SIST EN ISO 14403:2003
(Main)Water quality - Determination of total cyanide and free cyanide by continuous flow analysis (ISO 14403:2002)
Water quality - Determination of total cyanide and free cyanide by continuous flow analysis (ISO 14403:2002)
Migrated from Progress Sheet (TC Comment) (2000-07-10): new TD 49 in BP (bli 991125)
Wasserbeschaffenheit - Bestimmung von Gesamtcyanid und freiem Cyanid mit der kontinuierlichen Fließanalytik (ISO 14403:2002)
Diese Internationale Norm legt Verfahren für die Bestimmung von Cyaniden in verschiedenen Wässern (wie z. B. Grund-, Trink-, Oberflächen-, Sicker- und Abwasser) mit Cyanid-Massenkonzentrationen (bezogen auf Cyanid-Ionen) von üblicherweise über 3 µg/l fest. Diese Norm beinhaltet ein CFA-Verfahren für Massenkonzentrationen im Bereich von 10 µg/l bis 100 µg/l. Der Anwendungsbereich darf durch Änderung der Arbeitsbedingungen angepasst werden.
ANMERKUNG Meerwasser kann nach Anpassung von Reagenz- und Bezugslösungen an den Salzgehalt der Proben bei Änderungen in der Empfindlichkeit analysiert werden.
Qualité de l'eau - Dosage des cyanures totaux et des cyanures libres par analyse en flux continu (ISO 14403:2002)
La présente Norme internationale spécifie des méthodes pour le dosage des cyanures présents dans divers types d'eau (tels qu'eau souterraine, eau potable, eau de surface, lixiviat et eaux usées) en concentrations généralement supérieures à 3 µg/l, exprimées en ions cyanure. La méthode CFA est applicable à une gamme de concentrations comprises entre 10 µg/l et 100 µg/l. La gamme d'application peut être modifiée en faisant varier les conditions de fonctionnement.
NOTE L'eau de mer peut être analysée avec des changements de sensibilité et l'adaptation des réactifs et des solutions d'étalonnage à la salinité des échantillons.
Kakovost vode - Določevanje celotnega in prostega cianida z neprekinjeno pretočno analizo (ISO 14403:2002)
General Information
Relations
Standards Content (Sample)
SLOVENSKI STANDARD
SIST EN ISO 14403:2003
01-maj-2003
.DNRYRVWYRGH'RORþHYDQMHFHORWQHJDLQSURVWHJDFLDQLGD]QHSUHNLQMHQR
SUHWRþQRDQDOL]R ,62
Water quality - Determination of total cyanide and free cyanide by continuous flow
analysis (ISO 14403:2002)
Wasserbeschaffenheit - Bestimmung von Gesamtcyanid und freiem Cyanid mit der
kontinuierlichen Fließanalytik (ISO 14403:2002)
Qualité de l'eau - Dosage des cyanures totaux et des cyanures libres par analyse en flux
continu (ISO 14403:2002)
Ta slovenski standard je istoveten z: EN ISO 14403:2002
ICS:
13.060.50 3UHLVNDYDYRGHQDNHPLþQH Examination of water for
VQRYL chemical substances
SIST EN ISO 14403:2003 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
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SIST EN ISO 14403:2003
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SIST EN ISO 14403:2003
EUROPEAN STANDARD
EN ISO 14403
NORME EUROPÉENNE
EUROPÄISCHE NORM
March 2002
ICS 13.060.01
English version
Water quality - Determination of total cyanide and free cyanide
by continuous flow analysis (ISO 14403:2002)
Qualité de l'eau - Dosage des cyanures totaux et des Wasserbeschaffenheit - Bestimmung von Gesamtcyanid
cyanures libres par analyse en flux continu (ISO und freiem Cyanid mit der kontinuierlichen Fließanalytik
14403:2002) (ISO 14403:2002)
This European Standard was approved by CEN on 1 March 2002.
CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European
Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such national
standards may be obtained on application to the Management Centre or to any CEN member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by translation
under the responsibility of a CEN member into its own language and notified to the Management Centre has the same status as the official
versions.
CEN members are the national standards bodies of Austria, Belgium, Czech Republic, Denmark, Finland, France, Germany, Greece,
Iceland, Ireland, Italy, Luxembourg, Malta, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
Management Centre: rue de Stassart, 36 B-1050 Brussels
© 2002 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 14403:2002 E
worldwide for CEN national Members.
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SIST EN ISO 14403:2003
EN ISO 14403:2002 (E)
CORRECTED 2002-04-17
Foreword
This document (ISO 14403:2002) has been prepared by Technical Committee ISO/TC 147
"Water quality" in collaboration with Technical Committee CEN/TC 230 "Water analysis", the
secretariat of which is held by DIN.
This European Standard shall be given the status of a national standard, either by publication
of an identical text or by endorsement, at the latest by September 2002, and conflicting
national standards shall be withdrawn at the latest by September 2002.
According to the CEN/CENELEC Internal Regulations, the national standards organizations of
the following countries are bound to implement this European Standard: Austria, Belgium,
Czech Republic, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy,
Luxembourg, Malta, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and the
United Kingdom.
Endorsement notice
The text of the International Standard ISO 14403:2002 has been approved by CEN as a
European Standard without any modifications.
NOTE Normative references to International Standards are listed in annex ZA (normative).
2
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SIST EN ISO 14403:2003
EN ISO 14403:2002 (E)
Annex ZA
(normative)
Normative references to International Publicationswith their relevant
European publications
This European Standard incorporates by dated or undated reference, provisions from other
publications. These normative references are cited at the appropriate places in the text, and the
publications are listed hereafter. For dated references, subsequent amendments to or revisions
of any of these publications apply to this European Standard only when incorporated in it by
amendment or revision. For undated references the latest edition of the publication referred to
applies (including amendments).
NOTE Where an International Publication has been modified by common modifications,
indicated by (mod.), the relevant EN/HD applies.
Publication Year Title EN/HD Year
ISO 3696 1987 Water for analytical laboratory use — EN ISO 3696 1995
Specifications and test methods
3
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SIST EN ISO 14403:2003
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SIST EN ISO 14403:2003
INTERNATIONAL ISO
STANDARD 14403
First edition
2002-03-01
Water quality — Determination of total
cyanide and free cyanide by continuous
flow analysis
Qualité de l'eau — Dosage des cyanures totaux et des cyanures libres par
analyse en flux continu
Reference number
ISO 14403:2002(E)
©
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SIST EN ISO 14403:2003
ISO 14403:2002(E)
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SIST EN ISO 14403:2003
ISO 14403:2002(E)
Contents Page
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Interferences . 2
5 Principle . 2
6 Reagents . 3
7 Apparatus . 5
8 Sampling and sample preparation . 9
9 Procedure . 10
10 Calculation . 12
11 Precision and accuracy . 13
12 Test report . 13
Annexes
A Determination of the actual cyanide concentration in potassium cyanide stock solution. 14
B Example for the determination of total cyanide and free cyanide by continuous flow analysis (CFA) with gas
diffusion and amperometric detection . 15
C Results of the interlaboratory trial for cyanide determination. 17
Bibliography. 18
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SIST EN ISO 14403:2003
ISO 14403:2002(E)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO
member bodies). The work of preparing International Standards is normally carried out through ISO 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. ISO collaborates closely with the International Electrotechnical
Commission (IEC) on all matters of electrotechnical standardization.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 3.
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.
Attention is drawn to the possibility that some of the elements of this International Standard may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights.
International Standard ISO 14403 was prepared by Technical Committee ISO/TC 147, Water quality, Subcommittee
SC 2, Physical, chemical, biochemical methods.
Annex A forms a normative part of this International Standard. Annexes B and C are for information only.
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SIST EN ISO 14403:2003
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Introduction
Methods using flow analysis automate wet chemical procedures and are particularly suitable for the processing of
many analytes in water in large sample series at a high analysis frequency.
Analysis can be performed by flow injection analysis (FIA) or continuous flow analysis (CFA). In this International
Standard the latter is specified. The CFA method shares the feature of an automatic dosage of the sample into a flow
system (manifold) where the analytes in the sample react with the reagent solutions on their way through the
manifold. The sample preparation may be integrated in the manifold. The reaction product is measured in a flow
detector (e.g. flow photometer).
It is absolutely essential that the test described in this International Standard be carried out by suitable qualified staff.
It should be investigated whether and to what extend particular problems will require the specification of additional
marginal conditions.
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SIST EN ISO 14403:2003
INTERNATIONAL STANDARD ISO 14403:2002(E)
Water quality — Determination of total cyanide and free cyanide by
continuous flow analysis
WARNING — Persons using this International Standard should be familiar with normal laboratory practice.
This International Standard does not purport to address all of the safety problems, if any, associated with its
use. It is the responsibility of the user to establish appropriate safety and health practices and to ensure
compliance with any national regulatory conditions.
1 Scope
This International Standard specifies methods for the determination of cyanide in various types of water (such as
ground, drinking, surface, leachate and waste water) with cyanide concentrations usually above 3µg/l expressed as
cyanide ions. The CFA method is applicable to a mass concentration range from 10µg/l to 100µg/l. The range of
application may be changed by varying the operation conditions.
NOTE Seawater may be analyzed with changes in sensitivity and adaptation of the reagent and calibration solutions to the
salinity of the samples.
2 Normative references
The following normative documents contain provisions which, through reference in this text, constitute provisions of
this International Standard. For dated references, subsequent amendments to, or revisions of, any of these
publications do not apply. However, parties to agreements based on this International Standard are encouraged to
investigate the possibility of applying the most recent editions of the normative documents indicated below. For
undated references, the latest edition of the normative document referred to applies. Members of ISO and IEC
maintain registers of currently valid International Standards.
ISO 3696:1987, Water for analytical laboratory use — Specification and test methods
ISO 5725-2:1994, Accuracy (trueness and precision) of measurement methods and results — Part 2: Basic method
for the determination of repeatability and reproducibility of a standard measurement method
ISO 8466-1:1990, Water quality — Calibration and evaluation of analytical methods and estimation of performance
characteristics — Part 1: Statistical evaluation of the linear calibration function
3 Terms and definitions
For the purposes of this International Standard, the following terms and definitions apply.
3.1
total cyanide
sum of some organically bound cyanides, free cyanide ions, complex compounds and cyanide bound in simple metal
cyanides, with the exception of cyanide bound in cobalt complexes and of thiocyanate
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3.2
free cyanide
easily liberatable cyanide
sum of cyanide ions and the cyanide bound in simple metal cyanides as determined in accordance with this
International Standard
NOTE Organic cyanides are not included.
4 Interferences
4.1 Interferences by oxidizing agents
Oxidizing agents such as chlorine decompose most of the cyanides. If oxidizing agents are suspected, test for their
presence as given in clause 8.
4.2 Interferences by sulfides
Sulfide concentrations > 60 mg/l affect the colorimetric procedure. If sulfide is suspected, carry out tests for its
presence as given in clause 8.
4.3 Other interferences
When using in-line distillation for separation of the hydrogen cyanide, salt concentrations higher than 10 g/l can
cause clogging of the distillation coil. Dilute these samples prior to measurement in order to overcome this problem.
Under the given distillation conditions aldehydes can transform cyanide to nitrite. Aldehydes can be removed by
adding silver nitrate to the sample.
NOTE The addition of AgNO can alter the ratio of the concentrations of free and total cyanide. The user should evaluate this
3
procedure.
Particulate matter in the sample may lead to clogging of the transport tubes and will interfere with the photometric
measurement. Particles > 0,1 mm should be removed by filtration.
Thiocyanate can slightly interfere and lead to positive bias (9.3.2). Significant interferences can arise from cyanide
impurities in thiocyanate or from inappropriate distillation procedures (7.1).
5Principle
5.1 Determination of total cyanide concentration
Complex bound cyanide is decomposed by UV light in a continuous flow at a pH of 3,8. A UV-B lamp (312 nm) and a
decomposition spiral of borosilicate glass is used to filter off UV light with a wavelength of 290 nm thus preventing the
conversion of thiocyanate into cyanide. Alternatively it is possible to use a long wavelength UV lamp (351 nm), which
does not emit light below 290 nm and which is equipped with a decomposition spiral of quartz glass or
◦
polytetrafluoroethylene (PTFE). The hydrogen cyanide present at pH 3,8 is separated by on-line distillation at 125 C
◦
or by gas diffusion at 30 C across a hydrophobic membrane. The hydrogen cyanide is then determined
photometrically by the reaction of cyanide with chloramine-T to cyanogen chloride. This reacts with pyridine-4-
carbonic acid and 1,3-dimethylbarbituric acid to give a red dye.
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5.2 Determination of free cyanide concentration
The UV lamp is switched off when determining the free cyanide content. During distillation at pH 3,8 for separation of
the hydrogen cyanide present, a zinc sulfate solution is added to the sample flow in order to precipitate any iron
cyanides present as the zinc-cyanoferrate complex. For detection see 5.1.
6Reagents
WARNING — KCN, K Zn(CN) , and their solutions and wastes are toxic. Waste containing these substances
2 4
shall be removed appropriately.
Use only reagents of recognized analytical grade.
6.1 Water, grade 1 according to ISO 3696.
6.2 Hydrochloric acid I, .c(HCl)= 12 mol/l
6.3 Hydrochloric acid II, .c(HCl)= 1 mol/l
6.4 Hydrochloric acid III, .c(HCl)= 0,1 mol/l
6.5 Sodium hydroxide solution I, .c(NaOH)= 2,5 mol/l
6.6 Sodium hydroxide solution II, .c(NaOH)= 1,0 mol/l
6.7 Sodium hydroxide solution III, .c(NaOH)= 0,1 mol/l
6.8 Sodium hydroxide solution IV, .c(NaOH)= 0,01 mol/l
6.9 Surfactant, polyoxyethylene lauryl ether, OH-(CH CH -O) -C H .
2 2 n 18 37
Add 30 g of polyoxyethylene lauryl ether in small quantities to 100 ml of water (6.1) and mix well.
Alternatively use a commercially available solution of the surfactant.
6.10 Citric acid monohydrate, C H O ·H O.
6 8 7 2
6.11 Zinc sulfate heptahydrate, ZnSO ·7H O.
4 2
6.12 Potassium hydrogenphthalate, KHC H O .
8 4 4
6.13 Chloramine-T trihydrate, C H ClNNaO S·3H O.
7 7 2 2
6.14 1,3-Dimethylbarbituric acid, C H N O .
6 8 2 3
6.15 Pyridine-4-carboxylic acid, C H NO .
6 5 2
6.16 Potassium thiocyanate, KSCN.
6.17 Potassium hexacyanoferrate(III), K Fe(CN) .
3 6
6.18 Cyanide standards.
6.18.1 Potassium cyanide stock solution, KCN,ρ(CN)= 100 mg/l(see annexA).
Dissolve 250 mg± 1 mg of potassium cyanide, KCN, in sodium hydroxide solution IV (6.8) in a 1 000 ml graduated
flask and make up to volume with sodium hydroxide solution IV (6.8).
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Alternatively, a potassium tetracyanozincate solution (6.18.2) may be used.
6.18.2 Potassium tetracyanozincate solution, K Zn(CN), .ρ(CN)= 1 000 mg/l± 2 mg/l
2 4
Commercially available.
6.18.3 Cyanide solution I, .ρ(CN)= 10 mg/l
Pipette 1ml of the potassium tetracyanozincate solution I (6.18.2) or 10ml of the potassium cyanide stock solution
(6.18.1) into a 100 ml graduated flask and bring to volume with sodium hydroxide solution IV (6.8).
This solution is stable for 1 week if stored at room temperature.
6.18.4 Calibration solutions.
Prepare at least five calibration solutions with cyanide concentrations, equidistantly distributed over the working
range, by appropriate dilution of the cyanide solution I (6.18.3). If, for example, six calibration solutions should be
prepared, proceed as follows:
Pipette 10 ml of the cyanide solution I (6.18.3) into a 100 ml graduated flask and make up to volume with sodium
hydroxide solution IV (6.8).
Pipette, in 100 ml graduated flasks, 1 ml, 3 ml, 5 ml, 6 ml, 8 ml, or 10 ml, respectively, of the above-mentioned 1 mg/l
cyanide solution and make up to volume with sodium hydroxide solution IV (6.8).
These solutions contain 10µg/l, 30µg/l, 50µg/l, 60µg/l, 80µg/l, and 100µg/l of cyanide, respectively (except for
corrections in the concentration found on titration of the potassium cyanide solution (6.18.1), (see annex A).
◦ ◦
These solutions are stable for 2 days if stored in a refrigerator at 2C5 to C.
6.19 Reagents for the determination of cyanide.
6.19.1 Buffer (pH = 3,8) for distillation and gas diffusion method.
Dissolve 50 g of citric acid (6.10) in 350 ml of water (6.1). Add 120 ml of sodium hydroxide solution I (6.5) and, if
necessary adjust to pH 3,8 with hydrochloric acid II (6.3) or sodium hydroxide solution II (6.6). Dilute to 500 ml with
water.
◦ ◦
This solution is stable for 3 months if stored in a refrigerator at 2C5 to C.
6.19.2 Zinc sulfate solution (only for distillation method).
Dissolve 10 g of zinc sulfate heptahydrate (6.11) in 750 ml of water (6.1), mix and dilute to 1 000 ml with water.
6.19.3 Recipient solution (only for gas diffusion).
Sodium hydroxide solution III (6.7).
6.19.4 Buffer solution for the final photometric determination ()pH= 5,2.
Dissolve 2,3 g of sodium hydroxide (NaOH) in 500 ml of water (6.1). Add 20,5 g of potassium hydrogenphthalate
(6.12) and dilute to approximately 975 ml with water.
If necessary, adjust the pH of the solution to 5,2 with hydrochloric acid II (6.3) or sodium hydroxide solution II (6.6).
Add 1 ml of surfactant (6.9) and make up to 1 000 ml with water.
◦ ◦
This solution is stable for 3 months if stored in a refrigerator at 2C5 to C.
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ISO 14403:2002(E)
6.19.5 Chloramine-T trihydrate solution.
Dissolve 2,0 g± 0,05 g of chloramine-T trihydrate (6.13) in 1 000 ml of water.
◦ ◦
This solution is stable for 3 months if stored in a refrigerator at 2C5 to C.
6.19.6 Colour reagent.
Dilute 7,0 g of sodium hydroxide, NaOH, in 500 ml of water (6.1). Add 16,8 g± 0,1 g of 1,3-dimethylbarbituric acid
(6.14), and 13,6 g± 0,1 g of pyridine-4-carboxylic acid (6.15), and dilute to approximately 975 ml with water (6.1).
If necessary, bring the solution to pH 5,2 with hydrochloric acid II (6.3) or sodium hydroxide solution II (6.6).
◦
Make up to 1 000 ml with water (6.1). Mix this solution intensively (e.g. by using a magnetic stirrer) for 1h at 30 C
and then filter over a pleated filter (e.g. hardened ashless paper).
◦ ◦
This solution is stable for 3 months if stored in a refrigerator at 2C5 to C.
6.20 Standard thiocyanate solution, calculated cyanide concentration: ρ(CN)= 100 mg/l.
Dissolve in a 1 000 ml graduated flask 373 mg±1mg of potassium thiocyanate (6.16) in sodium hydroxide
solution IV (6.8), and make up to volume with sodium hydroxide solution IV (6.8).
◦ ◦
This solution is stable for 2 months if stored in a refrigerator at 2C5 to C.
6.21 Standard potassium hexacyanoferrate(III) solution (red blood alkaline salt).
Calculated cyanide concentration ρ(CN)= 10 mg/l.
Dissolve in a 1 000 ml graduated flask 21,1 mg± 0,1 mg of potassium hexacyanoferrate(III) (6.17) in sodium
hydroxide solution IV (6.8), and make up to volume with sodium hydroxide solution IV (6.8).
◦ ◦
This solution is stable for 2 months if stored in a refrigerator at to .
2C5 C
6.22 Rinsing solution.
Dissolve 2 ml of surfactant (6.9) in 1 000 ml of water.
6.23 Ascorbic acid, C H O .
6 8 6
6.24 Powdered lead carbonate, PbCO .
3
7Apparatus
Usual laboratory apparatus, and
7.1 Continuous flow analysis system for distillation method
A typical system comprises the following components (see Figure 1).
7.1.1 Autosampler, or another device capable of introducing sample reproducibility.
7.1.2 Reagent reservoirs.
7.1.3 Low pulsation pump, having specific chemically inert pump tubes, for flow rates as given in Figure 1 as an
example.
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Key
A Segmentation gas (air)
B Buffer for distillation or gas diffusion (6.19.1)
C Sample
DZnSO solution (6.19.2)
4
E Buffer solution for final photometric determination (6.19.4)
F Resample
G Chloramine-T trihydrate solution (6.19.5)
H Colour reagent (6.19.6)
1 Pump (flow rates in ml/min)
2 Reaction coil (50 cm, ∅int. )1 mm
3 UV decomposition unit (351 nm)
◦
4 Heating bath (30 C)
◦
5 Distillation unit (125 C)
6 Reaction coil (50 cm, ∅int. )1 mm
7 Reaction coil (50 cm, ∅int. )1 mm
◦
8 Heating bath (37 C, 100 cm, ∅int. )1 mm
9 Detector (e.g. 1 cm optical path length), wavelength 590 nm to 610 nm
10 Waste
Figure 1 — Typical continuous flow system for the photometric determination of free
and total cyanide (10µg/l to 100µg/l) with a distillation procedure
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ISO 14403:2002(E)
7.1.4 UV lamp, consisting of one of the following.
351 nm 45 nm 8 W 12 W
a) UV lamp with an emission maximum of , bandwidth , and a power of to , and a digestion
coil made of quartz glass or PTFE with a capacity of approximately 4ml (e.g. 30 or 60 turns with a diameter of
, a tube wall thickness of max. and an internal diameter of or ).
30 mm 1 mm 1 mm 2 mm
b) UV-B lamp with an emission maximum of 312 nm±5nm and a power of 8W to 12W, and a digestion coil made
of borosilicate glass with a capacity of approximately 13 ml (e.g. 45 turns with a diameter of 30 mm, a tube wall
thickness of max. 1mm and an internal diameter of 2mm).
Make sure that no UV light with a wavelength below 290 nm reaches the sample flow in order to avoid the
decomposition of thiocyanate to cyanide.
◦ ◦
7.1.5 In-line distillation device, adjustable to a temperature of 125 C± 1 C with a distillation coil of glass or
polymer material, length of spiral e.g. 80 cm, internal diameter e.g. 1,5 mm.
7.1.6 Manifold, capable of highly reproducible dosing of gas bubbles, sample and reagents, and having appropriate
transport systems and connection assemblies made of chemically inert glass, polymer or metal.
◦ ◦
7.1.7 Heating bath, for colorimetric reaction, adjustable to a temperature of 37 C± 1 C with a coil volume to
4min
allow a sample retention period of approximately .
7.1.8 Photometric detector, with a flow cell, and having a wavelength of range 600 nm± 10 nm.
Use an appropriate optical path length to achieve a minimum absorbance (absolute value) of 0,01 for a 10µg/l
cyanide solution.
7.1.9 Recording unit (e.g. strip chart recorder, integrator or printer/plotter). In general, peak height signals are
measured.
7.2 Continuous flow analysis system for gas diffusion method
A typical system comprises the following components (see Figure 2).
7.2.1 Autosampler, or another device capable of introducing sample reproducibly.
7.2.2 Reagent reservoirs.
7.2.3 Low pulsation pump, having specific chemically inert pump tubes. Figure 2 shows an example of flow rates.
7.2.4 UV lamp, consisting of one of the following.
a) UV lamp with an emission maximum of 351 nm, bandwidth 45 nm, and a power of 8 W to 12 W and having a
digestion coil made of quartz glass or PTFE with a capacity of approximately 4ml (e.g. 30 or 60 turns with a
diameter of 30 mm, a tube wall thickness of max.1 mm and an internal diameter of 1 mm or 2 mm).
b) UV-B lamp with an emission maximum of 312 nm±5nm and a power of 8W to 12W and having a digestion coil
made of borosilicate glass with a capacity of approximately 13 ml (e.g. 45 turns with a diameter of 30 mm, a tube
wall thickness of max 1mm and an internal diameter of 2mm).
Make sure that no UV light with a wavelength below 290 nm reaches the sample flow in order to avoid the
decomposition of thiocyanate to cyanide.
7.2.5 Gas diffusion cell, having a hydrophobic semipermeable membrane made from, for example polypropene or
PTFE, and having a typical thickness of 90µm to 200µm, with a pore size of 0,1µm1 to µm.
◦ ◦
7.2.6 Two heating baths for gas-diffusion temperature stabilization, adjustable to 30 C± 1 C with a coil
capacity of for example 2ml and internal diameter of for example 1mm.
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Key
A Segmentation gas (air)
B Sample
C Buffer for distillation or gas diffusion (6.19.1)
D Recipient solution for gas diffusion (6.19.3)
E Buffer solution for final photometric determination (6.19.4)
F Chloramine-T trihydrate solution (6.19.5)
G Colour reagent (6.19.6)
1 Pump (flow rates in ml/min)
2 Reaction coil (50 cm, ∅int. )1 mm
3 UV decomposition unit (315 nm, 420 cm, ∅int. )2 mm
◦
4 Heating bath (30 C5, 0cm, ∅int. )1mm
5 Gas diffusion unit
6 Reaction coil (50 cm, ∅int. )1 mm
7 Reaction coil (50 cm, ∅int. )1 mm
◦
8 Heating bath (37 C5, 0cm, ∅int. )1mm
9 Detector (e.g. 1 cm optical path length), wave length 590 nm to 610 nm
10 Waste
Figure 2 — Typical continuous flow system for the photometric determination of free
and total cyanide (10µg/l to 100µg/l) with gas-diffusion separation
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8 ISO 2002 – All rights reserved
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