filters and paper pads with
sodium carbonate solution.
6.1.6 Thermometer, 0 “C to 50 OC, graduated in
divisions of 1 “C or better, for measurement of at-
mospheric temperature (see 7.1.3). 6.2.5 Hotplate, thermostatically controlled, capable
of maintaining surface temperatures of approximately
150 “C (see 8.1.2), 175 “C and 200 “C (see 8.22).
6.1.7 Barometer, for measurement of atmospheric
pressure (see 7.1.3).
NOTE 22 The efficiency of thermostatting of hotplates is
sometimes deficient, and the surface temperature can also
vary considerably with position on a hotplate with a large
surface area. It may therefore be useful to characterize the
6.2 Analytical or laboratory apparatus
performance of the hotplate before use.
Ordinary laboratory apparatus, and
6.2.6 Suction filtration apparatus
6.2.1 Glassware, made of borosilicate glass 3.3
complying with the requirements of IS0 3585.
6.2.6.1 Filter funnel with support assembly, for
filtration through a 47 mm diameter filter, made of
NOTE 20 It is preferable to reserve a set of glassware for
borosilicate glass 3.3 complying with the require-
analysis of arsenic by this method. Heavily contaminated
glassware in general usage may not be satisfactorily ments of IS0 3585.
cleaned by the cleaning procedure specified in 8.1.4.
6.2.6.2 Conical flask, of capacity 1 litre, either
6.2.1.1 Beakers, of capacity 50 ml for wet-ashing of
standard or Buchner type according to the design of
cellulose ester membrane filters and back-up paper
the filter funnel with support assembly (6.2.6.1),
pads of the diameter used in the sampler (see 8.2.2),
which may incorporate the vacuum connection, and
and for preparation of the arsenic stock standard
made of borosilicate glass 3.3 complying with the re-
solution (5.11.2); of capacity 250 ml for preparation of
quirements of IS0 3585.
the sodium carbonate solution (5.2) and the potassium
iodide solution (5.9); and of capacity 1 litre for prep-
aration of sodium tetrahydroborate solution (5.14) and
6.2.6.3 Filter pump, water-operated or vacuum
sodium hydroxide solution (5. I 5).
pump, connected to the filter funnel with support
assembly (6.2.6.1) or the conical flask (6.2.6.2) with
6.2.1.2 Watch glasses, to fit the 50 ml beakers plastics tubing (6.1.5).
(6.2.1 .I).
6.2.6.4 Membrane filters, of diameter 47 mm and
6.2.1.3 One-mark pipettes, complying with the re-
pore size 0,8 pm, made of cellulose ester, PVC or
quirements of IS0 648, as an alternative to piston-
other material not degraded by sodium tetrahydro-
operated volumetric apparatus (6.2.3).
borate solution (5.14).
6.2.1.4 Measuring cylinders, of capacities between
6.2.7 Atomic absorption spectrometer, equipped
IO ml and 1 litre.
with an arsenic hollow cathode lamp or electrodeless
discharge lamp. If the absorption cell (6.2.9) is heated
6.2.1.5 One-mark volumetric flasks, of capacities
by an air/acetylene flame, the atomic absorption
between IO ml and 2 000 ml, complying with the re-
spectrometer shall be fitted with an air/acetylene
quirements of IS0 1042.
burner assembly, suitable for mounting the absorption
cell, and supplied with compressed air (5.18) and
6.2.2 Polypropylene bottles, of capacity 1 litre.
acetylene (5.19).
NOTE 21 Bottles made of alternative plastics may be
used, provided that they are suitable for the intended use 6.2.8 Hydride generation system, of one of the
(see 5.11.2, 5.12, 5.13 and 5.14).
types described in 6.2.8.1 and 6.2.8.2.
6
---------------------- Page: 7 ----------------------
IS0 11041:1996(E)
@ IS0
WARNING - Arsine (AsH3) is generated when
6.2.8.1 Continuous-flow hydride generation sys-
solutions containing arsenic are reacted with so-
tem, set up and operated according to the manu-
dium tetrahydroborate. This gas is very toxic, but
facturers’ instructions; incorporating
it will normally be produced only in very small
a) reservoirs for sodium tetrahydroborate solution
quantities. However, in order to eliminate the
and acid blank; possibility of exposure to arsine, it is essential that
the liquid waste container used be equipped with
b) an autosampler for presentation of the sample
efficient local exhaust ventilation to prevent any
solution (optional);
gases emanating from the liquid waste from
c) an inert switching valve(s), either solenoid or entering the general laboratory environment.
pneumatically actuated, to facilitate switching
6.2.9 Absorption cell, made of silica or quartz,
between sample and acid blank streams (optional);
heated either electrically or by an air/acety
...
SLOVENSKI STANDARD
SIST ISO 11041:1997
01-januar-1997
Zrak na delovnem mestu - Ugotavljanje arzenovega prahu, arzenovih spojin in
plinastega arzenovega trioksida z metodo generiranja hidrida in atomsko
absorpcijsko spektrometrijo
Workplace air -- Determination of particulate arsenic and arsenic compounds and arsenic
trioxide vapour -- Method by hydride generation and atomic absorption spectrometry
Air des lieux de travail -- Dosage de l'arsenic particulaire, des composés particulaires de
l'arsenic et des vapeurs de trioxyde d'arsenic -- Méthode par production d'hydrures et
spectrométrie d'absorption atomique
Ta slovenski standard je istoveten z: ISO 11041:1996
ICS:
13.040.30 Kakovost zraka na delovnem Workplace atmospheres
mestu
SIST ISO 11041:1997 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
---------------------- Page: 1 ----------------------
SIST ISO 11041:1997
---------------------- Page: 2 ----------------------
SIST ISO 11041:1997
---------------------- Page: 3 ----------------------
SIST ISO 11041:1997
IS0 11041:1996(E)
Foreword
IS0 (the International Organization for Standardization) is a worldwide
federation of national standards bodies (IS0 member bodies). The work of
preparing International Standards is normally carried out through IS0
technical committees. Each member body interested in a subject for
which a technical committee has been established has the right to be
represented on that committee. International organizations, governmental
and non-governmental, in liaison with ISO, also take part in the work. IS0
collaborates closely with the International Electrotechnical Commission
(IEC) on all matters of electrotechnical standardization.
Draft International Standards adopted by the technical committees are
circulated to the member bodies for voting. Publication as an International
Standard requires approval by at least 75 % of the member bodies casting
a vote.
International Standard IS0 11041 was prepared by Technical Committee
lSO/TC 146, Air quality, Subcommittee SC 2, Workplace atmospheres.
Annex A of this International Standard is for information only.
0 IS0 1996
All rights reserved. Unless otherwise specified, no part of this publication may be
reproduced or utilized in any form or by any means, electronic or mechanical, including
photocopying and microfilm, without permission in writing from the publisher.
International Organization for Standardization
Case Postale 56 l CH-1211 Geneve 20 l Switzerland
Printed in Switzerland
ii
---------------------- Page: 4 ----------------------
SIST ISO 11041:1997
IS0 11041:1996(E)
INTERNATIONAL STANDARD @ IS0
Workplace air - Determination of particulate arsenic and arsenic
compounds and arsenic trioxide vapour - Method by hydride
generation and atomic absorption spectrometry
WARNING - Arsenic and arsenic compounds are toxic and are recognized as human carcinogens (see reference
[I] in annex A). Avoid any exposure by inhalation. Personal protection (e.g. an effective respirator) must be used
in all cases where exposure to arsenic or arsenic compounds is possible.
this International Standard. At the time of publication,
1 Scope
the editions indicated were valid. All standards are
subject to revision, and parties to agreements based
This International Standard specifies a method for the
on this International Standard are encouraged to in-
determination of the mass concentration of particulate
vestigate the possibility of applying the most recent
arsenic and arsenic compounds and arsenic trioxide
editions of the standards indicated below. Members
vapour in workplace air, using either continuous-flow
of IEC and IS0 maintain registers of currently valid
hydride generation or flow-injection-analysis hydride
International Standards.
generation and atomic absorption spectrometry. The
method is not suitable for determination of arsenic in
the form of metal arsenides which decompose in the IS0 648:1977, Laboratory glassware - One-mark
presence of water or acid (see 10.1). pipettes.
The method is applicable to the determination of
IS0 1042: 1983, Laboratory glassware - One-mark
masses of approximately 100 ng to 125 pg of arsenic
volumetric flasks.
per sample, for analysis of test solutions prepared
using sample solution aliquots in the recommended
IS0 3585: 1991, Borosilicate glass 3.3 - Properties.
range (see 9.3.2). The concentration range for arsenic
in air, for which this procedure is applicable, is deter-
IS0 3696: 1987, Water for analytical labora tory use -
mined in part by the sampling procedure selected by
Specification and test methods.
the user.
IS0 6955: 1982, Analytical spectroscopic methods -
The method is applicable to personal and fixed-
Flame emission, atomic absorption and atomic
location sampling.
fluorescence - Vocabulary.
A number of transition metals may interfere with the
IS0 7708:1995, Air quality - Particle size fraction
determination of arsenic by hydride generation and
definitions for health-related sampling.
atomic absorption spectrometry (see 10.3)
IS0 8655-l :-I), Piston and/or plunger opera ted
volumetric apparatus (POVA) - Part 1: Definitions.
2 Normative references
I SO 8655-2:--l 1, Piston and/or plunger opera ted
volumetric apparatus (POVA) - Part 2: Operating
The following standards contain provisions which,
considerations.
through reference in this text, constitute provisions of
1) To be published.
1
---------------------- Page: 5 ----------------------
SIST ISO 11041:1997
0 IS0
IS0 11041:1996(E)
Piston and/or plunger opera ted charge lamp, and it is heated either electrically or by
IS0 8655-3:-l),
an oxidizing air/acetylene flame.
volumetric apparatus (POVA) - Part 3: Methods of
test.
NOTE 2 This International Standard describes the use of
two types of hydride generation system. Continuous flow
IS0 8655-4:-l), Piston and/or plunger opera ted
systems function by pumping a continuous stream of test
volumetric apparatus (POVA) - Part 4: Specifications.
solution to the mixing piece, and such systems generate a
constant atomic absorption signal. Flow injection analysis
IS0 8756: 1994, Air quality - Handling of tempera-
systems inject a discrete volume of test solution, and
ture, pressure and humidity data.
produce a transient atomic absorption signal.
EN 482: 1994, Workplace atmospheres - General
3.5 Absorbance measurements are made at
requirements for the performance of procedures for
197,2 nm or 193,7 nm, and results are obtained by the
the measurement of chemical agents. EN 482, CEN,
analytical-curve technique (see IS0 6955: 1982, sub-
Brussels, Belgium (1994).
clause 6.1 .I ), or the analyte addition technique (see
IS0 6955:1982, subclause 6.1.3).
EN 1232: --I), Workplace atmospheres - Pumps for
personal sampling of chemical agents - Require-
ments and test methods.
4 Reactions
3 Principle
4.1 In most workplace situations where exposure to
arsenic can occur (e.g. in the refining of base metals,
3.1 Particulate arsenic and arsenic compounds and
welding and other hot metal processes) a significant
arsenic trioxide vapour are collected by drawing a
proportion of the arsenic is present in the form of
measured volume of air through a cellulose ester
arsenic trioxide vapour (see reference [3] in annex A).
membrane filter and a back-up paper pad impregnated
This vapour is collected by reaction with sodium
with sodium carbonate and mounted in a sampler de-
carbonate on an impregnated back-up paper pad.
signed to collect the inhalable fraction of airborne par-
ticles.
As,O, + Na,CO, -+ ZNaAsO, + CO,
3.2 The cellulose ester membrane filter, back-up
4.2 The majority of arsenic compounds which are
paper pad and collected sample are wet-ashed using
commonly found in samples of workplace air are con-
nitric acid, sulfuric acid and hydrogen peroxide. The
verted to soluble arsenate ions (As0,3-) by the wet-
nitric acid and hydrogen peroxide are removed by
ashing procedure specified in 8.2.2. However, if there
boiling on a hotplate until dense, white fumes of sulfur
is any doubt about the effectiveness of this procedure
trioxide are evolved, and the sample solution is then
for dissolution of particulate arsenic compounds which
allowed to cool and diluted to a given volume with
could be present in the test atmosphere, investigate
water.
before proceeding with the method (see 10.2).
NOTE 1 The wet-ashing procedure specified in 8.2.2 is
based upon a NIOSH procedure (see reference [2] in annex
A) which has been modified to avoid taking the sample
4.3 Prior to hydride generation (see 4.4) arsenate
solution to dryness.
ions (AsO,s-) are reduced to arsenite ions (AsO,-) by
reaction with potassium iodide (see 8.2.4).
3.3 A test solution is prepared by transferring an
aliquot of the sample solution to a volumetric flask,
AsOds- + Zl- + 4H+ + AsO,- + I2 + 2H,O
together with appropriate volumes of dilute sulfuric
This reduction is necessary since pentavalent arsenic
acid, concentrated hydrochloric acid and potassium
gives a lower analytical response than trivalent arsenic
iodide solution, and diluting to volume with water.
because it is less rapidly converted to arsine.
3.4 The test solution is reacted with sodium tetra-
hydroborate solution in a continuous-flow hydride
generation system or flow-injection-analysis hydride
4.4 Hydride generation occurs as a result of the
generation system to liberate arsine and hydrogen.
reaction between trivalent arsenic and nascent hydro-
These gaseous products are separated from the
gen produced by the action of hydrochloric acid on
reaction liquid in a gas/liquid separator and carried by
sodium tetrahydroborate solution.
an inert purge gas into a silica or quartz absorption
cell. This absorption cell is mounted in the optical path
BH,- + H+ + 3H,O -+ H,BO, + 8H . . .
(1 >
of an atomic absorption spectrometer equipped with
an arsenic hollow cathode lamp or electrodeless dis- AsO,- + H+ + 6H + ASH, + 2H,O . . .
(2)
1) To be published.
---------------------- Page: 6 ----------------------
SIST ISO 11041:1997
IS0 11041:1996(E)
@ IS0
5.6 Nitric acid (HNO$, concentrated,
4.5 Arsenic atoms are produced from arsine by the
- I,42 g/ml, 69 % (m/m) to 71 % (d.).
action of heat in a silica or quartz absorption cell,
P
heated either by a lean air/acetylene flame or elec-
The concentration of arsenic shall be less than
trically.
0,Ol pg/ml.
WARNING - Concentrated nitric acid is corrosive
5 Reagents
and oxidizing, and nitric acid fumes are irritant.
During the analysis, use only reagents of analytical Avoid exposure by contact with the skin or eyes,
or by inhalation of fumes. Personal protective
grade, and only water as specified in 5.1.
equipment (e.g. gloves, face shield or safety spec-
5.1 Water, complying with the requirements for
tacles, etc.) must be used when working with the
IS0 3696 grade 2 water (electrical conductivity less concentrated or diluted nitric acid, and concen-
than 0,l mS/m and resistivity greater than 0,Ol ML&m
trated nitric acid must be used in a fume hood.
at 25 “C).
5.7 Sulfuric acid (HzSOa), concentrated,
5.2 Sodium carbonate, 1 mol/l solution in 5 %
w I,84 g/ml, about 98 % (m/m).
P
glycerol solution.
The concentration of arsenic shall be less than
to a
Weigh IO,6 g of sodium carbonate (Na2C03) it 0,05 pg/ml.
and
250 ml beaker (6.2.1 .I). Add 5 ml of glycerol
WARNING - Concentrated sulfuric acid is corros-
50 ml of water (5.1) and swirl to dissolve. Quantita-
ive and causes burns. Avoid exposure by contact
tively transfer the solution to a 100 ml one-mark
with the skin or eyes. Personal protective equip-
volumetric flask (6.2.1.5) dilute to the mark with
ment (e.g. gloves, face shield or safety spectacles,
water, stopper and mix thoroughly.
etc.) must be used when working with the con-
centrated or diluted sulfuric acid. Fumes produced
5.3 Hydrochloric acid (HCI), concentrated
by heating concentrated sulfuric acid are irritant,
- 1 ,I8 g/ml, 35 % (m/m) to 36 % (m/m).
P
and this operation must therefore be carried out in
a fume hood. Caution must be exercised if adding
The concentration of arsenic shall be less than
water to sulfuric acid, since this reacts violently
0,Ol pg/ml.
with water (acid/water mixtures must be prepared
WARNING - Concentrated hydrochloric acid is
by adding acid to water).
corrosive, and hydrochloric acid vapour is irritant.
Avoid exposure by contact with the skin or eyes,
5.8 Hydrogen peroxide (HzO$, approximately
or by inhalation of fumes. Personal protective
30 % (m/m) solution.
equipment (e.g. gloves, face shield or safety spec-
tacles, etc.) must be used when working with the The concentration of arsenic shall be less than
concentrated or diluted hydrochloric acid, and 0,Ol pg/rnl.
concentrated hydrochloric acid must be used in a
WARNING - Hydrogen peroxide is corrosive and
fume hood. The vapour pressure of hydrochloric is
oxidizing. Avoid exposure be contact with the skin
high, therefore beware of pressure build-up in
or eyes. Personal protective equipment (e.g.
stoppered flasks when preparing acid/water
gloves, face shield or safety spectacles, etc.) must
mixtures.
be used when working with protective equipment
5.4 Hydrochloric acid, diluted 1 + 1. hydrogen peroxide.
Pour approximately 900 ml of water (5.1) into a 5.9 Potassium iodide, 100 g/l solution.
2 000 ml one-mark volumetric flask (6.2.1.5). Carefully
Weigh IO,0 g of potassium iodide (KI) into a 250 ml
add 1 000 ml of concentrated hydrochloric acid (5.3) to
beaker (6.2.1 .I ). Add 50 ml of water (5.1) and swirl to
the flask and swirl to mix. Allow to cool, dilute to the
dissolve. Quantitatively transfer the solution to a
mark with water, stopper and mix thoroughly.
100 ml one-mark volumetric flask (6.2.1.5) dilute to
NOTE 3 This is used as the solvent blank, as defined in the mark with water, stopper and mix thoroughly.
IS0 6955:1982, subclause 5.4.2, but in this International
Standard the solvent blank is referred to as the acid blank.
Prepare a fresh solution each month.
5.5 Hydrochloric acid, diluted 1 + 4.
5.18 Sulfuric acid, diluted 1 + 9.
Pour approximately 700 ml of water (5.1) into a Carefully add 25 ml of concentrated sulfuric acid (5.7)
1 000 ml one-mark volumetric flask (6.2.1.5). Carefully to 200 ml of water (5.1) in a 1 litre beaker. Swirl to
add 200 ml of concentrated hydrochloric acid (5.3) to
mix, allow to cool and quantitatively transfer to a
the flask and swirl to mix. Allow to cool, dilute to the
250 ml one-mark volumetric flask (6.2.1.5). Dilute to
mark with water, stopper and mix thoroughly.
the mark with water, stopper and mix thoroughly.
3
---------------------- Page: 7 ----------------------
SIST ISO 11041:1997
IS0 11041:1996(E) @ IS0
5.11 Arsenic stock standard solution, correspond- ide (NaOH) pellets into a 1 litre beaker (6.2.1 .I). Add
ing to 1 000 mg of As per litre. 200 ml of water (5.1) and swirl to mix. Quantitatively
transfer the solution to a 1 000 ml one-mark volu-
511.1 Use a commercially available arsenic standard
metric flask (6.2.1.5) filtering through a membrane
solution at a concentration of 1 000 mg/l. Observe the
filter using a suction filtration apparatus (6.2.6). Dilute
manufacturer’s expiry date or recommended shelf-life.
to the mark with water (5.1) stopper and mix
thoroughly.
Alternatively, prepare an arsenic standard solution
according to the procedure specified in 5.11.2.
Prepare a fresh solution daily.
511.2 Accurately weigh 1,320 g + 0,001 g of arsenic NOTES
trioxide (As203) into a 50 ml beaker (6.2.1.1), add
4 Filtration of the solution is necessary to remove
10 ml of concentrated hydrochloric acid - (5.3), cover
undissolved particulate material which might otherwise
with a watch glass (6.2.1.2) and heat to approximately
cause clogging of the tubing or mixing piece of the hydride
150 “C on the hotplate (6.2.5) in a fume hood until dis-
generation system (6.2.8). The addition of alkali minimizes
solution is complete. Remove the beaker from the
hydrolysis of the sodium tetrahydroborate solution.
hotplate, allow to cool, quantitatively transfer the sol-
ution to a 1 000 ml one-mark volumetric flask (6.2.1.5)
5 A few drops of anti-foaming agent may be added to the
dilute to the mark with hydrochloric acid diluted 1 + 1
solution to reduce foaming in the gas/liquid separator of the
(5.4), stopper and mix thoroughly.
hydride generation system (6.2.8) which may result in a
noisy baseline signal.
This solution may be stored in a polypropylene bottle
6 The solution should be stored in a polypropylene bottle
(6.2.2) for up to one year.
(6.2.2) if it is not transferred to the reductant reservoir of
the continuous hydride generation system (6.2.8) immedi-
WARNING - Arsenic trioxide is toxic and is
ately after preparation (see 8.4.2.2). The top of the bottle
recognized as a human carcinogen (see reference
should not be fully tightened or pressure will build up due
[I] in annex A). See the general warning about
to the slow release of hydrogen.
arsenic or arsenic compounds, just after the title
of this International Standard.
5.15 Sodium hydroxide, 5 g/l solution.
5.12 Arsenic working standard solution A, corre-
Weigh 5,0 g of sodium hydroxide (NaOH) pellets into a
sponding to 10 mg of As per litre.
1 litre beaker (6.2.1 .I). Add 250 ml of water (5.1) and
swirl to dissolve. Quantitatively transfer the solution to
Using a pipette (6.2.1.3), accurately add I,00 ml of
a 1 000 ml volumetric flask (6.2.1.5) dilute to the mark
stock arsenic solution (5.11) to a 100 ml one-mark
with water, stopper and mix thoroughly.
volumetric flask (6.2.1.5) dilute to the mark with
hydrochloric acid diluted 1 + 1 (5.4) stopper and mix
5.16 Laboratory
detergent solution, suitable for
thoroughly.
cleaning samplers
and laboratory apparatus, diluted
with water (5.1)
according to the manufacturer’s
This solution may be stored in a polypropylene bottle
instructions.
(6.2.2) for up to one month.
5.17 Inert purge gas, for example argon or nitro-
5.13 Arsenic working standard solution B,
gen, supplied in a cylinder or as a cryogenic fluid.
corresponding to 1 mg of As per litre.
Using a pipette (6.2.1.3), accurately add 10 ml of 5.18 Air, compressed and filtered.
working arsenic solution A (5.12) to a 100 ml one-mark
NOTE 7 This gas is not required if the silica or quartz
volumetric flask (6.2.1.5), dilute to the mark with
absorption cell (6.2.9) used is electrically heated.
hydrochloric acid diluted 1 + 1 (5.4) stopper and mix
thoroughly.
5.19 Acetylene, in a cylinder.
This solution may be stored in a polypropylene bottle
NOTE 8 This gas is not required if the silica or quartz
(6.2.2) for up to one month.
absorption cell (6.2.9) used is electrically heated.
5.14 Sodium tetrahydroborate, solution corre-
sponding to between 2 g and 20 g of sodium tetra-
hydroborate per litre in 0,l mol/l sodium hydroxide
6 Apparatus
solution.
Prepare a sodium tetrahydroborate solution at the 6.1 Sampling equipment
concentration recommended by the manufacturer of
6.1.1 Samplers, for collection of the inhalable frac-
the hydride generation system (6.2.8). Weigh be-
tion of airborne particles (see 7.1 .I) as defined in
tween 2 g and 20 g of sodium tetrahydroborate
IS0 7708, suitable for use with the cellulose ester
(NaBHd) pellets or powder and 4 g of sodium hydrox-
4
---------------------- Page: 8 ----------------------
SIST ISO 11041:1997
@ IS0 IS0 11041:1996(E)
membrane filters and back-up paper pads (6.1.2) and for several hours at room temperature. Store the
with the sampling pumps (6.1.3) used. paper pads impregnated with sodium carbonate in an
compatible
airtight container and use within one week of prep-
NOTES aration.
9 A number of different terms are used to describe sam-
NOTES
plers designed for collection of the inhalable fraction of air-
borne particles, for example, sampling heads, filter holders,
13 The volume of sodium carbonate solution required to
filter cassettes and air monitoring cassettes.
impregnate the back-up paper pads is typically 175 ~1 for a
25 mm diameter paper pad or 400 ~1 for a 37 mm diameter
10 In general, the collection characteristics of inhalable
paper pad.
samplers are such that particulate material collected on the
filter is the inhalable fraction of airborne particles, and any
14 The drying time for paper pads impregnated with
deposited on the internal surfaces of the sampler is not of
sodium carbonate may be reduced by placing them in an
interest. However, some samplers are designed such that
oven at 40 “C for 45 min.
airborne particles which pass through the entry orifice(s)
constitute the inhalable fraction; in which case any particu-
15 Glass-fibre or quartz-fibre filters impregnated with so-
late material deposited on the internal surfaces of the sam-
dium carbonate have also been shown to be efficient for
pler is part of the sample. Certain samplers of this type
collecting arsenic trioxide vapour (see reference [4] in annex
incorporate an internal filter cassette or cartridge which
A) and may be used as an alternative to cellulose ester
may be removed from the sampler to enable this material
membrane filters and back-up paper pads impregnated with
to be easily recovered.
sodium carbonate. Neither glass-fibre nor quartz-fibre filters
are dissolved by the wet-ashing procedure specified in
11 Samplers which are assembled by means of screw-
8.2.2, but this may be modified to permit their use (see
threaded fittings may be unsuitable for use with a cellulose
note 33).
ester membrane filter and a back-up paper pad. The high
restriction of a cellulose ester membrane filter, compared
6.1.3 Sampling pumps, complying with the require-
with that of a paper pad, means that there is a tendency for
ments of EN 1232, with an adjustable flow rate, incor-
air to take the path of least resistance and to be drawn
porating a flowmeter or a flow-fault indicator, and
along screw threads and in through the edges of the paper
pad, rather than through the cellulose ester membrane capable of maintaining the appropriate flow rate (see
filter. Leakage can sometimes be eliminated by tightening
7.1 .I) to within + 5 % of the nominal value throughout
screw-threaded fittings as much as possible to compress
the sampling period (see 7.1.2). For personal sam-
and seal the edges of the paper pads, but this is not fully
pling, the pumps shall be capable of being worn by a
effective for certain types of sampler. Samplers with push-
person without impeding normal work activity. The
fit components can, in general, be used more reliably.
pumps shall give a pulsation-free flow (if necessary, a
pulsation damper shall be incorporated between the
12 Samplers manufactured in non-conducting material
sampler and the pump, as near to the pump as
have electrostatic properties which may influence represen-
possible).
tative sampling. Electrostatic influences should be reduced,
where possible, by using samplers manufactured from
NOTE 16 Flow-stabilized sampling pumps may be required
conducting material.
to maintain the flow rate within the limits specified in 6.1.3.
6.1.2 Cellulose ester membrane filters and back-
6.1.4 Portable flowmeter, capable of measuring the
up paper pads, of a diameter suitable for use in the
appropriate flow rate (see 7.1 .I) to within & 5 %, and
selected sampler (6.1.1).
calibrated against a primary standard, i.e. a flowmeter
of which the accuracy is traceable to national
The mass of arsenic of a cellulose ester membrane
standards.
filter and back-up paper pad shall be less than 0,Ol pg.
NOTES
6.1.2.1 The cellulose ester membrane filters shall
have a retentivity not less than 99 % for particles
17 The flowmeter incorporated in the sampling pump may
of median aerodynamic diameter 0,3 pm (see
be used provided that it has adequate sensitivity, that it has
IS0 7708:1995, subclause 2.2).
been calibrated against a primary standard with a loaded
sampler in line, and that it is read whilst in a vertical orien-
6.1.2.2 The back-up paper pads shall be impregnated
tation if it is of the supported float type. However, it is
with sodium carbonate in an area where arsenic important to ensure that there are no leaks in the sampling
train between the sampler and the flowmeter, since in this
contamination is known to be low, using the following
event a flowmeter in the sampling pump or elsewhere in
procedure:
line will give an erroneous flow rate.
Place the paper pads on a clean polytetrafluoro-
18 A soap bubble flowmeter may be used as a primary
ethylene (PTFE) sheet or similar, inert, flat surface
standard, provided its accuracy is traceable to national
(6.2.4). Establish the volume of sodium carbonate sol-
standards.
ution (5.2) required to just wet the entire paper pad
after the solution has been allowed to spread for a
19 If appropriate (see 7.1.3.21, the atmospheric tempera-
few minutes. Dispense this volume of sodium car-
ture and pressure at which the flowmeter was calibrated
bonate solution onto each paper pad and allow to dry should be recorded.
---------------------- Page: 9 ----------------------
SIST ISO 11041:1997
IS0 11041:1996(E) @ IS0
6.15 Ancillary equipment, including flexible plastics 62.3 Piston-operated volumetric apparatus, com-
plying with the requirements of IS0 8655-l to
tubing of a diameter suitable for making a leakproof
IS0 8655-4. Automatic pipettes, as an alternative to
connection from the samplers (6.1 .I ) to the sampling
one-mark pipettes (621.3) for preparation of the
pumps (6.1.3); belts or harnesses to which the sam-
pling pumps can conveniently be fixed, unless they working standard solutions (5.12 and 5.13), calibration
are small enough to fit in workers’ pockets; flat-tipped solutions (see 8.3) and sample solutions (see 8.2.4),
forceps for loading and unloading cellulose ester and dispensers for dispensing acids and potassium
membrane filters and paper pads into samplers; and iodide solution (see 8.2 and 8.3).
filter-transport cassettes or similar, if required (see
7.4.11, to transport samples to the laboratory.
6.2.4 PTFE sheet, or other similar inert flat surface
suitable for treatment of filters and paper pads with
sodium carbonate solution.
6.1.6 Thermometer, 0 “C to 50 OC, graduated in
divisions of 1 “C or better, for measurement of at-
mospheric temperature (see 7.1.3). 6.2.5 Hotplate, thermostatically controlled, capable
of maintaining surface temperatures of approximately
150 “C (see 8.1.2), 175 “C and 200 “C (see 8.22).
6.1.7 Barometer, for measurement of atmospheric
pressure (see 7.1.3).
NOTE 22 The efficiency of thermostatting of hotplates is
sometimes deficient, and the surface temperature can also
vary considerably with position on a hotplate with a large
surface area. It may therefore be useful to characterize the
6.2 Analytical or laboratory apparatus
performance of the hotplate before use.
Ordinary laboratory apparatus, and
6.2.6 Suction filtration apparatus
6.2.1 Glassware, made of borosilicate glass 3.3
complying with the requirements of IS0 3585.
6.2.6.1 Filter funnel with support assembly, for
filtration through a 47 mm diameter filter, made of
NOTE 20 It is preferable to reserve a set of glassware for
borosilicate glass 3.3 complying with the require-
analysis of arsenic by this method. Heavily contaminated
glassware in general usage may not be satisfactorily ments of IS0 3585.
cleaned by the cleaning procedure specified in 8.1.4.
6.2.6.2 Conical flask, of capacity 1 litre, either
6.2.1.1 Beakers, of capacity 50 ml for wet-ashing of
standard or Buchner type according to the design of
cellulose ester membrane filters and back-up paper
the filter funnel with support assembly (6.2.6.1),
pads of the diameter used in the sampler (see 8.2.2),
which may incorporate the vacuum connection, and
and for preparation of the arsenic stock standard
made of borosilicate glass 3.3 complying with the re-
solution (5.11.2); of capacity 250 ml for preparation of
quirements of IS0 3585.
the sodium carbonate solution (5.2) and the potassium
iodide solution (5.9); and of capacity 1 litre for prep-
aration of sodium tetrahydroborate solution (5.14) and
6.2.6.3 Filter pump, water-operated or vacuum
sodium hydroxide solution (5. I 5).
pump, connected to the filter funnel with support
assembly (6.2.6.1) or the conical flask (6.2.6.2) with
6.2.1.2 Watch glasses, to fit the 50 ml beakers plastics tubing (6.1.5).
(6.2.1 .I).
6.2.6.4 Membrane filters, of diameter 47 mm and
6.2.1.3 One-mark pipettes, complying with the re-
pore size 0,8 pm, made of cellulose ester, PVC or
quirements of IS0 648, as an alternative to piston-
other material not degraded by sodium tetrahydro-
operated volumetric apparatus (6.2.3).
borate solution (5.14).
6.2.1.4 Measuring cylinders, of capacities between
6.2.7 Atomic absorption spectrometer, equipped
IO ml and 1 litre.
with an arsenic hollow cathode lamp or electrodeless
discharge lamp. If the absorption cell (6.2.9) is heated
6.2.1.5 One-mark volumetric flasks, of capacities
by an air/acetylene flame, the atomic absorption
between IO ml and 2 000 ml, complying with the re-
spectrometer shall be fitted with an air/acetylene
quirements of IS0 1042.
burner assembly, suitable for mounting the absorption
cell, and supplied with compressed air (5.18) and
6.2.2 Polypropylene bottles, of capacity 1 litre.
acetylene (5.19).
NOTE 21 Bottles made of alternative plastics may be
used, provided that they are suitable f
...
NORME
ISO
INTERNATIONALE
11041
Première édition
1996-04-15
Air des lieux de travail - Dosage de
l’arsenic particulaire, des composés
particulaires de l’arsenic et des vapeurs de
trioxyde d’arsenic - Méthode par
production d’hydrures et spectrométrie
d’absorption atomique
Workplace air - De termina tion of particula te arsenic and arsenic
compounds and arsenic trioxide vapour - Method b y h ydride generation
and atomic absorption spectrometry
Numéro de référence
ISO II 041 :1996(F)
---------------------- Page: 1 ----------------------
ISO 11041:1996(F)
Avant-propos
L’ISO (Organisation internationale de normalisation) est une fédération
mondiale d’organismes nationaux de normalisation (comités membres de
I’ISO). L’élaboration des Normes internationales est en général confiée aux
comités techniques de I’ISO. Chaque comité membre intéressé par une
étude a le droit de faire partie du comité technique créé à cet effet. Les
organisations internationales, gouvernementales et non gouvernemen-
tales, en liaison avec I’ISO participent également aux travaux. L’ISO colla-
bore étroitement avec la Commission électrotechnique internationale (CEI)
en ce qui concerne la normalisation électrotechnique.
Les projets de Normes internationales adoptés par les comites techniques
sont soumis aux comités membres pour vote. Leur publication comme
Normes internationales requiert l’approbation de 75 % au moins des co-
mités membres votants.
La Norme internationale ISO 11041 a été élaborée par le comité technique
lSO/K 146, Qualité de l’air, sous-comité SC 2, Atmosphères des lieux de
travail.
L’annexe A de la présente Norme internationale est donnée uniquement à
titre d’information.
0 60 1996
Droits de reproduction réservés. Sauf prescription différente, aucune partie de cette publi-
cation ne peut être reproduite ni utilisée sous quelque forme que ce soit et par aucun pro-
cédé, électronique ou mécanique, y compris la photocopie et les microfilms, sans l’accord
écrit de l’éditeur.
Organisation internationale de normalisation
Case postale 56 l CH-l 211 Genève 20 l Suisse
Imprimé en Suisse
ii
---------------------- Page: 2 ----------------------
NORME INTERNATIONALE @ ISO ISO 11041:1996(F)
Air des lieux de travail - Dosage de l’arsenic particulaire, des
composés particulaires de l’arsenic et des vapeurs de trioxyde
d’arsenic - Méthode par production d’hydrures et spectrométrie
d’absorption atomique
AVERTISSEMENT - L’arsenic et les composés de l’arsenic sont toxiques et cancérigènes pour l’homme (voir
référence bibliographique [1] citée dans l’annexe A). Éviter toute exposition par inhalation. Il convient d’utiliser
une protection individuelle (par exemple un masque protecteur) dans tous les cas où il existe un risque
d’exposition à l’arsenic ou à des composés de l’arsenic.
1 Domaine d’application 2 Rbférences normatives
La présente Norme internationale prescrit une métho- Les normes suivantes contiennent des dispositions
de pour la détermination de la concentration en masse qui, par suite de la référence qui en est faite, consti-
de l’arsenic particulaire, des composés particulaires de tuent des dispositions valables pour la présente
l’arsenic et des vapeurs de trioxyde d’arsenic dans Norme internationale. Au moment de la publication,
l’air des lieux de travail, soit par production d’hydrures les éditions indiquées étaient en vigueur. Toute norme
en flux continu, soit par production d’hydrures avec est sujette à révision et les parties prenantes des
injection de flux pour analyse, et spectrométrie d’ab- accords fondés sur la présente Norme internationale
sorption atomique. La méthode ne convient pas pour sont invitées à rechercher la possibilité d’appliquer les
le dosage de l’arsenic sous forme d’arséniures métal- éditions les plus récentes des normes indiquées ci-
liques qui se décomposent en présence d’eau ou
après. Les membres de la CEI et de I’ISO possèdent
d’acide (voir 10.1). le registre des Normes internationales en vigueur à un
moment donné.
La méthode est applicable à la détermination de
masses d’environ 100 ng à 125 pg d’arsenic par
ISO 648:1977, Verrerie de laboratoire - Pipettes à un
échantillon, pour l’analyse de solutions d’essai prépa-
trait.
rées à l’aide de parties aliquotes de solution échan-
tillon dans la gamme recommandée (voir 9.3.2). La
ISO 1042:1983, Verrerie de laboratoire - Fioles jau-
gamme de concentrations d’arsenic dans l’air pour
gées à un trait.
mode opératoire est applicable est déter-
laquelle ce
partie par le mode opératoire d’échan-
minée en
ISO 3585:1991, Verre borosilicaté 3.3 - Propriétés.
t loisi par l’utilisateur.
tillonnage c
ISO 3696:1987, Eau pour laboratoire à usage analy-
La méthode est applicable à l’échantillonnage indivi-
tique - Spécifica tion et méthodes d ‘essai.
duel et à l’échantillonnage à point fixe.
ISO 6955: 1982, Méthodes d’analyse par spectro-
Certains métaux de transition peuvent interférer dans
Émission de flamme, absorption atomique
scopie -
le dosage de l’arsenic par production d’hydrures/
et fluorescence atomique - Vocabulaire.
spectrométrie d’absorption atomique (voir 10.3).
---------------------- Page: 3 ----------------------
63 ISO
ISO 11041:1996(F)
solution d’iodure de potassium, et en complétant au
ISO 7708: 1995, Qualité de l’air - Définitions des frac-
volume avec de l’eau.
tions de tailles des particules pour l’échantillonnage lié
aux problèmes de santé.
3.4 On fait réagir la solution d’essai avec une solu-
tion de tétrahydroborate de sodium, dans un système
ISO 8655-l : -1 1, /ns trumen ts volumétriques à pis ton
de production d’hydrures soit en flux continu soit par
et/ou à plongeur (IVAP) - Partie 1: Définitions.
injection, pour libérer I’arsine et l’hydrogène. Ces
produits gazeux sont séparés de la phase de réaction
-Il, /ns trumen ts volumétriques à pis ton
ISO 8655-2:
dans un séparateur gaz/liquide et amenés à l’aide d’un
et/ou à plongeur (IVAP) - Partie 2: Considérations sur
gaz de purge inerte dans une cuve d’absorption en
I ‘utilisation.
silice ou en quartz. Cette cuve d’absorption est mon-
tée dans le trajet optique d’un spectromètre d’absorp-
ISO 8655-3: --.l 1, /ns trumen ts volumétriques à pis ton
tion atomique équipé d’une lampe à arsenic à cathode
et/ou à plongeur (IVAP) - Partie 3: Méthodes d’essai.
creuse ou d’une lampe à décharge sans électrode, et
chauffée électriquement ou par une flamme oxydante
ISO 8655-4: -l), /ns trumen ts volumétriques à pis ton
air/acétylène.
- Partie 4: Spécifications.
evou à plongeur (IVAP)
NOTE 2 La présente Norme internationale décrit I’utilisa-
ISO 8756:1994, Qualité de l’air - Traitement des
tion de deux types de systèmes de production d’hydrures.
données de température, de pression et d’humidité.
Les systèmes à flux continu fonctionnent par pompage
d’un flux continu de solution d’essai vers le mélangeur; ces
EN 482:1994, Atmosphères des lieux de travail -
systèmes donnent naissance à un signal d’absorption
Exigences générales concernant les performances
atomique constant. Les systèmes d’analyse par injection
des procédures de mesurages des agents chimiques.
injectent un volume donné de solution d’essai et produisent
un signal d’absorption atomique transitoire.
EN 1232: -11, Atmosphères des lieux de travail -
Pompes pour échantillonnage personnel des agents 3.5 Les mesurages d’absorbance sont réalisés
chimiques - Spécifications et méthodes d ‘essai. à 197,2 nm ou 193,7 nm, et les résultats sont
obtenus par la méthode directe de dosage (voir
ISO 6955:1982, paragraphe 6.1 .l) ou la méthode de
3 Principe
dosage par ajouts dosés (voir ISO 6955:1982, para-
graphe 6.1.3).
3.1 On recueille l’arsenic particulaire, les composés
particulaires de l’arsenic et les vapeurs de trioxyde
d’arsenic en faisant passer un volume d’air mesuré à
4 Réactions
travers une membrane filtrante en ester de cellulose
et un tampon en cellulose placé en aval et imprégné
4.1 Dans la plupart des lieux de travail où existe un
de carbonate de sodium, installés dans un échantillon-
risque d’exposition à l’arsenic (par exemple dans
neur destiné à recueillir la fraction inhalable des parti-
l’affinage de métaux, le soudage et autres procédés à
cules d’aérosol.
chaud), une proportion significative de l’arsenic est
présente sous forme de vapeur de trioxyde d’arsenic
3.2 La membrane filtrante en ester de cellulose, le
(voir référence bibliographique [3] citée dans l’annexe
tampon en cellulose placé en aval et l’échantillon re-
A). Cette vapeur est recueillie par réaction avec le
cueilli sont digérés en phase humide à l’aide d’acide
carbonate de sodium sur un tampon en cellulose
nitrique, d’acide sulfurique et de peroxyde d’hydro-
imprégné, placé en aval.
gène. L’acide nitrique et le peroxyde d’hydrogène sont
éliminés par ébullition sur une plaque chauffante jus-
As,O, + Na,CO, + 2NaAs0, + CO,
qu’à l’apparition de denses fumées blanches de
trioxyde de soufre; on laisse ensuite refroidir la solu-
4.2 La plupart des composés de l’arsenic que l’on
tion que l’on complète à un volume donné avec de
trouve couramment dans les échantillons d’air de lieux
l’eau.
de travail sont convertis en ions arséniates solubles
(As0,3-) par minéralisation en phase humide, confor-
NOTE 1 Le mode opératoire de dissolution d’échantillon
mément au mode opératoire prescrit en 8.2.2. En cas
prescrit en 8.22 est fondé sur un mode opératoire du
de doute sur l’efficacité de ce mode opératoire pour
NIOSH (voir référence bibliographique [Z] citée dans I’an-
dissoudre les composés particulaires de l’arsenic sus-
nexe A), qui a été modifié afin d’éviter d’amener la solution
ceptibles d’être présents dans l’atmosphère d’essai,
à sec.
en vérifier l’efficacité avant de l’appliquer (voir 10.2).
33 . On prépare une solution d’essai en transférant
4.3 Avant la production d’hydrures (voir 4.4) les ions
une partie aliquote de la solution échantillon dans une
arséniates (As0,3-) sont réduits en ions arsénites
fiole jaugée, avec des volumes appropriés d’acide
(AsO,-) par l’iodure de potassium (voir 8.2.4).
sulfurique dilué, d’acide chlorhydrique concentré et de
AS~$- + Zl- + 4H + + AsO,- + l2 + 2H,O
1) À publier.
2
---------------------- Page: 4 ----------------------
0 ISO
ISO 11041:1996(F)
5.4 Acide chlorhydrique, dilué 1 + 1.
Cette réduction est nécessaire parce que l’arsenic
pentavalent donne une réponse plus faible que I’ar-
Verser environ 900 ml d’eau (5.1) dans une fiole
senic trivalent, car il est moins rapidement converti en
jaugée à un trait de 2 000 ml (6.2.1.5). Ajouter soi-
arsine.
gneusement 1 000 ml d’acide chlorhydrique concentré
(5.3) et mélanger.
Laisser refroidir, compléter au
4.4 La production d’hydrures résulte de la réaction
volume avec de l’eau, boucher et bien mélanger.
entre l’arsenic trivalent et l’hydrogène naissant produit
par l’action de l’acide chlorhydrique sur la solution de
NOTE 3 Cette solution est utilisée comme solution de
tétrahydroborate de sodium.
tarage, telle qu’elle est définie dans ISO 6955:1982, para-
graphe 5.42, mais, dans la présente Norme internationale,
BH,- + H+ + 3H,O -+ H,BO, + 8H . . .
(1 1
la solution de tarage est appelée blanc d’acide.
AsO,- + H+ + 6H + AsH, + 2H,O . . .
(2
5.5 Acide chlorhydrique, dilué 1 + 4.
4.5 Les atomes d’arsenic sont produits à partir de
Verser environ 700 ml d’eau (5.1) dans une fiole jau-
I’arsine par l’action de la chaleur dans une cuve d’ab-
gée à un trait de 1 000 ml (6.2.1.5). Ajouter avec pré-
sorption en silice ou en quartz chauffée électrique-
caution 200 ml d’acide chlorhydrique concentré (5.3)
ment ou par une flamme pauvre air/acétylène.
et mélanger. Laisser refroidir, compléter au volume
avec de l’eau, boucher et bien mélanger.
5.6 Acide nitrique (HNO,), concentré, p = 1,42 g/mI,
69 %(mhn)à71 % (ndm).
5 Réactifs
La concentration d’arsenic doit être inférieure à
Au cours de l’analyse, utiliser uniquement des réactifs
0,Ol pg/mI.
de qualité analytique et de l’eau conforme aux pres-
criptions de 5.1.
AVERTISSEMENT - L’acide nitrique concentré est
corrosif et oxydant, et les vapeurs d’acide nitrique
sont irritantes. Eviter le contact avec la peau ou
5.1 Eau de qualité 2, conforme aux prescriptions de
les yeux, ou l’inhalation des vapeurs. II convient
I’ISO 3696 (conductivité électrique inférieure à
d’utiliser une protection individuelle (gants, écran
0,l mS/m et résistivité supérieure à 0,Ol MQm à
facial ou lunettes de sécurité, etc.) pour manipuler
25 OC).
l’acide nitrique concentré ou dilué, et d’utiliser une
hotte d’aspiration pour l’acide nitrique concentré.
5.2 Carbonate de sodium, solution à 1 mol par litre
d’une solution de glycérol à 5 % (WV).
5.7 Acide sulfurique (H,SO,), concentré,
p = 1,84 g/mI, environ 98 % (m/m).
Peser 10,6 g de carbonate de sodium (Na2C03) dans
un bécher de 250 ml (6.2.1 .l). Ajouter 5 ml de glycérol La concentration d’arsenic doit être inférieure à
et 50 ml d’eau (5.1), et mélanger jusqu’à dissolution. 0,05 pg/mI.
Transférer quantitativement la solution dans une fiole
AVERTISSEMENT - L’acide sulfurique concentré
jaugée à un trait de 100 ml (6.2.1.5), compléter au
est corrosif et provoque des brûlures. Éviter le
volume avec de l’eau, boucher et bien mélanger.
contact avec la peau ou les yeux. II convient
d’utiliser une protection individuelle (gants, écran
5.3 Acide chlorhydrique (HCI), concentré,
facial ou lunettes de sécurité, etc.) pour manipuler
p = 1,18 g/mI, 35 % (m/m) à 36 % (&Y).
l’acide sulfurique concentré ou dilué. Les vapeurs
dégagées lorsqu’on chauffe de l’acide sulfurique
La concentration d’arsenic doit être inférieure à
concentré sont irritantes; il convient donc d’effec-
0,Ol pg/mI.
tuer cette opération sous une hotte d’aspiration. II
y a lieu de prendre des précautions si l’on ajoute
AVERTISSEMENT - L’acide chlorhydrique con-
de l’eau à l’acide sulfurique, car ce dernier réagit
centré est corrosif, et les vapeurs d’acide chlor-
violemment avec l’eau (il faut préparer des
hydrique sont irritantes. Eviter le contact avec la
mélanges acide/eau en ajoutant de l’acide à l’eau).
peau ou les yeux, ou l’inhalation des vapeurs. II
convient d’utiliser une protection individuelle
5.8 Peroxyde d’hydrogène (H*O,), solution à envi-
(gants, écran facial ou lunettes de sécurité, etc.)
ron 30 % (m/m).
pour manipuler l’acide chlorhydrique concentré ou
dilué, et d’utiliser une hotte d’aspiration pour
La concentration d’arsenic doit être inférieure à
l’acide chlorhydrique concentré. La pression de
0,Ol pg/ml.
vapeur de l’acide chlorhydrique est élevée; atten-
tion à la montée en pression dans les fioles bou- AVERTISSEMENT - Le peroxyde d’hydrogène est
chées lors de la préparation de mélanges corrosif et oxydant. Éviter le contact avec la peau
acide/eau. ou les yeux. II convient d’utiliser une protection
3
---------------------- Page: 5 ----------------------
0 ISO
ISO 11041:1996(F)
Introduire avec précision, à l’aide d’une pipette (6.2.1.3),
individuelle (gants, écran facial ou lunettes de
1,OO ml de la solution mère étalon d’arsenic (5.11) dans
sécurité, etc.) pour manipuler le peroxyde d’hydro-
gène. une fiole jaugée à un trait de 100 ml (6.2.1.5) compléter
au volume avec de l’acide chlorhydrique dilué 1 + 1 (5.4),
.
boucher et bien mélanger.
5.9 Iodure de potassium, solution à 100 g/l.
Cette solution peut être conservée dans un flacon en
Peser 10,O g d’iodure de potassium (KI) dans un bécher
polypropylène (6.2.2) pendant une durée maximale d’un
de 250 ml (6.2.1 .l). Ajouter 50 ml d’eau (5.1) et mélanger
mois.
jusqu’à dissolution. Transférer quantitativement la solu-
tion dans une fiole jaugée à un trait de 100 ml (6.2.1.5)
compléter au volume avec de l’eau, boucher et bien
5.13 Solution fille étalon d’arsenic 9, correspon-
mélanger. dant à 1 mg de As par litre.
Préparer une nouvelle solution tous les mois.
Introduire avec précision, à l’aide d’une pipette (6.2.1.3)
10,O ml de la solution fille étalon d’arsenic A (5.12) dans
une fiole jaugée à un trait de 100 ml (6.2.1.5) compléter
5.10 Acide sulfurique, dilué 1 + 9.
au volume avec de l’acide chlorhydrique dilué 1 + 1 (5.4)
boucher et bien mélanger.
Ajouter avec précaution 25 ml d’acide sulfurique concen-
tré (5.7) à 200 ml d’eau (5.1) dans un bécher de 1 litre.
Cette solution peut être conservée dans un flacon en
Mélanger, laisser refroidir et transférer quantitativement
polypropylène (6.2.2) pendant une durée maximale d’un
dans une fiole jaugée à un trait de 250 ml (6.2.1.5).
mois.
Compléter au volume avec de l’eau, boucher et bien
mélanger.
5.14 Tétrahydroborate de sodium, solution cor-
respondant à une quantité comprise entre 2 g et 20 g
5.11 Solution mère étalon d’arsenic, correspon-
de tétrahydroborate de sodium par litre d’une solution
dant à 1 000 mg de As par litre.
d’hydroxyde de sodium à 0,l mol/l.
5.11.1 Utiliser une solution étalon d’arsenic du com-
Préparer une solution de tétrahydroborate de sodium à la
merce, à une concentration de 1 000 mg/l. Respecter la
concentration recommandée par le fabricant du système
date limite d’utilisation ou la durée de conservation
de production d’hydrures (6.2.8). Peser une quantité
recommandée par le fabricant.
comprise entre 2 g et 20 g de tétrahydroborate de
sodium (NaBH,) en pastilles ou en poudre et 4 g
On peut également préparer une solution étalon d’ar-
d’hydroxyde de sodium (NaOH) en pastilles, et les intro-
senic conformément au mode opératoire prescrit en
duire dans un bécher de 1 litre (6.2.1.1). Ajouter 200 ml
5.11.2.
d’eau (5.1) et mélanger. Transférer quantitativement la
solution dans une fiole jaugée à un trait de 1 000 ml
5.11.2 Peser avec précision 1,320 g $- 0,001 g de
(6.2.1.5), en la filtrant à travers une membrane filtrante à
trioxyde d’arsenic (As,O,) dans un bécher de 50 ml
l’aide d’un appareillage de filtration sous dépression
(6.2.1.1) ajouter 10 ml d’acide chlorhydrique concentré
(6.2.6). Compléter au volume avec de l’eau (5.1) boucher
(5.3) couvrir avec un verre de montre (6.2.1.2) et chauffer
et bien mélanger.
à environ 150 “C sur la plaque chauffante (6.2.5) sous
hotte d’aspiration jusqu’à dissolution complète. Retirer le
Préparer une nouvelle solution tous les jours.
bécher de la plaque chauffante, laisser refroidir, transférer
quantitativement la solution dans une fiole jaugée à un
NOTES
trait de 1 000 ml (6.2.1.5), compléter au volume avec de
l’acide chlorhydrique dilué 1 + 1 (5.4), boucher et bien
4 I! est nécessaire de filtrer la solution pour éliminer les
mélanger.
matières particulaires non dissoutes susceptibles d’obstruer la
tuyauterie ou le mélangeur du système de production d’hy-
peut être conservée dans un flacon en
Cette solution
drures (6.28). L’ajout d’alcali permet de minimiser l’hydrolyse
(6.2.2) pendant une durée maximale d’un
polypropylène
de la solution de tétrahydroborate de sodium.
an.
5 Quelques gouttes d’agent antimoussant peuvent être ajou-
- Le trioxyde d’arsenic est toxi-
AVERTISSEMENT
tées à la solution pour réduire la formation de mousse dans le
que et cancérigène pour l’homme (voir référence
séparateur gaz/liquide du système de production d’hydrures
bibliographique [Il citée dans l’annexe A). Voir
(6.2.8), qui peut perturber la ligne de base.
l’avertissement général sur l’arsenic ou les compo-
6 II convient de conserver la solution dans un flacon en poly-
sés de l’arsenic, juste après le titre de la présente
propylène (6.2.2) si elle n’est pas transférée dans le réservoir à
Norme internationale.
réducteur du système de production d’hydrures (6.2.8) en
continu immédiatement après préparation (voir 8.4.2.2). II y a
lieu de ne pas boucher complètement le flacon pour éviter la
5.12 Solution fille étalon d’arsenic A, correspon-
montée en pression due au lent dégagement d’hydrogène.
dant à 10 mg de As par litre.
---------------------- Page: 6 ----------------------
0 ISO ISO 11041:1996(F)
5.15 Hydroxyde de sodium, solution à 5 g/l.
11 Les échantillonneurs assemblés par vissage peuvent ne
pas être utilisables avec une membrane filtrante en ester de
Peser 5,0 g d’hydroxyde de sodium (NaOH) en pastilles
cellulose et un tampon en cellulose placé en aval. En raison de
dans un bécher de 1 litre (6.2.1 .l). Ajouter 250 ml d’eau
la forte perte de charge d’une membrane filtrante en ester de
(5.1) et mélanger jusqu’à dissolution. Transférer quantita-
cellulose, comparée à celle d’un tampon en cellulose, l’air à
tivement la solution dans une fiole jaugée de 1 000 ml
tendance à suivre le trajet offrant la moindre résistance et à
(6.2.1.5), compléter au volume avec de l’eau, boucher et
passer le long des vis et par les bords du tampon en cellulose,
bien mélanger.
plutôt qu’à travers la membrane filtrante en ester de cellulose.
On peut parfois éliminer les fuites en resserrant les fixations le
plus possible, pour. comprimer et rendre étanches les bords
5.16 Solution détergente de laboratoire, conve-
des tampons en cellulose, mais, sur certains types d’échantil-
nant pour le nettoyage des échantillonneurs et du
lonneurs, cela n’est pas totalement efficace. Les échantillon-
matériel de laboratoire, diluée avec de l’eau (5.1)
neurs assemblés par pression peuvent généralement être
conformément aux instructions du fabricant.
utilisés avec une meilleure fiabilité.
5.17 Gaz de purge inerte, par exemple argon ou
12 Les échantillonneurs faits en matériau non conducteur ont
azote, fourni en bouteille ou sous forme de fluide
des propriétés électrostatiques qui peuvent influencer I’échan-
tillonnage représentatif. Lorsque c’est possible, les influences
cryogénique.
électrostatiques peuvent êt@ réduites en utilisant des échan-
tillons faits en matériau conducteur.
5.18 Air, comprimé et filtré.
NOTE 7 Ce gaz n’est pas nécessaire si la cuve d’absorp-
tion en silice ou en quartz (6.29) utilisée est chauffée 6.1.2 Membranes filtrantes en ester de cellulose
électriquement.
et tampons en cellulose placés en aval, de diamètre
approprié pour I’échantillonneur choisi (6.1.1).
5.19 Acétylène, en bouteille.
La masse d’arsenic contenue dans une membrane fil-
NOTE 8 Ce gaz n’est pas nécessaire si la cuve d’absorp- trante en ester de cellulose et dans un tampon en cel-
tion en silice ou en quartz (6.2.9) utilisée est chauffée
lulose placé en aval doit être inférieure à 0,Ol pg.
électriquement.
6.1.2.1 Les membranes filtrantes en ester de cellu-
lose doivent présenter une efficacité supérieure ou
égale à 99 % pour les particules d’un diamètre aérody-
namique moyen de 0,3 prn (voir ISO 7708:1995, para-
6 Appareillage
graphe 2.2).
6.1 Matériel d’échantillonnage 6.1.2.2 Les tampons en cellulose placés en aval
doivent être imprégnés de carbonate de sodium dans
une zone où l’on sait que la contamination par I’ar-
6.1 .l Échantillonneurs, permettant de prélever la
senic est faible, conformément au mode opératoire
fraction inhalable des particules d’aérosol (voir 7.1 .l),
telles que définies dans I’ISO 7708, pouvant être utili- suivant.
sés avec les membranes filtrantes en ester de cellu-
Placer les tampons en cellulose sur une feuille de
lose et les tampons en cellulose placés en aval (6.1.2),
polytétrafluoroéthylène (PTFE) propre ou sur une sur-
et compatibles avec les pompes de prélèvement
face similaire, plane et inerte (6.2.4). Établir le volume
(6.1.3) utilisées.
de la solution de carbonate de sodium (5.2) juste
nécessaire pour mouiller tout le tampon en cellulose,
NOTES
après avoir laissé la solution s’étaler pendant quelques
9 Différents termes sont utilisés pour décrire les échan- minutes. Disposer ce volume de solution de carbonate
tillonneurs conçus pour recueillir la fraction inhalable des
de sodium sur chaque tampon en cellulose et laisser
particules d’aérosol, par exemple têtes d’échantillonnage, sys-
sécher plusieurs heures à température ambiante.
tèmes porte-filtres, cassettes.
Conserver les tampons en cellulose imprégnés de
carbonate de sodium dans un récipient étanche et les
En général, les caractéristiques de prélèvement des échan-
10
utiliser dans la semaine qui suit leur préparation.
tillonneurs de la fraction inhalable sont telles que les matières
particulaires recueillies sur le filtre représentent la fraction
NOTES
inhalable des particules en suspension; celles qui se déposent
sur les parois internes de I’échantillonneur ne sont pas prises
13 Le volume de solution de carbonate de sodium nécessaire
en considération. Toutefois, certains échantillonneurs sont
pour imprégner les tampons en cellulose placés en aval est
conçus de sorte que les particules en suspension qui passent
typiquement de 175 PI pour un tampon de 25 mm de diamètre
par l’orifice (les orifices) d’entrée constituent la fraction
et de 400 ~1 pour un tampon de 37 mm de diamètre.
inhalable; dans ce cas, les matières particulaires déposées sur
les parois internes de I’échantillonneur font partie de
14 On peut réduire la durée de séchage des tampons en
l’échantillon. Certains échantillonneurs de ce type intègrent une
cassette filtrante interne, qui peut être retirée pour permettre cellulose imprégnés de carbonate de sodium en les plaçant
dans une étuve à 40 “C pendant 45 min.
de recueillir facilement ces matières.
5
---------------------- Page: 7 ----------------------
@ ISO
ISO 11041:1996(F)
15 Les filtres en fibres de verre ou de quartz imprégnés de
6.1.6 Thermomètre, de 0 “C à 50 OC, gradué tous
carbonate de sodium conviennent également pour recueillir les
les 1 “C ou moins, pour le mesurage de la tempéra-
vapeurs de trioxyde d’arsenic (voir référence bibliographique [4]
ture atmosphérique (voir 7.1.3).
citée dans l’annexe A) et peuvent être utilisés au même titre
que les membranes filtrantes en ester de cellulose et les
6.1.7 Baromètre, pour le mesurage de la pression
tampons en cellulose imprégnés de carbonate de sodium. Les
atmosphérique (voir 7.1.3).
filtres en fibres de verre ou de quartz ne sont pas dissous par le
mode opératoire de dissolution d’échantillon prescrit en 8.2.2,
mais ce dernier peut être modifié afin de permettre leur
6.2 Appareillage d’analyse ou de laboratoire
utilisation (voir note 33).
Matériel courant de laboratoire, et
6.1.3 Pompes de prélèvement, conformes aux
prescriptions de la EN 1232, à débit réglable, munies
6.2.1 Verrerie, en verre borosilicaté 3.3 conforme
d’un débitmètre ou d’un indicateur de défaut de débit,
aux prescriptions de I’ISO 3585.
permettant de maintenir le débit approprié (voir 7.1 .l)
dans les limites de + 5 % de la valeur nominale pen-
NOTE 20 II est préférable de réserver un jeu de verrerie
dant toute la période d’échantillonnage (voir 7.1.2). pour l’analyse de l’arsenic par cette méthode. Le mode
opératoire de nettoyage prescrit en 8.1.4 peut entraîner un
Pour l’échantillonnage individuel, les pompes doivent
nettoyage insuffisant de la verrerie très contaminée utilisée
pouvoir être portées par une personne sans la gêner
en usage général.
dans son travail. Les pompes doivent fournir un débit
sans pulsation (si nécessaire, un amortisseur de pulsa-
6.2.1.1 Béchers, d’une capacité de 50 ml pour la
tions doit être incorporé entre I’échantillonneur et la
dissolution des membranes filtrantes en ester de
pompe, aussi près que possible de la pompe).
cellulose et des tampons en cellulose placés en aval,
du diamètre utilisé dans I’échantillonneur (voir 8.2.2),
NOTE 16 Des pompes de prélèvement à débit stabilisé
peuvent être nécessaires pour maintenir le débit dans les et pour la préparation de la solution mère étalon
limites prescrites en 6.1.3.
d’arsenic (5.11.2); d’une capacité de 250 ml pour la
préparation de la solution de carbonate de sodium
6.1.4 Débitmètre portable, permettant de mesurer (5.2) et de la solution d’iodure de potassium (5.9); et
le débit approprié (voir 7.1 .l) dans les limites de d’une capacité de 1 litre pour la préparation de la
+ 5 %, étalonné à l’aide d’un étalon primaire, c’est- solution de tétrahydroborate de sodium (5.14) et de la
à-dire un débitmètre dont la precision est traçable vis- solution d’hydroxyde de sodium (5.15).
à-vis des étalons nationaux.
6.2.1.2 Verres de montre, s’adaptant aux béchers
de 50 ml (6.2.1 .l).
NOTES
17 Le débitmètre incorporé dans la pompe de prélèvement
6.2.1.3 Pipettes à un trait, conformes aux prescrip-
peut être utilisé à condition d’avoir une sensibilité appropriée,
tions de I’ISO 648, remplissant la même fonction que
d’avoir été étalonné à l’aide d’un étalon primaire avec un
les instruments volumétriques à piston (6.2.3).
échantillonneur chargé en ligne, et à condition d’être lu quand il
est en position verticale s’il est du type débitmètre à bille.
6.2.1.4 Éprouvettes graduées à pied, de diffé-
Toutefois, il est important de vérifier l’absence de fuites dans le
rentes capacités comprises entre 10 ml et 1 litre.
train d’échantillonnage, entre I’échantillonneur et le débitmètre,
car dans ce cas un débitmètre situé dans la pompe de
prélèvement ou en ligne indiquera un débit erroné. 6.2.1.5 Fioles jaugées à un trait, de différentes
capacités comprises entre 10 ml et 2 000 ml,
18 Un débitmètre à bulle de savon peut être utilisé comme
conformes aux prescriptions de I’ISO 1042.
étalon primaire, à condition que sa précision soit traçable vis-
à-vis des étalons nationaux.
6.2.2 Flacons en polypropyiène, d’une capacité de
1 litre.
19 Le cas échéant (voir 7.1.3.2), il convient d’enregistrer la
température et la pression atmosphériques auxquelles le
NOTE 21 Les flacons réalisés dans d’autres matières plas-
débitmètre a été étalonné.
tiques peuvent être utilisés, à condition qu’ils conviennent
pour l’utilisation prévue (
...
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