Water quality - Determination of total cyanide and free cyanide using flow analysis (FIA and CFA) - Part 1: Method using flow injection analysis (FIA) (ISO 14403-1:2012)

ISO 14403-1:2012 specifies methods for the determination of cyanide in various types of water (such as ground, drinking, surface, leachate, and waste water) with cyanide concentrations from 2 µg/l to 500 µg/l expressed as cyanide ions in the undiluted sample. The range of application can be changed by varying the operation conditions, e.g. by diluting the original sample or using a different injection volume.
In ISO 14403-1:2012, a suitable mass concentration range from 20 µg/l to 200 µg/l is described.
Seawater can be analysed with possible changes in sensitivity and adaptation of the reagent and calibration solutions to the salinity of the samples.

Wasserbeschaffenheit - Bestimmung von Gesamtcyanid und freiem Cyanid mittels Fließanalytik (FIA und CFA) - Teil 1: Verfahren mittels Fließinjektionsanalyse (FIA) (ISO 14403-1:2012)

Dieser Teil von ISO 14403 legt Verfahren für die Bestimmung von Cyaniden in verschiedenen Wässern (wie
z. B. Grund-, Trink-, Oberflächen-, Sicker- und Abwasser) mit Cyanid-Konzentrationen von 2 µg/l bis 500 µg/l
fest, die als Cyanid-Ionen in der unverdünnten Probe angegeben werden. Der Einsatzbereich kann durch
Änderung der Durchführungsbedingungen angepasst werden, z. B. durch Verdünnen der ursprünglichen
Probe oder Anwendung eines abweichenden Injektionsvolumens.
Der in diesem Teil von ISO 14403 beschriebene geeignete Massenkonzentrationsbereich beträgt 20 µg/l bis
200 µg/l.
Meerwasser kann nach Anpassung von Reagenz- und Bezugslösungen (Kalibrierlösungen) an den Salzgehalt
der Proben sowie mit möglichen Änderungen in der Empfindlichkeit analysiert werden.

Qualité de l'eau - Dosage des cyanures totaux et des cyanures libres par analyse en flux (FIA et CFA) - Partie 1: Méthode par analyse avec injection de flux (FIA) (ISO 14403-1:2012)

L'ISO 14403-1:2012 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 eau résiduaire) en concentrations comprises entre 2 µg/l et 500 µg/l, exprimées en ions cyanure dans l'échantillon non dilué. La gamme d'application peut être modifiée en faisant varier les conditions opératoires, par exemple en diluant l'échantillon d'origine ou en utilisant un volume d'injection différent.
L'ISO 14403-1:2012 décrit une gamme appropriée de concentrations en masse allant de 20 µg/l à 200 µg/l.
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 s pretočno analizo (FIA in CFA) - 1. del: Metoda s pretočno analizo z vbrizgavanjem (FIA) (ISO 14403-1:2012)

Ta del standarda ISO 14403 opisuje metode za določevanje cianida v različnih vrstah vode (na primer podtalni, pitni, površinski, izcedni in odpadni vodi) s koncentracijami cianida od 2 µg/l do 500 µg/l, izraženimi s cianidnimi ioni v nerazredčenem vzorcu. Območje uporabe se lahko spremeni s spreminjanjem operativnih pogojev, npr. z redčenjem izvornega vzorca ali z uporabo drugačne vbrizgane količine. V tem delu standarda ISO 14403 je opisano primerno območje masne koncentracije od 20 µg/l do 200 µg/l. Morska voda se lahko analizira z možnimi spremembami občutljivosti ter prilagajanjem raztopin reagenta in raztopin za kalibracijo slanosti vzorcev.

General Information

Status
Published
Publication Date
14-Jul-2012
Current Stage
6060 - Definitive text made available (DAV) - Publishing
Due Date
15-Jul-2012
Completion Date
15-Jul-2012

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SIST EN ISO 14403-1:2013
01-januar-2013
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SIST EN ISO 14403:2003
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Water quality - Determination of total cyanide and free cyanide using flow analysis (FIA

and CFA) - Part 1: Method using flow injection analysis (FIA) (ISO 14403-1:2012)
Wasserbeschaffenheit - Bestimmung von Gesamtcyanid und freiem Cyanid mittels

Fließanalytik (FIA und CFA) - Teil 1: Verfahren mittels Fließinjektionsanalyse (FIA) (ISO

14403-1:2012)

Qualité de l'eau - Dosage des cyanures totaux et des cyanures libres par analyse en flux

(FIA et CFA) - Partie 1: Méthode par analyse avec injection de flux (FIA) (ISO 14403-

1:2012)
Ta slovenski standard je istoveten z: EN ISO 14403-1:2012
ICS:
13.060.50 3UHLVNDYDYRGHQDNHPLþQH Examination of water for
VQRYL chemical substances
SIST EN ISO 14403-1:2013 en,fr,de

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST EN ISO 14403-1:2013
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SIST EN ISO 14403-1:2013
EUROPEAN STANDARD
EN ISO 14403-1
NORME EUROPÉENNE
EUROPÄISCHE NORM
July 2012
ICS 13.060.50 Supersedes EN ISO 14403:2002
English Version
Water quality - Determination of total cyanide and free cyanide
using flow analysis (FIA and CFA) - Part 1: Method using flow
injection analysis (FIA) (ISO 14403-1:2012)

Qualité de l'eau - Dosage des cyanures totaux et des Wasserbeschaffenheit - Bestimmung von Gesamtcyanid

cyanures libres par analyse en flux continu (FIA et CFA) - und freiem Cyanid mittels Fließanalytik (FIA und CFA) - Teil

Partie 1: Méthode par analyse avec injection de flux (FIA) 1: Verfahren mittels Fließinjektionsanalyse (FIA) (ISO

(ISO 14403-1:2012) 14403-1:2012)
This European Standard was approved by CEN on 13 July 2012.

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 CEN-CENELEC 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 CEN-CENELEC Management Centre has the same

status as the official versions.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,

Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania,

Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and United

Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
Management Centre: Avenue Marnix 17, B-1000 Brussels

© 2012 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 14403-1:2012: E

worldwide for CEN national Members.
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SIST EN ISO 14403-1:2013
EN ISO 14403-1:2012 (E)
Contents Page

Foreword ..............................................................................................................................................................3

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SIST EN ISO 14403-1:2013
EN ISO 14403-1:2012 (E)
Foreword

This document (EN ISO 14403-1:2012) 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 January 2013, and conflicting national standards shall be withdrawn at

the latest by January 2013.

Attention is drawn to the possibility that some of the elements of this document may be the subject of patent

rights. CEN [and/or CENELEC] shall not be held responsible for identifying any or all such patent rights.

This document supersedes EN ISO 14403:2002.

According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following

countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech

Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece,

Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal,

Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the United Kingdom.

Endorsement notice

The text of ISO 14403-1:2012 has been approved by CEN as a EN ISO 14403-1:2012 without any

modification.
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SIST EN ISO 14403-1:2013
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SIST EN ISO 14403-1:2013
INTERNATIONAL ISO
STANDARD 14403-1
First edition
2012-07-15
Water quality — Determination of total
cyanide and free cyanide using flow
analysis (FIA and CFA) —
Part 1:
Method using flow injection analysis (FIA)
Qualité de l’eau — Dosage des cyanures totaux et des cyanures libres
par analyse en flux (FIA et CFA) —
Partie 1: Méthode par analyse avec injection de flux (FIA)
Reference number
ISO 14403-1:2012(E)
ISO 2012
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SIST EN ISO 14403-1:2013
ISO 14403-1:2012(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2012

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 either ISO at the address below or ISO’s

member body in the country of the requester.
ISO copyright office
Case postale 56 • CH-1211 Geneva 20
Tel. + 41 22 749 01 11
Fax + 41 22 749 09 47
E-mail copyright@iso.org
Web www.iso.org
Published in Switzerland
ii © ISO 2012 – All rights reserved
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SIST EN ISO 14403-1:2013
ISO 14403-1:2012(E)
Contents Page

Foreword ............................................................................................................................................................................iv

Introduction ........................................................................................................................................................................ v

1 Scope ...................................................................................................................................................................... 1

2 Normative references ......................................................................................................................................... 1

3 Terms and definitions ......................................................................................................................................... 1

4 Interferences ......................................................................................................................................................... 2

4.1 Interferences by oxidizing agents ................................................................................................................... 2

4.2 Interferences by sulfide, sulfite, nitrite, and carbonyl compounds ....................................................... 2

4.3 Other interferences ............................................................................................................................................. 2

5 Principle ................................................................................................................................................................. 2

5.1 Determination of total cyanide ......................................................................................................................... 2

5.2 Determination of free cyanide .......................................................................................................................... 3

6 Reagents ................................................................................................................................................................ 3

7 Apparatus .............................................................................................................................................................. 5

8 Sampling and sample preparation .................................................................................................................. 6

9 Procedure .............................................................................................................................................................. 7

9.1 Flow system set-up ............................................................................................................................................. 7

9.2 Reagent blank measurement ........................................................................................................................... 7

9.3 Checking the suitability of the flow system ................................................................................................. 7

9.4 Calibration ............................................................................................................................................................. 8

9.5 Sample measurement ......................................................................................................................................... 8

10 Calculation ............................................................................................................................................................ 9

11 Expression of results ......................................................................................................................................... 9

12 Test report ............................................................................................................................................................. 9

Annex A (informative) Examples of flow systems ...................................................................................................10

Annex B (normative) Determination of the real cyanide concentration in the potassium cyanide solution

(6.18.1) .................................................................................................................................................................. 11

Annex C (informative) Performance data ...................................................................................................................12

Bibliography .....................................................................................................................................................................14

© ISO 2012 – All rights reserved iii
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SIST EN ISO 14403-1:2013
ISO 14403-1:2012(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 2.

The main task of technical committees is to prepare International Standards. 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 document may be the subject of patent

rights. ISO shall not be held responsible for identifying any or all such patent rights.

ISO 14403-1 was prepared by Technical Committee ISO/TC 147, Water quality, Subcommittee SC 2, Physical,

chemical and biochemical methods.

ISO 14403 consists of the following parts, under the general title Water quality — Determination of total cyanide

and free cyanide using flow analysis (FIA and CFA):
— Part 1: Method using flow injection analysis (FIA)
— Part 2: Method using continuous flow analysis (CFA)
iv © ISO 2012 – All rights reserved
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SIST EN ISO 14403-1:2013
ISO 14403-1:2012(E)
Introduction

Methods using flow analysis automate wet chemical procedures and are particularly suitable for the processing

of many analytes in water in large series of samples at a high frequency of analysis.

Analysis can be performed by flow injection analysis (FIA) or continuous flow analysis (CFA). Both methods

share the feature of an automatic introduction of the sample into a flow system (manifold) in which analytes

in the sample react with reagent solutions on their way through the manifold. Sample preparation may be

integrated in the manifold. The reaction product is measured in a flow detector (e.g. flow photometer).

See the foreword for a list of parts of this International Standard.

It should be investigated whether and to what extent particular problems require the specification of additional

marginal conditions.
© ISO 2012 – All rights reserved v
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SIST EN ISO 14403-1:2013
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SIST EN ISO 14403-1:2013
INTERNATIONAL STANDARD ISO 14403-1:2012(E)
Water quality — Determination of total cyanide and free cyanide
using flow analysis (FIA and CFA) —
Part 1:
Method using flow injection analysis (FIA)

WARNING — Persons using this part of ISO 14403 should be familiar with normal laboratory practice.

This part of ISO 14403 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.

IMPORTANT — It is absolutely essential that tests conducted according to this part of ISO 14403 be

carried out by suitably trained staff.
1 Scope

This part of ISO 14403 specifies methods for the determination of cyanide in various types of water (such

as ground, drinking, surface, leachate, and waste water) with cyanide concentrations from 2 µg/l to 500 µg/l

expressed as cyanide ions in the undiluted sample. The range of application can be changed by varying the

operation conditions, e.g. by diluting the original sample or using a different injection volume.

In this part of ISO 14403, a suitable mass concentration range from 20 µg/l to 200 µg/l is described.

Seawater can be analysed with possible changes in sensitivity and adaptation of the reagent and calibration

solutions to the salinity of the samples.
2 Normative references

The following referenced documents are indispensable for the application of this document. For dated

references, only the edition cited applies. For undated references, the latest edition of the referenced document

(including any amendments) applies.

ISO 3696, Water for analytical and laboratory use — Specification and test methods

ISO 5667-3, Water quality — Sampling — Part 3: Preservation and handling of water samples

ISO 8466-1, Water quality — Calibration and evaluation of analytical methods and estimation of performance

characteristics — Part 1: Statistical evaluation of the linear calibration function

ISO 8466-2, Water quality — Calibration and evaluation of analytical methods and estimation of performance

characteristics — Part 2: Calibration strategy for non-linear second-order calibration functions

3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
free cyanide
easily liberatable cyanide

sum of cyanide ions and the cyanide bound in weak metal cyanide complexes that liberate HCN at pH 3,8

3.2
total cyanide

free cyanide (3.1), and in addition stronger metal–cyanide complex compounds, with the exception of cyanide bound in

gold, platinum, cobalt, ruthenium, and rhodium complexes from which recovery can be partial

© ISO 2012 – All rights reserved 1
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SIST EN ISO 14403-1:2013
ISO 14403-1:2012(E)
4 Interferences
4.1 Interferences by oxidizing agents

Oxidizing agents such as chlorine decompose most of the cyanides. If the presence of oxidizing agents cannot

be excluded, treat the sample immediately after sampling. Test a drop of the sample with potassium iodide-

starch test paper (KI starch paper); a blue colour indicates the need for treatment. Add sodium thiosulfate, a

few crystals at a time, until a drop of sample produces no colour on the indicator paper.

Carry out a holding time study at the sampling point in order to determine whether the sample is stable for the

time period for preservation and whether the preservation is effective. If this preservation is ineffective, online

measurement instrumentation may be required.
4.2 Interferences by sulfide, sulfite, nitrite, and carbonyl compounds

Interferences by sulfide start at 20 mg/l. If a drop of the sample on lead acetate test paper indicates the

presence of sulfide, treat an additional 25 ml of the stabilized sample (pH >12) to that required for the cyanide

determination with powdered lead carbonate.
Lead sulfide precipitates if the sample contains sulfide.

Repeat this operation until a drop of the treated sample solution does not darken the lead acetate test paper.

Filter the solution through a dry filter paper into a dry beaker, and from the filtrate measure the sample to be

used for analysis. Avoid a large excess of lead and a long contact time in order to minimize loss by complexation

or occlusion of cyanide on the precipitated material.

Aldehydes and ketones can, under certain conditions, absorb cyanide by nucleophilic addition. To avoid this

interference ethylenediamine can be added to the sample.

Interference by nitrite occurs above concentrations of 2 mg/l and can be avoided by addition of sulfamic acid

(6.8) to the buffer (pH 3,8) for the gas diffusion method (6.20.1).
Sulfite interferes above concentrations of 1 mg/l.
4.3 Other interferences

Particulate matter in the sample can lead to clogging of the transport tubes and interferes with the photometric

measurement. Particles of diameter >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 (6.16).
5 Principle
5.1 Determination of total cyanide

Complex-bound cyanide is decomposed by UV light at pH 3,8. A UV-B lamp (emission maximum >310 nm to

400 nm) and a digestion coil of perfluoro (ethylene/propylene) (FEP) or polytetrafluorethylene (PTFE) is used

to filter off UV light with a wavelength <290 nm thus preventing the conversion of thiocyanate into cyanide. A

hydrolytic treatment in a thermoreactor (85 °C) assists the decomposition.

The hydrogen cyanide present at pH 3,8 is separated by diffusion at 30 °C to 40 °C across a hydrophobic

membrane. Hydrogen cyanide is absorbed in a sodium hydroxide solution.

The absorbed cyanide is then determined by the reaction of cyanide with chloramine-T to cyanogen chloride.

This reacts with pyridine-4-carboxylic acid and 1,3-dimethylbarbituric acid to give a red dye.

2 © ISO 2012 – All rights reserved
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SIST EN ISO 14403-1:2013
ISO 14403-1:2012(E)
5.2 Determination of free cyanide

During the procedure specified in 5.1, the UV-B lamp is switched off when determining the free cyanide content.

A thermal decomposition with a citrate and succinate buffer is performed.

To liberate cyanide from the nickel complex, 50 µl tetraethylenepentamine solution (6.11) per 30 ml sample shall

be added prior to the analysis (see Reference [8]).
For detection, see 5.1.
6 Reagents

WARNING — KCN, K Zn(CN) , their solutions, and wastes are toxic. Waste containing these substances

2 4
shall be removed appropriately.
Use only reagents of recognized analytical grade.

Smaller portions of the following solutions can be applied provided the ratios of the prescribed volumes and

mass concentrations are maintained.
6.1 Water, grade 1, as defined in ISO 3696.
6.2 Hydrochloric acid, c(HCl) = 1 mol/l.

6.3 Sodium hydroxide solution I, carrier solution, c(NaOH) = 0,4 mol/l (C2 in Figure A.1).

6.4 Sodium hydroxide solution II, c(NaOH) = 1,0 mol/l.
6.5 Sodium hydroxide solution III, c(NaOH) = 0,01 mol/l.
6.6 Citric acid monohydrate, C H O⋅H O.
6 8 7 2
6.7 Succinic acid, C H O
4 6 4.
6.8 Sulfamic acid, H SO N.
3 3
6.9 Disodium ethylenediamine tetraacetic acid, Na EDTA, C H N O Na .
2 10 14 2 8 2
6.10 Tetraethylenepentamine, C H N .
8 23 5
6.11 Tetraethylenepentamine solution (for free cyanide only).
Dissolve 0,75 g of tetraethylenepentamine (6.10) in 250 ml of water.
This solution is stable for 1 month if stored at room temperature.
6.12 Potassium cyanide, KCN.
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.
© ISO 2012 – All rights reserved 3
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SIST EN ISO 14403-1:2013
ISO 14403-1:2012(E)
6.17 Potassium hexacyanoferrate(III), K Fe(CN) .
3 6
6.18 Cyanide standards.
6.18.1 Potassium cyanide solution, KCN, r = 1 000 mg/l (see Annex B).

Dissolve 2 500 mg ± 1 mg of potassium cyanide, KCN (6.12), in sodium hydroxide solution III (6.5) in a 1 000 ml

volumetric flask, and make up to volume with sodium hydroxide solution III (6.5).

This solution is stable for 6 months at 2 °C to 8 °C.
Alternatively, a potassium tetracyanozincate solution (6.18.2) may be used.

6.18.2 Potassium tetracyanozincate solution, K Zn(CN) , r = 1 000 mg/l ± 2 mg/l, commercially available.

2 4 CN
This solution is stable for 6 months at 2 °C to 8 °C.
6.18.3 Cyanide solution I, r = 10 mg/l.

Pipette 1 ml of the potassium tetracyanozincate solution I (6.18.2) or 1 ml of the potassium cyanide solution

(6.18.1) into a 100 ml volumetric flask, and make up to volume with sodium hydroxide solution III (6.5).

This solution is stable for 1 week if stored at 2 °C to 8 °C.
6.19 Calibration solutions.

Prepare at least five calibration solutions with cyanide concentrations, regularly 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 volumetric flask, and make up to volume with

sodium hydroxide solution III (6.5). This solution contains 1 mg/l cyanide.

Pipette, into 50 ml volumetric flasks, 1 ml, 3 ml, 5 ml, 6 ml, 8 ml, or 10 ml, respectively, of the previously

mentioned 1 mg/l cyanide solution and make up to volume with sodium hydroxide solution III (6.5).

These solutions contain 20 µg/l, 60 µg/l, 100 µg/l, 120 µg/l, 160 µg/l, and 200 µg/l of cyanide, respectively [except

for corrections in the concentration found on titration of the potassium cyanide solution (6.18.1), (see Annex B].

These solutions are stable for 2 d if stored in a refrigerator at 2 °C to 8 °C.
6.20 Reagents for the determination of cyanide.
6.20.1 Buffer, pH 3,8, for gas diffusion method.

Dissolve, in about 350 ml water (6.1), 10,5 g of sodium hydroxide, 12,0 g of Na EDTA (6.9), 15,2 g of succinic

acid (6.7), 27,0 g of citric acid monohydrate (6.6), and 12,5 g of sulfamic acid (6.8). Dilute to 500 ml with water.

This solution is stable for 1 week if stored in a refrigerator (1 °C to 5 °C).

NOTE The decomposition is performed with a citrate and succinate buffer, because this buffer has a higher capacity

at pH 3,8 than a pure citrate buffer. Citrate and EDTA are added, because of their ability to support the decomposition of

hexacyanoferrate. EDTA also avoids the precipitation of insoluble cyanides in the thermoreactor. Sulfamic acid is added to

remove nitrite (see 4.2).

6.20.2 Buffer solution for the final photometric determination (R1 in Figure A.1).

Dissolve 7,0 g of sodium hydroxide (NaOH) in 250 ml of water. Add 35,4 g of succinic acid (6.7) and dilute to

500 ml with water.
4 © ISO 2012 – All rights reserved
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SIST EN ISO 14403-1:2013
ISO 14403-1:2012(E)

The solution has a pH of approximately 4,3. When mixed with sodium hydroxide solution I (6.3; C2 in Figure A.1)

a pH of 5,2 shall be achieved.
This solution is stable for 1 week if stored in a refrigerator at 1 °C to 5 °C.
6.20.3 Chloramine-T trihydrate solution (R2 in Figure A.1).
Dissolve 0,14 g of chloramine-T (6.13) in 100 ml of water.
This solution is stable for 1 week if stored in a refrigerator at 1 °C to 5 °C.
For best results, prepare the solution daily.
6.20.4 Colour reagent (R3 in Figure A.1).

Carefully dissolve, in a 1 000 ml volumetric flask, 7,0 g of sodium hydroxide, NaOH, in about 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, adjust the solution to pH 5,2 with hydrochloric acid (6.2) or sodium hydroxide solution II (6.4).

Make up to 1 000 ml with water (6.1). Mix this solution intensively (e.g. by using a magnetic stirrer) for 1 h at

30 °C and then filter over a pleated filter (e.g. hardened ashless paper).
This solution is stable for 1 month if stored in a refrigerator at 2 °C to 5 °C.
6.21 Thiocyanate solution, calculated cyanide concentration: r = 100 mg/l.

Dissolve, in a 1 000 ml volumetric flask, 373 mg ± 1 mg of potassium thiocyanate (6.16) in sodium hydroxide

solution III (6.5), and make up to volume with sodium hydroxide solution III (6.5).

This solution is stable for 2 months if stored in an amber bottle and refrigerated at 1 °C to 5 °C.

6.22 Potassium hexacyanoferrate(III) solution, calculated cyanide concentration r = 10 mg/l.

6.22.1 Concentration, r : 1 000 mg/l.

Dissolve, in a 100 ml volumetric flask, 211 mg ± 1 mg of potassium hexacyanoferrate(III) (6.17) in sodium

hydroxide solution III (6.5), and make up to volume with sodium hydroxide solution III (6.5).

6.22.2 Concentration, r : 10 mg/l.

Make up to volume, in a 100 ml volumetric flask, 1 ml of 1 000 mg/l CN solution (6.22.1) with sodium hydroxide

solution III (6.5).

This solution is stable for 2 months if stored in a refrigerator at 1 °C to 5 °C.

7 Apparatus
Usual laboratory apparatus and in particular the following.
7.1 Flow injection analysis system for gas diffusion method.

7.1.1 General. A suitable example of the system contains the components specified in 7.1.2 to 7.1.11 (see

Figure A.1). Alternative systems are also applicable if the requirements of Clause 9 are achieved.

7.1.2 Autosampler, or other device allowing a reproducible introduction of the sample.

© ISO 2012 – All rights reserved 5
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SIST EN ISO 14403-1:2013
ISO 14403-1:2012(E)
7.1.3 Reagent reservoirs.

7.1.4 Low pulsation pump, with specific chemically inert pump tubes, for flow rates as shown in Figure A.1

as an example.
7.1.5 UV-lamp, with:
— an emission maximum >310 nm to 400 nm;
— a power of 8 W to12 W;

— a digestion coil of FEP or PTFE, internal diameter 0,8 mm, length 5 000 mm, tube wall thickness at

maximum 1 mm (e.g. 351 nm UV lamp with PTFE coil).

The equipment shall be such that no UV light with a wavelength below 290 nm can reach the sample flow to

avoid decomposition of thiocyanate to cyanide.

7.1.6 Thermoreactor 1: digestion coil of FEP with 0,8 mm × 3 600 mm, tube wall thickness at maximum

1,5 mm with a temperature of 85 °C for total cyanide and 40 °C for free cyanide (see Figure A.1).

7.1.7 Gas diffusion cell, with hydrophobic semipermeable membrane made from polypropylene or PTFE,

for example, typical thickness 90 µm to 200 µm, pore size 0,1 µm to 1 µm.

7.1.8 Manifold with highly reproducible dosing of sample and reagents, with appropriate transport systems

and connection assemblies of chemically inert polymer.

7.1.9 Photometric detector, with flow cell, wavelength 600 nm ± 10 nm. An appropriate optical pathlength

should be used to achieve a minimum absorbance (absolute value) of 0,005 for a 20 µg/l cyanide solution.

7.1.10 Recording unit (e.g. strip chart recorder, integrator, printer and plotter or a computer data system). In general,

peak height signals are measured.

7.1.11 Thermoreactor 2, 65 °C, length 3 000 mm, internal diameter 0,8 mm (see Figure A.1).

7.2 Additional apparatus.
7.2.1 Lead acetate test paper, commercially available.

7.2.2 Membrane filter assembly, with membrane filters having a pore size of 0,45 µm.

7.2.3 pH measuring device.
8 Sampling and sample preparation
Immediately after sampling, adjust the pH of the water samples to 12 wi
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