ISO 9174:1990
(Main)Water quality — Determination of total chromium — Atomic absorption spectrometric methods
Water quality — Determination of total chromium — Atomic absorption spectrometric methods
Qualité de l'eau — Dosage du chrome total — Méthodes par spectrométrie d'absorption atomique
Kakovost vode - Določanje skupnega kroma - Atomske absorpcijske spektrometrijske metode
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IS0
I N TE R NAT I O NA L
STANDARD 91 74
First edition
1990-04-1 5
Water quality - Determination of total
chromium - Atomic absorption spectrometric
methods
Qualité de l'eau - Dosage du chrome total - Méthodes par
spectrométrie d'absorption atomique
Reference number
IS0 9 1 74: 1990( E)
---------------------- Page: 1 ----------------------
IS0 9174:1990(E)
Foreworc
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, govern-
mental 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 Interna-
tional Standard requires approval by at least 75 % of the member bodies
casting a vote.
International Standard IS0 9174 was prepared by Technical Committee
ISO/TC 147, Water qualify.
Q IS0 1990
All rights reserved. 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
permisslon in writing from the publisher.
International Organization for standardization
Case Postale 56 CH-I211 Genève 20 Switzerland
Printed in Switzerland
ii
---------------------- Page: 2 ----------------------
IS0 91 74:1990(E)
Introduction
Chromium may occur in water in the oxydation states III and VI. The two
methods described determine total chromium in both oxidation states,
either as acid soluble chromium or as soluble chromium, depending on
the sample pre-treatment. The method chosen depends on the concen-
tration of chromium in the water to be examined.
iii
---------------------- Page: 3 ----------------------
- ~ - - ~ -~
INTERNATIONAL STANDARD
IS0 91 741 990( E)
Water quality - Determination of total chromium - Atomic
absorption spectrometric methods
Section I: General
1.1 Scope 1.2 Normative references
This International Standard specifies two methods
for the determination of total chromium in water by
atomic absorption spectrometry. The two methods
are covered in separate sections as follows.
The following standards contain provisions which,
through reference in this text, constitute provisions
Section 2: Method A - Determination of total
of this International Standard. At the time of publi-
chromium by flame atomic absorption spectrom-
cation, the editions indicated were valid. All stand-
etry.
ards are subject to revision, and parties to
agreements based on this International Standard
Section 3: Method B - Determination of total
are encouraged to investigate the possibility of ap-
chromium by electrothermal atomization atomic
plying the most recent editions of the standards in-
absorption spectrometry.
dicated below. Members of IEC and IS0 maintain
reg i st e rs of cu r re n t I y va I id 1 n t e r n at i on a I St a n d a rd s.
Method A is applicable to the analysis of water and
waste water when the concentration range is be-
IS0 5667-2:1982, Water quality - Sampling -
tween 0,5 mg/l and 20 mg/l of chromium. When the
Part 2: Guidance on sampling techniques.
concentration is below 0,5 mg/l the determination
can be carried out after carefully evaporating an
IS0 5667-3:1985, Water quality - Sampling -
acidified sample to small bulk, taking care to avoid
Part 3: Guidance on the preservation and handling
the formation of a precipitate.
of samples.
IMPORTANT - The use of evaporation will increase
the effect of interfering substances and therefore for
concentrations below 0,l mg/l method B is given.
For interferences see clause 2.7.
Method B is applicable to the analysis of water and
waste water when the concentration range is be-
tween 5 pg/l and 100 pg/l of chromium by injecting
a sample volume of 20 pg/1. It is applicable to the
determination of higher concentrations by using a
smaller sample volume.
For interferences see clause 3.7.
1
---------------------- Page: 4 ----------------------
IS0 91 74: 1 990( E)
Section 2: Methode A - Determination of total chromium by flame atomic
absorption spectrometry
Store this solution in either polyethylene or
2.1 Principle
borosilicate glass containers at room temperature.
The solution is stable at room temperature for
The method is based on the atomic absorption
1 year if it is stored in the dark and has a pH be-
spectrometric measurement of the chromium con-
tween l and 2.
tent of the acidified sample in a nitrous
oxide/acetylene flame. Measurement at a wave-
NOTE 1 Chromium stock solutions are commercially
length of 357,9 nm. Addition of lanthanum to reduce
available.
matrix interferences.
2.2.6.2 Chromium, standard solution containing
50 pg of Cr per millilitre.
2.2 Reagents
Pipette 50 ml of the chromium stock solution
All reagents shall be of recognized analytical grade.
(2.2.6.1) into a 1 O00 ml one-mark volumetric flask.
Use deionized water or water distilled from an all e
Add 1 ml of nitric acid (2.2.2), make up to the mark
glass apparatus. The water used for blank determi-
with water and mix.
nations and for preparing reagents and standard
h
solutions shall have a chromium content that is
Store this solution in either polyethylene or
negligible compared with the smallest concen-
borosilicate glass containers at room temperature.
trations to be determined in the samples.
The solution is stable at room temperature for
1 month if it is stored in the dark.
2.2.1 Hydrochloric acid, p w 1,18 g/ml.
2.3 Apparatus
2.2.2 Nitric acid, p B 1,42 g/ml
Usual laboratory apparatus and
2.2.3 Nitric acid, c(HN0,) = 1,5 mol/l.
2.3.1 Atomic absorption spectrometer, equipped
with a chromium hollow cathode lamp and a nitrous
Add 100 ml of nitric acid (2.2.2) to 600 ml of water
oxide/acetylene burner, and operated according to
and dilute to 1 O00 ml.
the manufacturer's instructions.
2.2.4 Hydrogen peroxide, 30 YO (rnlrn) solution.
CAUTION - It is essential that the manufacturer's
safety recommendations are strictly observed when
using the nitrous oxidelacetylene flame.
2.2.5 Lanthanum chloride, (LaCl& solution con-
a
taining 20 g of La per litre.
2.3.2 Glassware.
Dissolve 23,5 g of lanthanum oxide (La,O,), in
200 ml of the hydrochloric acid (2.2.1), dilute to
Before use carefully soak all glassware for 24 h in
1 O00 ml with water and mix.
the nitric acid (2.2.3) then rinse thoroughly with wa-
ter.
CAUTION - Appropriate precautions must be ob-
served when preparing this solution because the re- IMPORTANT - Do not use glassware which has
been cleaned with chromic acid.
action of La203 with HCI Is strongly exothermic.
2.3.3 Membrane filters, of nominal pore diameter
2.2.6 Chromium solutions
0,45 pm, washed thoroughly with nitric acid (2.2.3)
and rinsed with water (see clause 2.2).
2.2.6.1 Chromium, stock solution containing
1,000 g of Cr per litre.
2.4 Sampllng and preparation of test
Dry a portion of potassium dichromate (K2Cr207) at
portions
105 OC& 2 "C for 2 h. Cool and dissolve
2,825 g & 0,001 g of the dried potassium dichromate
2.4.1 Collect samples in polyethylene or
in water, add 5 ml of nitric acid (2.2.2) and dilute to
borosi I icate g I ass containers which have been pre-
1 O00 ml with water in a one-mark volumetric flask.
viously cleaned with nitric acid (2.2.3) and then
rinsed with water.
1 ml of this standard solution contains 1,OO mg of Cr.
2
---------------------- Page: 5 ----------------------
IS0 91 74:1990( E)
2.4.2 Acid-soluble chromium of 0,5 mg/l, 1 mg/l, 2,5 mg/l, 5 mg/l and 10 mg/l re-
spectively.
2.4.2.1 Treat the samples by addition of sufficient
nitric acid (2.2.2), immediately after collection, to
2.5.3 Calibration
adjust the pH value to between 1 and 2.
Set up the instrument according to the manufactur-
2.4.2.2 To 90 ml of the acidified sample, or another
er's instructions (A = 357,9 nm) using a nitrous
suitable aliquot according to the expected concen-
oxide/acetylene flame.
tration, add 1 ml of hydrogen peroxide (2.2.4) and
Aspirate a calibration solution (2.5.2) and optimize
1 ml of nitric acid (2.2.2). Boil and evaporate to a
the aspiration, the burner height and flame condi-
volume of approximately 50 ml.
tions. Adjust the response of the instrument to zero
IMPORTANT - It is essential that the sample is not
absorbance with water.
reduced to dryness.
Aspirate the set of calibration solutions (2.5.2) and,
as a zero member, the blank solution (2,5.1). Plot a
2.4.2.3 Add 10 ml of the nitric acid (2.2.3) to the
graph having the chromium concentrations of the
evaporated solution. Transfer the solution to a
calibration solutions in milligrams per litre as ab-
100 ml one-mark volumetric flask. Pipette 10 ml of
scissa and the corresponding absorbance values as
e
the lanthanum chloride solution (2.2.5) into the flask,
ordinate.
dilute to the mark with water (see clause 2.2) and
mix.
2.5.4 Test portion measurement
2.4.3 Soluble chromium
Aspirate the prepared test portion (2.4.2 or 2.4.3) into
the flame and measure the absorbance for chro-
2.4.3.1 Filter the sample through a membrane filter
mium. After each measurement aspirate water {see
(2.3.3), as soon as possible after collection, and
clause 2.2) and re-adjust the zero if necessary.
acidify the filtrate immediately with nitric acid
(2.2.2) to give a pH between 1 and 2.
2.6 Expression of results
2.4.3.2 Pipette 10 ml of the lanthanum chloride sol-
ution (2.2.5) into a 100 ml one-mark volumetric flask
and make up to the mark with the acidified filtrate
2.6.1 By reference to the calibration graph ob-
(2.4.3.1), or other suitable aliquot according to the
tained (see 2.5.3) determine the concentration of
expecte'd concentration, and mix.
chromium corresponding to the absorbances of the
test p
...
SLOVENSKI STANDARD
SIST ISO 9174:1996
01-junij-1996
.DNRYRVWYRGH'RORþDQMHVNXSQHJDNURPD$WRPVNHDEVRUSFLMVNH
VSHNWURPHWULMVNHPHWRGH
Water quality -- Determination of total chromium -- Atomic absorption spectrometric
methods
Qualité de l'eau -- Dosage du chrome total -- Méthodes par spectrométrie d'absorption
atomique
Ta slovenski standard je istoveten z: ISO 9174:1990
ICS:
13.060.50 3UHLVNDYDYRGHQDNHPLþQH Examination of water for
VQRYL chemical substances
SIST ISO 9174:1996 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
---------------------- Page: 1 ----------------------
SIST ISO 9174:1996
---------------------- Page: 2 ----------------------
SIST ISO 9174:1996
IS0
I N TE R NAT I O NA L
STANDARD 91 74
First edition
1990-04-1 5
Water quality - Determination of total
chromium - Atomic absorption spectrometric
methods
Qualité de l'eau - Dosage du chrome total - Méthodes par
spectrométrie d'absorption atomique
Reference number
IS0 9 1 74: 1990( E)
---------------------- Page: 3 ----------------------
SIST ISO 9174:1996
IS0 9174:1990(E)
Foreworc
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, govern-
mental 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 Interna-
tional Standard requires approval by at least 75 % of the member bodies
casting a vote.
International Standard IS0 9174 was prepared by Technical Committee
ISO/TC 147, Water qualify.
Q IS0 1990
All rights reserved. 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
permisslon in writing from the publisher.
International Organization for standardization
Case Postale 56 CH-I211 Genève 20 Switzerland
Printed in Switzerland
ii
---------------------- Page: 4 ----------------------
SIST ISO 9174:1996
IS0 91 74:1990(E)
Introduction
Chromium may occur in water in the oxydation states III and VI. The two
methods described determine total chromium in both oxidation states,
either as acid soluble chromium or as soluble chromium, depending on
the sample pre-treatment. The method chosen depends on the concen-
tration of chromium in the water to be examined.
iii
---------------------- Page: 5 ----------------------
SIST ISO 9174:1996
---------------------- Page: 6 ----------------------
SIST ISO 9174:1996
- ~ - - ~ -~
INTERNATIONAL STANDARD
IS0 91 741 990( E)
Water quality - Determination of total chromium - Atomic
absorption spectrometric methods
Section I: General
1.1 Scope 1.2 Normative references
This International Standard specifies two methods
for the determination of total chromium in water by
atomic absorption spectrometry. The two methods
are covered in separate sections as follows.
The following standards contain provisions which,
through reference in this text, constitute provisions
Section 2: Method A - Determination of total
of this International Standard. At the time of publi-
chromium by flame atomic absorption spectrom-
cation, the editions indicated were valid. All stand-
etry.
ards are subject to revision, and parties to
agreements based on this International Standard
Section 3: Method B - Determination of total
are encouraged to investigate the possibility of ap-
chromium by electrothermal atomization atomic
plying the most recent editions of the standards in-
absorption spectrometry.
dicated below. Members of IEC and IS0 maintain
reg i st e rs of cu r re n t I y va I id 1 n t e r n at i on a I St a n d a rd s.
Method A is applicable to the analysis of water and
waste water when the concentration range is be-
IS0 5667-2:1982, Water quality - Sampling -
tween 0,5 mg/l and 20 mg/l of chromium. When the
Part 2: Guidance on sampling techniques.
concentration is below 0,5 mg/l the determination
can be carried out after carefully evaporating an
IS0 5667-3:1985, Water quality - Sampling -
acidified sample to small bulk, taking care to avoid
Part 3: Guidance on the preservation and handling
the formation of a precipitate.
of samples.
IMPORTANT - The use of evaporation will increase
the effect of interfering substances and therefore for
concentrations below 0,l mg/l method B is given.
For interferences see clause 2.7.
Method B is applicable to the analysis of water and
waste water when the concentration range is be-
tween 5 pg/l and 100 pg/l of chromium by injecting
a sample volume of 20 pg/1. It is applicable to the
determination of higher concentrations by using a
smaller sample volume.
For interferences see clause 3.7.
1
---------------------- Page: 7 ----------------------
SIST ISO 9174:1996
IS0 91 74: 1 990( E)
Section 2: Methode A - Determination of total chromium by flame atomic
absorption spectrometry
Store this solution in either polyethylene or
2.1 Principle
borosilicate glass containers at room temperature.
The solution is stable at room temperature for
The method is based on the atomic absorption
1 year if it is stored in the dark and has a pH be-
spectrometric measurement of the chromium con-
tween l and 2.
tent of the acidified sample in a nitrous
oxide/acetylene flame. Measurement at a wave-
NOTE 1 Chromium stock solutions are commercially
length of 357,9 nm. Addition of lanthanum to reduce
available.
matrix interferences.
2.2.6.2 Chromium, standard solution containing
50 pg of Cr per millilitre.
2.2 Reagents
Pipette 50 ml of the chromium stock solution
All reagents shall be of recognized analytical grade.
(2.2.6.1) into a 1 O00 ml one-mark volumetric flask.
Use deionized water or water distilled from an all e
Add 1 ml of nitric acid (2.2.2), make up to the mark
glass apparatus. The water used for blank determi-
with water and mix.
nations and for preparing reagents and standard
h
solutions shall have a chromium content that is
Store this solution in either polyethylene or
negligible compared with the smallest concen-
borosilicate glass containers at room temperature.
trations to be determined in the samples.
The solution is stable at room temperature for
1 month if it is stored in the dark.
2.2.1 Hydrochloric acid, p w 1,18 g/ml.
2.3 Apparatus
2.2.2 Nitric acid, p B 1,42 g/ml
Usual laboratory apparatus and
2.2.3 Nitric acid, c(HN0,) = 1,5 mol/l.
2.3.1 Atomic absorption spectrometer, equipped
with a chromium hollow cathode lamp and a nitrous
Add 100 ml of nitric acid (2.2.2) to 600 ml of water
oxide/acetylene burner, and operated according to
and dilute to 1 O00 ml.
the manufacturer's instructions.
2.2.4 Hydrogen peroxide, 30 YO (rnlrn) solution.
CAUTION - It is essential that the manufacturer's
safety recommendations are strictly observed when
using the nitrous oxidelacetylene flame.
2.2.5 Lanthanum chloride, (LaCl& solution con-
a
taining 20 g of La per litre.
2.3.2 Glassware.
Dissolve 23,5 g of lanthanum oxide (La,O,), in
200 ml of the hydrochloric acid (2.2.1), dilute to
Before use carefully soak all glassware for 24 h in
1 O00 ml with water and mix.
the nitric acid (2.2.3) then rinse thoroughly with wa-
ter.
CAUTION - Appropriate precautions must be ob-
served when preparing this solution because the re- IMPORTANT - Do not use glassware which has
been cleaned with chromic acid.
action of La203 with HCI Is strongly exothermic.
2.3.3 Membrane filters, of nominal pore diameter
2.2.6 Chromium solutions
0,45 pm, washed thoroughly with nitric acid (2.2.3)
and rinsed with water (see clause 2.2).
2.2.6.1 Chromium, stock solution containing
1,000 g of Cr per litre.
2.4 Sampllng and preparation of test
Dry a portion of potassium dichromate (K2Cr207) at
portions
105 OC& 2 "C for 2 h. Cool and dissolve
2,825 g & 0,001 g of the dried potassium dichromate
2.4.1 Collect samples in polyethylene or
in water, add 5 ml of nitric acid (2.2.2) and dilute to
borosi I icate g I ass containers which have been pre-
1 O00 ml with water in a one-mark volumetric flask.
viously cleaned with nitric acid (2.2.3) and then
rinsed with water.
1 ml of this standard solution contains 1,OO mg of Cr.
2
---------------------- Page: 8 ----------------------
SIST ISO 9174:1996
IS0 91 74:1990( E)
2.4.2 Acid-soluble chromium of 0,5 mg/l, 1 mg/l, 2,5 mg/l, 5 mg/l and 10 mg/l re-
spectively.
2.4.2.1 Treat the samples by addition of sufficient
nitric acid (2.2.2), immediately after collection, to
2.5.3 Calibration
adjust the pH value to between 1 and 2.
Set up the instrument according to the manufactur-
2.4.2.2 To 90 ml of the acidified sample, or another
er's instructions (A = 357,9 nm) using a nitrous
suitable aliquot according to the expected concen-
oxide/acetylene flame.
tration, add 1 ml of hydrogen peroxide (2.2.4) and
Aspirate a calibration solution (2.5.2) and optimize
1 ml of nitric acid (2.2.2). Boil and evaporate to a
the aspiration, the burner height and flame condi-
volume of approximately 50 ml.
tions. Adjust the response of the instrument to zero
IMPORTANT - It is essential that the sample is not
absorbance with water.
reduced to dryness.
Aspirate the set of calibration solutions (2.5.2) and,
as a zero member, the blank solution (2,5.1). Plot a
2.4.2.3 Add 10 ml of the nitric acid (2.2.3) to the
graph having the chromium concentrations of the
evaporated solution. Transfer the solution to a
calibration solutions in milligrams per litre as ab-
100 ml one-mark volumetric flask. Pipette 10 ml of
scissa and the corresponding absorbance values as
e
the lanthanum chloride solution (2.2.5) into the flask,
ordinate.
dilute to the mark with water (see clause 2.2) and
mix.
2.5.4 Test portion measurement
2.4.3 Soluble chromium
Aspirate the prepared test portion (2.4.2 or 2.4.3) into
the flame and measure the absorbance for chro-
2.4.3.1 Filter the sample through a membrane filter
mium. After each measurement aspirate water {see
(2.3.3), as soon as possible after collection, and
claus
...
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