Water quality — Determination of total cyanide — Method using segmented flow injection, in-line ultraviolet digestion analysis by gas diffusion and amperometric detection

This document specifies operationally defined methods for the determination of total cyanide in various types of water such as drinking water, ground water, surface water, wastewaters, metallurgical processing tailings reclaim solution, heap leach barren solution, mill slurry tailings filtrate and leaching solutions, with cyanide concentrations from 5 µg/l to 2 000 mg/l expressed as cyanide ions in the undiluted sample. The range of application can be extended by reducing the sensitivity (Figure A.1.). NOTE ISO 2080:2008, 3.105, defines free cyanide. The concentration of total cyanide as defined in ISO 2080:2008, 3.191 includes free cyanide, cyanide complexed with metals in solution as cyanide anion, but not necessarily all of the metal cyanide complexes present as determined by a specified analytical method. In this method, six suitable mass concentration ranges from 5 µg/l to 50 µg/l, from 50 µg/l to 500 µg/l, from 0,5 mg/l to 5 mg/l, from 5 mg/l to 50 mg/l, from 50 mg/l to 500 mg/l and from 500 mg/l to 2 000 mg/l are described.

Qualité de l'eau — Dosage du cyanure total — Méthode utilisant l'injection en flux segmenté, l'analyse par digestion UV continue par diffusion de gaz et la détection ampérométrique

General Information

Status
Published
Publication Date
24-Sep-2020
Current Stage
6060 - International Standard published
Start Date
25-Sep-2020
Completion Date
25-Sep-2020
Ref Project

Buy Standard

Standard
ISO 22066:2020 - Water quality -- Determination of total cyanide -- Method using segmented flow injection, in-line ultraviolet digestion analysis by gas diffusion and amperometric detection
English language
15 pages
sale 15% off
Preview
sale 15% off
Preview
Draft
ISO/FDIS 22066 - Water quality -- Determination of total cyanide -- Method using segmented flow injection, in-line ultraviolet digestion analysis by gas diffusion and amperometric detection
English language
15 pages
sale 15% off
Preview
sale 15% off
Preview

Standards Content (sample)

INTERNATIONAL ISO
STANDARD 22066
First edition
2020-09
Water quality — Determination
of total cyanide — Method using
segmented flow injection, in-line
ultraviolet digestion analysis by gas
diffusion and amperometric detection
Qualité de l'eau — Dosage du cyanure total — Méthode utilisant
l'injection en flux segmenté, l'analyse par digestion UV continue par
diffusion de gaz et la détection ampérométrique
Reference number
ISO 22066:2020(E)
ISO 2020
---------------------- Page: 1 ----------------------
ISO 22066:2020(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2020

All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may

be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting

on the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address

below or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: +41 22 749 01 11
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii © ISO 2020 – All rights reserved
---------------------- Page: 2 ----------------------
ISO 22066:2020(E)
Contents Page

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

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

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

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

3 Terms and definitions ..................................................................................................................................................................................... 2

4 Principle ........................................................................................................................................................................................................................ 2

5 Interferences ............................................................................................................................................................................................................ 2

5.1 Interferences by oxidizing agents ........................................................................................................................................... 2

5.2 Interferences by sulfide ................................................................................................................................................................... 2

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

7 Apparatus ..................................................................................................................................................................................................................... 6

8 Sampling and sample preparation .................................................................................................................................................... 7

8.1 Oxidizing agent ....................................................................................................................................................................................... 7

8.2 Sulfide removal ....................................................................................................................................................................................... 7

8.3 Preservation .............................................................................................................................................................................................. 8

9 Procedure..................................................................................................................................................................................................................... 8

9.1 Flow system set up .............................................................................................................................................................................. 8

9.2 Reagent blank measurement ...................................................................................................................................................... 8

9.3 Checking the suitability of the segmented flow analysis system ................................................................. 9

9.3.1 Cyanide electrode stabilization ........................................................................................................................... 9

9.3.2 Performance verification of the system ....................................................................................................... 9

9.4 Calibration .................................................................................................................................................................................................. 9

9.5 Sample measurement .....................................................................................................................................................................10

9.5.1 Cyanide measurement..............................................................................................................................................10

10 Calculations.............................................................................................................................................................................................................10

11 Expression of results .....................................................................................................................................................................................10

12 Test report ................................................................................................................................................................................................................10

Annex A (informative) Example of a segmented flow analysis system ...........................................................................12

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

cyanide solution (6.5.1) or potassium tetracyanozincate solution (6.6.1) ...........................................13

Annex C (informative) Performance data .....................................................................................................................................................14

Bibliography .............................................................................................................................................................................................................................15

© ISO 2020 – All rights reserved iii
---------------------- Page: 3 ----------------------
ISO 22066:2020(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.

The procedures used to develop this document and those intended for its further maintenance are

described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the

different types of ISO documents should be noted. This document was drafted in accordance with the

editorial rules of the ISO/IEC Directives, Part 2 (see www .iso .org/ directives).

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. Details of

any patent rights identified during the development of the document will be in the Introduction and/or

on the ISO list of patent declarations received (see www .iso .org/ patents).

Any trade name used in this document is information given for the convenience of users and does not

constitute an endorsement.

For an explanation on the voluntary nature of standards, the meaning of ISO specific terms and

expressions related to conformity assessment, as well as information about ISO's adherence to the

World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT) see the following

URL: www .iso .org/ iso/ foreword .html.

This document was prepared by Technical Committee ISO/TC 147, Water quality, Subcommittee SC 2,

Physical, chemical and biochemical methods.

Any feedback or questions on this document should be directed to the user’s national standards body. A

complete listing of these bodies can be found at www .iso .org/ members .html.
iv © ISO 2020 – All rights reserved
---------------------- Page: 4 ----------------------
ISO 22066:2020(E)
Introduction

Methods using flow analysis automated wet chemical procedures are particularly suitable for the

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

Analyses can be performed by segmented flow injection analysis (SFIA) using the feature of an automatic

dosage of the sample into a flow system (manifold) where the analyte in the sample is digested with

ultraviolet radiation at 312 nm and the reagent solutions on its way through the manifold. The reaction

product is measured by a flow detector (for example amperometer).

Speciation of cyanide species can be inferred by comparing free cyanide in accordance with

ISO 17690:2015, available weak and dissociable cyanide in accordance with ISO 20950-1, and total

cyanide using this method.
© ISO 2020 – All rights reserved v
---------------------- Page: 5 ----------------------
INTERNATIONAL STANDARD ISO 22066:2020(E)
Water quality — Determination of total cyanide —
Method using segmented flow injection, in-line ultraviolet
digestion analysis by gas diffusion and amperometric
detection

IMPORTANT NOTE — − The performance of this method has been established for a range of

sample matrices, which are reported in ANNEX C. These matrices represent environmental,

mining influenced and metallurgical process samples. This method is therefore recommended

for mining impacted samples. Caution is recommended for the application of alternative ISO

methods to mining influenced and metallurgical process samples if those matrices are not

explicitly mentioned in the scope; as potential biases and interferences typical for them have

not been sufficiently investigated and may not be properly mitigated.

WARNING — Persons using this document should be familiar with normal laboratory practice.

This document 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 neutralization and proper disposal of waste solutions.

IMPORTANT — It is absolutely essential that tests conducted in accordance with this document

be carried out by suitably qualified staff.
1 Scope

This document specifies operationally defined methods for the determination of total cyanide in

various types of water such as drinking water, ground water, surface water, wastewaters, metallurgical

processing tailings reclaim solution, heap leach barren solution, mill slurry tailings filtrate and leaching

solutions, with cyanide concentrations from 5 µg/l to 2 000 mg/l expressed as cyanide ions in the

undiluted sample. The range of application can be extended by reducing the sensitivity (Figure A.1.).

NOTE ISO 2080:2008, 3.105, defines free cyanide. The concentration of total cyanide as defined in

ISO 2080:2008, 3.191 includes free cyanide, cyanide complexed with metals in solution as cyanide anion, but not

necessarily all of the metal cyanide complexes present as determined by a specified analytical method.

In this method, six suitable mass concentration ranges from 5 µg/l to 50 µg/l, from 50 µg/l to 500 µg/l,

from 0,5 mg/l to 5 mg/l, from 5 mg/l to 50 mg/l, from 50 mg/l to 500 mg/l and from 500 mg/l to

2 000 mg/l are described.
2 Normative references

The following documents are referred to in the text in such a way that some or all of their content

constitutes requirements 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 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
© ISO 2020 – All rights reserved 1
---------------------- Page: 6 ----------------------
ISO 22066:2020(E)
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.

ISO and IEC maintain terminological databases for use in standardization at the following addresses:

— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at http:// www .electropedia .org/
3.1
total cyanide

sum of HCN, cyanide ions and cyanide bound in the metal-cyano complexes that are dissociated, using

digestion in the presence of ultraviolet (UV) radiation at 312 nm and sulfuric acid into HCN/CN⎺ in

accordance with this document
4 Principle

In the analytical procedure employed for determination of total cyanide the sample is treated with

ultraviolet (UV) radation at 312 nm and sulfuric acid resulting in the release of bound cyanide ion

from some metal-cyano complexes. Cyanide is not totally released from the more stable gold and cobalt

cyanide complexes.

The sample is introduced into a carrier solution of the segmented flow analysis (SFA) system via a

valve and confluence downstream with a sulfuric acid solution containing sulfide removal reagent

and digested in the presence of UV radiation at 312 nm to measure total cyanide. The released

hydrogen cyanide (HCN) gas diffuses through a hydrophobic gas diffusion membrane into an alkaline

acceptor stream where the CN⎺ is captured and sent to an amperometric flow cell detector with a

silver-working electrode. In the presence of cyanide, silver electrode surface is oxidized at the applied

potential (E = 0,0 V vs. the reference electrode). The anodic current measured is proportional to the

app
concentration of cyanide in the standard or sample injected.

Calibrations and sample data are processed with the instrument's data acquisition software.

The user should be aware that the described method is operationally defined, the analytical protocol of

the standard has to be followed strictly to assure comparable results and the actual method conditions

used can affect the result obtained.
5 Interferences
5.1 Interferences by oxidizing agents

Oxidizing agents react with cyanide causing low results. The presence of oxidizing agents shall be

tested and treated, if present, just prior to pH adjustment for cyanide measurement.

5.2 Interferences by sulfide

Sulfide will diffuse through the gas diffusion membrane and can be detected in the amperometric

flow cell, causing the measurement to be biased high. Oxidized products of sulfide can also rapidly

convert CN⎺ to SCN⎺ at a high pH. A two-stage process is specified for sulfide removal. The initial lead

carbonate (6.9.4) addition treatment stage and filtration shall be carried out as soon as possible. The

sulfide removal and acidification reagent (6.8.14) is specified in this method. Its use will ensure removal

of sulfide interference up to 50 mg/l of sulfide. This shall be applied and analysis completed within 24 h

of taking the sample (see Clause 8).

NOTE In the absence of sulfide in the samples 0,1 mol/l HCl (6.2) as acidification as practiced in the original

USEPA method 1677 can also be used.
2 © ISO 2020 – All rights reserved
---------------------- Page: 7 ----------------------
ISO 22066:2020(E)
6 Reagents

WARNING — Cyanide solutions and wastes are toxic. Waste containing these substances shall

be removed appropriately. Perform work in a fume hood. Avoid contacting cyanides with acids

and aeration. Harmful if swallowed and if inhaled, very toxic to aquatic life with long lasting

effects. Handle carefully using personal protective equipment and dispose properly. Oxidation

of cyanide wastes is commonly used for cyanide waste detoxification. Calcium hypochlorite is

suitable at pH 10, using proper ventilation to capture any cyanogen chloride generated.

Use only reagents of recognized analytical grade.
6.1 Water, grade 1, as specified in ISO 3696.
6.2 Sodium hydroxide solution I, acceptor solution, c(NaOH) = 0,1 mol/l.
6.3 Sodium hydroxide solution II, c(NaOH) = 1,0 mol/l.
6.4 Sodium hydroxide solution III, c(NaOH) = 0,01 mol/l.
6.5 Potassium cyanide, KCN.
6.5.1 Potassium cyanide solution, KCN, ρ(CN) = 1 000 mg/l, (see Annex B).

Dissolve (2 503 ± 1) mg of potassium cyanide, KCN, (6.5), in sodium hydroxide solution III (6.4) in a

1 000 ml graduated flask and make up to volume with sodium hydroxide solution III (6.4). Sodium

cyanide (1 884 mg) may be substituted for potassium cyanide for stock solution preparation.

This solution is stable for six months at (5 ± 3) °C, if stored in the dark or brown bottles.

Alternatively, a potassium tetracyanozincate (2 380 mg/l) solution (6.6.1) may be used.

6.5.2 Cyanide solution I, ρ(CN) = 10 mg/l.

Pipette 1,00 ml of the potassium cyanide solution (6.5.1) in a 100 ml graduated flask and bring to

volume with sodium hydroxide solution III (6.4).

This solution is stable for one week at (5 ± 3) °C, if stored in the dark or brown bottles.

NOTE 1 Some laboratories substituted sodium cyanide for potassium cyanide for stock solution preparation

during the interlaboratory test for ISO 20950-1.
6.6 Potassium tetracyanozincate, K Zn(CN) .
2 4

6.6.1 Potassium tetracyanozincate solution, K Zn(CN) , ρ(CN) = (1 000 ± 2) mg/l, commercially

2 4
available.
This solution is stable for six months at (5 ± 3) °C, if stored in the dark.
6.6.2 Potassium tetracyanozincate solution I, ρ(CN) = 10 mg/l.

Pipette 1,00 ml of the potassium tetracyanozincate solution (6.6.1) in a 100 ml graduated flask and

bring to volume with sodium hydroxide solution III (6.4).

This solution is stable for one week at (5 ± 3) °C, if stored in the dark or brown bottles.

© ISO 2020 – All rights reserved 3
---------------------- Page: 8 ----------------------
ISO 22066:2020(E)
6.7 Calibration solutions

Prepare five to ten calibration solutions with cyanide concentrations, equidistantly distributed

over the working range, either by appropriate dilution of the cyanide solution I (6.5.2) or potassium

tetracyanozincate solution I (6.6.2).

If, for example, six calibration solutions should be prepared to cover the range of 5 µg/l to 50 µg/l,

proceed as follows:

Pipette 25 ml of the cyanide solution I (6.5.2) or potassium tetracyanozincate solution I (6.6.2), in a

500 ml graduated flask and make up to volume with sodium hydroxide solution III (6.4). This solution

contains 0,5 mg/l cyanide.

Pipette, in 100 ml graduated flasks, 1 ml, 3 ml, 5 ml, 7 ml, 9 ml, and 10 ml, respectively, of the above

mentioned 0,5 mg/l cyanide solution and make up to volume with sodium hydroxide solution III (6.4).

These solutions contain nominally 5 µg/l, 15 µg/l, 25 µg/l, 35 µg/l, 45 µg/l, and 50 µg/l of cyanide,

respectively. Correct calibration solution concentrations based the concentration found on titration of

the potassium cyanide solution (6.5.1) or potassium tetracyanozincate solution (6.6.1) used, following

the procedure given in Annex B by multiplying the nominal value by ρ(CN)/1 000 and round to the

nearest µg/l. Or, for example, if six calibration solutions should be prepared to cover the range of 50 µg/l

to 500 µg/l proceed as follows:

Pipette 25 ml of the cyanide solution I (6.5.2) or potassium tetracyanozincate solution I (6.6.2), in a

50 ml graduated flask and make up to volume with sodium hydroxide solution III (6.4). This solution

contains 5 mg/l cyanide.

Pipette, in 100 ml graduated flasks, 1 ml, 3 ml, 5 ml, 7 ml, 9 ml, and 10 ml, respectively, of the above

mentioned 5 mg/l cyanide solution and make up to volume with sodium hydroxide solution III (6.4).

These solutions contain nominally 50 µg/l, 150 µg/l, 250 µg/l, 350 µg/l, 450 µg/l, and 500 µg/l of

cyanide, respectively. Correct calibration solution concentrations based the concentration found

on titration of the potassium cyanide solution (6.5.1), following the procedure given in Annex B by

multiplying the nominal value by ρ(CN)/1 000 and round to the nearest µg/l.

Use calibration solutions less than or equal to 500 µg/l for samples with cyanide concentrations

<500 µg/l.
6.8 Reagents for the determination of total cyanide
6.8.1 Ag/AgCl reference electrode filling solution.
Fill the reference electrode as recommended by the instrument manufacturer.
6.8.2 Bismuth nitrate pentahydrate, Bi(NO ) ·5H O.
3 3 2
6.8.3 Cyanide electrode stabilization solution, approximately 5 mg/l as CN⎺.

Pipette 500 µl of potassium cyanide solution (6.5.1) or potassium tetracyanozincate solution (6.6.1),

into a 100 ml volumetric flask containing 1,0 ml of sodium hydroxide solution I (6.2). Dilute to volume

with water (6.1).
This solution is stable for one week if stored at (5 ± 3) °C.

Lower cyanide concentrations can be used, provided the detector signal is near saturation and sharp,

repeatable peaks are produced.
6.8.4 Hypophosphorous acid, H PO , 50 % solution.
3 2
4 © ISO 2020 – All rights reserved
---------------------- Page: 9 ----------------------
ISO 22066:2020(E)
6.8.5 Iron(II) cyanide stock solution, ρ(CN) = 1 000 mg/l.

Weigh 0,270 5 g K Fe(CN) ·3H O (6.8.12) into a 100 ml volumetric flask. Place 1,0 ml of 1,00 mol/l NaOH

4 6 2
(see 6.3) in the flask and dilute to volume with water (6.1).

The solution shall be stored in an amber glass bottle under refrigeration at (5 ± 3) °C

6.8.6 Iron(II) cyanide intermediate solution, ρ(CN) = 100 mg/l,

Pipette 10,0 ml of the iron(II) cyanide stock solution (6.8.5) into a 100 ml volumetric flask containing

1,0 ml of 1,00 mol/l NaOH (6.3). Dilute to volume with water (6.1).

The solution shall be stored in an amber glass bottle under refrigeration at (5 ± 3) °C.

6.8.7 Iron(II) cyanide recovery solution, ρ(CN) = 100 µg/l.

Pipette 100 μl of iron(II) cyanide intermediate solution (6.8.6) into a 100 ml volumetric flask containing

1,0 ml of 1,00 mol/l NaOH (6.3). Dilute to volume with water (6.1). Prepare fresh daily.

6.8.8 Iron(III) cyanide stock solution, ρ(CN) = 1 000 mg/l.

Weigh 0,210 9 g of K Fe(CN) (6.8.11) in a 100 ml volumetric flask. Place 1,0 ml of 1,00 mol/l NaOH (6.3)

3 6
in the flask and dilute to volume with water (6.1).

The solution shall be stored in an amber glass bottle under refrigeration at (5 ± 3) °C.

6.8.9 Iron(III) cyanide intermediate solution, ρ(CN) = 100 mg/l.

Pipette 10,0 ml of the iron(III) cyanide stock solution (6.8.8) into a 100 ml volumetric flask containing

1,0 ml of 1,00 mol/l NaOH (6.3). Dilute to volume with water (6.1).

The solution shall be stored in an amber glass bottle under refrigeration at (5 ± 3) °C.

6.8.10 Iron(III) cyanide recovery solution, ρ(CN) = 100 µg/l.

Pipette 100 μl of iron(III) cyanide intermediate solution (6.8.9) into a 100 ml volumetric flask containing

1,0 ml of 1,00 mol/l NaOH (6.3). Dilute to volume with water. Prepare fresh daily.

6.8.11 Potassium hexacyanoferrate(III), K Fe(CN)
3 6
6.8.12 Potassium hexacyanoferrate(II) trihydrate, K Fe(CN) ·3H O.
4 6 2
6.8.13 Sulfuric acid (I), ρ = 1,84 g/ml, mass fraction 95 % to 97 %.
6.8.14 Sulfide removal and acidification reagent.

Add 55 ml of water (6.1), to a 500 ml beaker, then carefully add 55 ml of concentrated sulfuric

acid (6.8.13) to the beaker. Weigh 1 g of bismuth nitrate pentahydrate, Bi(NO ) ·5H O (6.8.2) and add it

3 3 2

to the 500 ml beaker. Gently, stir the beaker until the bismuth nitrate pentahydrate has dissolved in the

acid solution. Carefully, add approximately 250 ml of water (6.1) to the beaker with stirring and allow

to cool. Then quantitatively transfer the beaker contents to a 1 l volumetric flask and fill to volume with

water (6.1).

CAUTION — This is an exothermic reaction and the solution will become hot during preparation.

© ISO 2020 – All rights reserved 5
---------------------- Page: 10 ----------------------
ISO 22066:2020(E)
6.8.15 Total acid reagent.

Carefully add 55 ml of concentrated sulfuric acid (6.8.13) to about 800 ml of water (6.1) in a 1 000 ml

volumetric flask. Cool to room temperature and add 20 ml of hypophosphorous acid (6.8.4). Dilute to

volume and mix.

WARNING — This is an exothermic reaction and the solution will become hot when preparing

this solution. Use this solution within 48 h of preparation.
6.9 Reagents for sample pre-treatment and preservation
6.9.1 Sodium acetate trihydrate, NaC H O ·3H O.
2 3 2 2
6.9.2 Acetic acid, CH COOH.
6.9.3 Acetate buffer.

Dissolve 410 g of sodium acetate trihydrate (6.9.1) in 500 ml of water (6.1). Add acetic acid (approximately

500 ml) (6.9.2) to yield a pH of 4,5.
6.9.4 Lead carbonate, PbCO , powder.
Dissolve into a concentrated solution prior to use.

DANGER — Harmful if swallowed or if inhaled, may cause cancer, may damage fertility or the

unborn child, may cause damage to organs through prolonged or repeated exposure, very toxic

to aquatic life with long lasting effects. Handle carefully using personal protective equipment

and dispose properly.
6.9.5 Lead acetate test paper, commercially available.
6.9.6 Sodium arsenite, NaAsO , powder.

DANGER — Fatal if swallowed or in contact with skin; toxic if inhaled; may cause cancer;

very toxic to aquatic life with long lasting effects. Handle carefully using personal protective

equipment and dispose properly.
6.9.6.1 Sodium arsenite solution, 5 g/l.
Dissolve 0,5 g sodium arsenate on 100 ml of water.
6.9.7 Potassium iodide starch test paper, commercially available.
7 Apparatus
7.1 Segmented flow analysis system.

A suitable example of the system is shown in Figure A.1. Alternative systems are also applicable if the

requirements in Clause 9 are achieved.

7.1.1 Autosampler or another device, allowing a reproducible introduction of the sample.

7.1.2 Reagent reservoirs.
6 © ISO 2020 – All rights reserved
---------------------- Page: 11 ----------------------
ISO 22066:2020(E)

7.1.3 Low pulsation pump, with specific chemically inert pump tubes, for flow rates as shown in

Table 1 as an example.

7.1.4 Gas diffusion cell, with hydrophobic semipermeable membrane from e.g. polypropylene or

PTFE, typical thickness 90 µm to 200 µm, pore size 0,1 µm to 1 µm, and minimum area of 150 mm in

contact with acceptor solution.

The gas diffusion membrane should be replaced when the baseline becomes noisy, or every one to

two weeks.
7.1.5 UV digester, with a 312 nm lamp and UV transparent digestion coil.

7.1.6 Manifold with highly reproducible dosing of sample and reagents, with appropriate

transport systems and connection assemblies made of chemically inert polymers.

7.1.7 Amperometric detector, with flow cell, to include a silver working electrode, a Ag/AgCl

reference electrode, and a Pt or stainless steel counter electrode.

7.1.8 Recording unit, for example strip chart recorder, integrator or printer/plotter.

As an example, instrument settings are shown in Table 1. In general, signal peak height is measured.

Use the computer hardware and software recommended by the instrument manufacturer to control

the apparatus and to collect data from the detector.
7.2 Additional apparatus, materials and measuring device.

7.2.1 Syringe membrane filter assembly, with membrane filters, pore size 0,45 µm.

7.2.2 pH meter and electrode, capable of measuring ±0,1 pH units.
8 Sampling and sample preparation
8.1 Oxidizing agent

Acidify KI starch paper (6.9.7) by moistening with acetate buffer (6.9.3). Add a drop of the sample to the

test paper as soon as the sample is collected; a blue color indicates the need for treatment. If oxidizing

agents are present, add powdered or recommended concentrated solution of sodium arsenite (6.9.6)

equivalent to 0,1 g/l sample to the sample to avoid degradation of cyanide and mix well. Repeat this

test until a drop of tr
...

FINAL
INTERNATIONAL ISO/FDIS
DRAFT
STANDARD 22066
ISO/TC 147/SC 2
Water quality — Determination
Secretariat: DIN
of total cyanide — Method using
Voting begins on:
2020­06­26 segmented flow injection, in-line
ultraviolet digestion analysis by gas
Voting terminates on:
2020­08­21
diffusion and amperometric detection
RECIPIENTS OF THIS DRAFT ARE INVITED TO
SUBMIT, WITH THEIR COMMENTS, NOTIFICATION
OF ANY RELEVANT PATENT RIGHTS OF WHICH
THEY ARE AWARE AND TO PROVIDE SUPPOR TING
DOCUMENTATION.
IN ADDITION TO THEIR EVALUATION AS
Reference number
BEING ACCEPTABLE FOR INDUSTRIAL, TECHNO­
ISO/FDIS 22066:2020(E)
LOGICAL, COMMERCIAL AND USER PURPOSES,
DRAFT INTERNATIONAL STANDARDS MAY ON
OCCASION HAVE TO BE CONSIDERED IN THE
LIGHT OF THEIR POTENTIAL TO BECOME STAN­
DARDS TO WHICH REFERENCE MAY BE MADE IN
NATIONAL REGULATIONS. ISO 2020
---------------------- Page: 1 ----------------------
ISO/FDIS 22066:2020(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2020

All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may

be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting

on the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address

below or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH­1214 Vernier, Geneva
Phone: +41 22 749 01 11
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii © ISO 2020 – All rights reserved
---------------------- Page: 2 ----------------------
ISO/FDIS 22066:2020(E)
Contents Page

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

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

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

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

3 Terms and definitions ..................................................................................................................................................................................... 2

4 Principle ........................................................................................................................................................................................................................ 2

5 Interferences ............................................................................................................................................................................................................ 2

5.1 Interferences by oxidizing agents ........................................................................................................................................... 2

5.2 Interferences by sulfide ................................................................................................................................................................... 2

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

7 Apparatus ..................................................................................................................................................................................................................... 6

8 Sampling and sample preparation .................................................................................................................................................... 7

8.1 Oxidizing agent ....................................................................................................................................................................................... 7

8.2 Sulfide removal ....................................................................................................................................................................................... 7

8.3 Preservation .............................................................................................................................................................................................. 8

9 Procedure..................................................................................................................................................................................................................... 8

9.1 Flow system set up .............................................................................................................................................................................. 8

9.2 Reagent blank measurement ...................................................................................................................................................... 8

9.3 Checking the suitability of the segmented flow analysis system ................................................................. 9

9.3.1 Cyanide electrode stabilization ........................................................................................................................... 9

9.3.2 Performance verification of the system ....................................................................................................... 9

9.4 Calibration .................................................................................................................................................................................................. 9

9.5 Sample measurement .....................................................................................................................................................................10

9.5.1 Cyanide measurement..............................................................................................................................................10

10 Calculations.............................................................................................................................................................................................................10

11 Expression of results .....................................................................................................................................................................................10

12 Test report ................................................................................................................................................................................................................10

Annex A (informative) Example of a segmented flow analysis system ...........................................................................12

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

cyanide solution (6.5.1) or potassium tetracyanozincate solution (6.6.1) ...........................................13

Annex C (informative) Performance data .....................................................................................................................................................14

Bibliography .............................................................................................................................................................................................................................15

© ISO 2020 – All rights reserved iii
---------------------- Page: 3 ----------------------
ISO/FDIS 22066:2020(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 non­governmental, 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.

The procedures used to develop this document and those intended for its further maintenance are

described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the

different types of ISO documents should be noted. This document was drafted in accordance with the

editorial rules of the ISO/IEC Directives, Part 2 (see www .iso .org/ directives).

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. Details of

any patent rights identified during the development of the document will be in the Introduction and/or

on the ISO list of patent declarations received (see www .iso .org/ patents).

Any trade name used in this document is information given for the convenience of users and does not

constitute an endorsement.

For an explanation on the voluntary nature of standards, the meaning of ISO specific terms and

expressions related to conformity assessment, as well as information about ISO's adherence to the

World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT) see the following

URL: www .iso .org/ iso/ foreword .html.

This document was prepared by Technical Committee ISO/TC 147, Water quality, Subcommittee SC 2,

Physical, chemical and biochemical methods.

Any feedback or questions on this document should be directed to the user’s national standards body. A

complete listing of these bodies can be found at www .iso .org/ members .html.
iv © ISO 2020 – All rights reserved
---------------------- Page: 4 ----------------------
ISO/FDIS 22066:2020(E)
Introduction

Methods using flow analysis automated wet chemical procedures are particularly suitable for the

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

Analyses can be performed by segmented flow injection analysis (SFIA) using the feature of an automatic

dosage of the sample into a flow system (manifold) where the analyte in the sample is digested with

ultraviolet radiation at 312 nm and the reagent solutions on its way through the manifold. The reaction

product is measured by a flow detector (for example amperometer).

Speciation of cyanide species can be inferred by comparing free cyanide in accordance with

ISO 17690:2015, available weak and dissociable cyanide in accordance with ISO 20950-1, and total

cyanide using this method.
© ISO 2020 – All rights reserved v
---------------------- Page: 5 ----------------------
FINAL DRAFT INTERNATIONAL STANDARD ISO/FDIS 22066:2020(E)
Water quality — Determination of total cyanide —
Method using segmented flow injection, in-line ultraviolet
digestion analysis by gas diffusion and amperometric
detection

IMPORTANT NOTE — − The performance of this method has been established for a range of

sample matrices, which are reported in ANNEX C. These matrices represent environmental,

mining influenced and metallurgical process samples. This method is therefore recommended

for mining impacted samples. Caution is recommended for the application of alternative ISO

methods to mining influenced and metallurgical process samples if those matrices are not

explicitly mentioned in the scope; as potential biases and interferences typical for them have

not been sufficiently investigated and may not be properly mitigated.

WARNING — Persons using this document should be familiar with normal laboratory practice.

This document 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 neutralization and proper disposal of waste solutions.

IMPORTANT — It is absolutely essential that tests conducted in accordance with this document

be carried out by suitably qualified staff.
1 Scope

This document specifies operationally defined methods for the determination of total cyanide in

various types of water such as drinking water, ground water, surface water, wastewaters, metallurgical

processing tailings reclaim solution, heap leach barren solution, mill slurry tailings filtrate and leaching

solutions, with cyanide concentrations from 5 µg/l to 2 000 mg/l expressed as cyanide ions in the

undiluted sample. The range of application can be extended by reducing the sensitivity (Figure A.1.).

NOTE ISO 2080:2008, 3.105, defines free cyanide. The concentration of total cyanide as defined in

ISO 2080:2008, 3.191 includes free cyanide, cyanide complexed with metals in solution as cyanide anion, but not

necessarily all of the metal cyanide complexes present as determined by a specified analytical method.

In this method, six suitable mass concentration ranges from 5 µg/l to 50 µg/l, from 50 µg/l to 500 µg/l,

from 0,5 mg/l to 5 mg/l, from 5 mg/l to 50 mg/l, from 50 mg/l to 500 mg/l and from 500 mg/l to

2 000 mg/l are described.
2 Normative references

The following documents are referred to in the text in such a way that some or all of their content

constitutes requirements 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 laboratory use — Specification and test methods

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

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

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

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

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

functions
© ISO 2020 – All rights reserved 1
---------------------- Page: 6 ----------------------
ISO/FDIS 22066:2020(E)
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.

ISO and IEC maintain terminological databases for use in standardization at the following addresses:

— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at http:// www .electropedia .org/
3.1
total cyanide

sum of HCN, cyanide ions and cyanide bound in the metal-cyano complexes that are dissociated, using

digestion in the presence of ultraviolet (UV) radiation at 312 nm and sulfuric acid into HCN/CN⎺ in

accordance with this document
4 Principle

In the analytical procedure employed for determination of total cyanide the sample is treated with

ultraviolet (UV) radation at 312 nm and sulfuric acid resulting in the release of bound cyanide ion

from some metal-cyano complexes. Cyanide is not totally released from the more stable gold and cobalt

cyanide complexes.

The sample is introduced into a carrier solution of the segmented flow analysis (SFA) system via a

valve and confluence downstream with a sulfuric acid solution containing sulfide removal reagent

and digested in the presence of UV radiation at 312 nm to measure total cyanide. The released

hydrogen cyanide (HCN) gas diffuses through a hydrophobic gas diffusion membrane into an alkaline

acceptor stream where the CN⎺ is captured and sent to an amperometric flow cell detector with a

silver-working electrode. In the presence of cyanide, silver electrode surface is oxidized at the applied

potential (E = 0,0 V vs. the reference electrode). The anodic current measured is proportional to the

app
concentration of cyanide in the standard or sample injected.

Calibrations and sample data are processed with the instrument's data acquisition software.

The user should be aware that the described method is operationally defined, the analytical protocol of

the standard has to be followed strictly to assure comparable results and the actual method conditions

used can affect the result obtained.
5 Interferences
5.1 Interferences by oxidizing agents

Oxidizing agents react with cyanide causing low results. The presence of oxidizing agents shall be

tested and treated, if present, just prior to pH adjustment for cyanide measurement.

5.2 Interferences by sulfide

Sulfide will diffuse through the gas diffusion membrane and can be detected in the amperometric

flow cell, causing the measurement to be biased high. Oxidized products of sulfide can also rapidly

convert CN⎺ to SCN⎺ at a high pH. A two-stage process is specified for sulfide removal. The initial lead

carbonate (6.9.4) addition treatment stage and filtration shall be carried out as soon as possible. The

sulfide removal and acidification reagent (6.8.14) is specified in this method. Its use will ensure removal

of sulfide interference up to 50 mg/l of sulfide. This shall be applied and analysis completed within 24 h

of taking the sample (see Clause 8).

NOTE In the absence of sulfide in the samples 0,1 mol/l HCl (6.2) as acidification as practiced in the original

USEPA method 1677 can also be used.
2 © ISO 2020 – All rights reserved
---------------------- Page: 7 ----------------------
ISO/FDIS 22066:2020(E)
6 Reagents

WARNING — Cyanide solutions and wastes are toxic. Waste containing these substances shall

be removed appropriately. Perform work in a fume hood. Avoid contacting cyanides with acids

and aeration. Harmful if swallowed and if inhaled, very toxic to aquatic life with long lasting

effects. Handle carefully using personal protective equipment and dispose properly. Oxidation

of cyanide wastes is commonly used for cyanide waste detoxification. Calcium hypochlorite is

suitable at pH 10, using proper ventilation to capture any cyanogen chloride generated.

Use only reagents of recognized analytical grade.
6.1 Water, grade 1, as specified in ISO 3696.
6.2 Sodium hydroxide solution I, acceptor solution, c(NaOH) = 0,1 mol/l.
6.3 Sodium hydroxide solution II, c(NaOH) = 1,0 mol/l.
6.4 Sodium hydroxide solution III, c(NaOH) = 0,01 mol/l.
6.5 Potassium cyanide, KCN.
6.5.1 Potassium cyanide solution, KCN, ρ(CN) = 1 000 mg/l, (see Annex B).

Dissolve (2 503 ± 1) mg of potassium cyanide, KCN, (6.5), in sodium hydroxide solution III (6.4) in a

1 000 ml graduated flask and make up to volume with sodium hydroxide solution III (6.4). Sodium

cyanide (1 884 mg) may be substituted for potassium cyanide for stock solution preparation.

This solution is stable for six months at (5 ± 3) °C, if stored in the dark or brown bottles.

Alternatively, a potassium tetracyanozincate (2 380 mg/l) solution (6.6.1) may be used.

6.5.2 Cyanide solution I, ρ(CN) = 10 mg/l.

Pipette 1,00 ml of the potassium cyanide solution (6.5.1) in a 100 ml graduated flask and bring to

volume with sodium hydroxide solution III (6.4).

This solution is stable for one week at (5 ± 3) °C, if stored in the dark or brown bottles.

NOTE 1 Some laboratories substituted sodium cyanide for potassium cyanide for stock solution preparation

during the interlaboratory test for ISO 20950-1.
6.6 Potassium tetracyanozincate, K Zn(CN) .
2 4

6.6.1 Potassium tetracyanozincate solution, K Zn(CN) , ρ(CN) = (1 000 ± 2) mg/l, commercially

2 4
available.
This solution is stable for six months at (5 ± 3) °C, if stored in the dark.
6.6.2 Potassium tetracyanozincate solution I, ρ(CN) = 10 mg/l.

Pipette 1,00 ml of the potassium tetracyanozincate solution (6.6.1) in a 100 ml graduated flask and

bring to volume with sodium hydroxide solution III (6.4).

This solution is stable for one week at (5 ± 3) °C, if stored in the dark or brown bottles.

© ISO 2020 – All rights reserved 3
---------------------- Page: 8 ----------------------
ISO/FDIS 22066:2020(E)
6.7 Calibration solutions

Prepare five to ten calibration solutions with cyanide concentrations, equidistantly distributed

over the working range, either by appropriate dilution of the cyanide solution I (6.5.2) or potassium

tetracyanozincate solution I (6.6.2).

If, for example, six calibration solutions should be prepared to cover the range of 5 µg/l to 50 µg/l,

proceed as follows:

Pipette 25 ml of the cyanide solution I (6.5.2) or potassium tetracyanozincate solution I (6.6.2), in a

500 ml graduated flask and make up to volume with sodium hydroxide solution III (6.4). This solution

contains 0,5 mg/l cyanide.

Pipette, in 100 ml graduated flasks, 1 ml, 3 ml, 5 ml, 7 ml, 9 ml, and 10 ml, respectively, of the above

mentioned 0,5 mg/l cyanide solution and make up to volume with sodium hydroxide solution III (6.4).

These solutions contain nominally 5 µg/l, 15 µg/l, 25 µg/l, 35 µg/l, 45 µg/l, and 50 µg/l of cyanide,

respectively. Correct calibration solution concentrations based the concentration found on titration of

the potassium cyanide solution (6.5.1) or potassium tetracyanozincate solution (6.6.1) used, following

the procedure given in Annex B by multiplying the nominal value by ρ(CN)/1 000 and round to the

nearest µg/l. Or, for example, if six calibration solutions should be prepared to cover the range of 50 µg/l

to 500 µg/l proceed as follows:

Pipette 25 ml of the cyanide solution I (6.5.2) or potassium tetracyanozincate solution I (6.6.2), in a

50 ml graduated flask and make up to volume with sodium hydroxide solution III (6.4). This solution

contains 5 mg/l cyanide.

Pipette, in 100 ml graduated flasks, 1 ml, 3 ml, 5 ml, 7 ml, 9 ml, and 10 ml, respectively, of the above

mentioned 5 mg/l cyanide solution and make up to volume with sodium hydroxide solution III (6.4).

These solutions contain nominally 50 µg/l, 150 µg/l, 250 µg/l, 350 µg/l, 450 µg/l, and 500 µg/l of

cyanide, respectively. Correct calibration solution concentrations based the concentration found

on titration of the potassium cyanide solution (6.5.1), following the procedure given in Annex B by

multiplying the nominal value by ρ(CN)/1 000 and round to the nearest µg/l.

Use calibration solutions less than or equal to 500 µg/l for samples with cyanide concentrations

<500 µg/l.
6.8 Reagents for the determination of total cyanide
6.8.1 Ag/AgCl reference electrode filling solution.
Fill the reference electrode as recommended by the instrument manufacturer.
6.8.2 Bismuth nitrate pentahydrate, Bi(NO ) ·5H O.
3 3 2
6.8.3 Cyanide electrode stabilization solution, approximately 5 mg/l as CN⎺.

Pipette 500 µl of potassium cyanide solution (6.5.1) or potassium tetracyanozincate solution (6.6.1),

into a 100 ml volumetric flask containing 1,0 ml of sodium hydroxide solution I (6.2). Dilute to volume

with water (6.1).
This solution is stable for one week if stored at (5 ± 3) °C.

Lower cyanide concentrations can be used, provided the detector signal is near saturation and sharp,

repeatable peaks are produced.
6.8.4 Hypophosphoric acid, H P O , 50 % solution.
4 2 6
4 © ISO 2020 – All rights reserved
---------------------- Page: 9 ----------------------
ISO/FDIS 22066:2020(E)
6.8.5 Iron(II) cyanide stock solution, ρ(CN) = 1 000 mg/l.

Weigh 0,270 5 g K Fe(CN) ·3H O (6.8.12) into a 100 ml volumetric flask. Place 1,0 ml of 1,00 mol/l NaOH

4 6 2
(see 6.3) in the flask and dilute to volume with water (6.1).

The solution shall be stored in an amber glass bottle under refrigeration at (5 ± 3) °C

6.8.6 Iron(II) cyanide intermediate solution, ρ(CN) = 100 mg/l,

Pipette 10,0 ml of the iron(II) cyanide stock solution (6.8.5) into a 100 ml volumetric flask containing

1,0 ml of 1,00 mol/l NaOH (6.3). Dilute to volume with water (6.1).

The solution shall be stored in an amber glass bottle under refrigeration at (5 ± 3) °C.

6.8.7 Iron(II) cyanide recovery solution, ρ(CN) = 100 µg/l.

Pipette 100 μl of iron(II) cyanide intermediate solution (6.8.6) into a 100 ml volumetric flask containing

1,0 ml of 1,00 mol/l NaOH (6.3). Dilute to volume with water (6.1). Prepare fresh daily.

6.8.8 Iron(III) cyanide stock solution, ρ(CN) = 1 000 mg/l.

Weigh 0,210 9 g of K Fe(CN) (6.8.11) in a 100 ml volumetric flask. Place 1,0 ml of 1,00 mol/l NaOH (6.3)

3 6
in the flask and dilute to volume with water (6.1).

The solution shall be stored in an amber glass bottle under refrigeration at (5 ± 3) °C.

6.8.9 Iron(III) cyanide intermediate solution, ρ(CN) = 100 mg/l.

Pipette 10,0 ml of the iron(III) cyanide stock solution (6.8.8) into a 100 ml volumetric flask containing

1,0 ml of 1,00 mol/l NaOH (6.3). Dilute to volume with water (6.1).

The solution shall be stored in an amber glass bottle under refrigeration at (5 ± 3) °C.

6.8.10 Iron(III) cyanide recovery solution, ρ(CN) = 100 µg/l.

Pipette 100 μl of iron(III) cyanide intermediate solution (6.8.9) into a 100 ml volumetric flask containing

1,0 ml of 1,00 mol/l NaOH (6.3). Dilute to volume with water. Prepare fresh daily.

6.8.11 Potassium hexacyanoferrate(III), K Fe(CN)
3 6
6.8.12 Potassium hexacyanoferrate(II) trihydrate, K Fe(CN) ·3H O.
4 6 2
6.8.13 Sulfuric acid (I), ρ = 1,84 g/ml, mass fraction 95 % to 97 %.
6.8.14 Sulfide removal and acidification reagent.

Add 55 ml of water (6.1), to a 500 ml beaker, then carefully add 55 ml of concentrated sulfuric

acid (6.8.13) to the beaker. Weigh 1 g of bismuth nitrate pentahydrate, Bi(NO ) ·5H O (6.8.2) and add it

3 3 2

to the 500 ml beaker. Gently, stir the beaker until the bismuth nitrate pentahydrate has dissolved in the

acid solution. Carefully, add approximately 250 ml of water (6.1) to the beaker with stirring and allow

to cool. Then quantitatively transfer the beaker contents to a 1 l volumetric flask and fill to volume with

water (6.1).

CAUTION — This is an exothermic reaction and the solution will become hot during preparation.

© ISO 2020 – All rights reserved 5
---------------------- Page: 10 ----------------------
ISO/FDIS 22066:2020(E)
6.8.15 Total acid reagent.

Carefully add 55 ml of concentrated sulfuric acid (6.8.13) to about 800 ml of water (6.1) in a 1 000 ml

volumetric flask. Cool to room temperature and add 20 ml of hypophosphorous acid (6.8.4). Dilute to

volume and mix.

WARNING — This is an exothermic reaction and the solution will become hot when preparing

this solution. Use this solution within 48 h of preparation.
6.9 Reagents for sample pre-treatment and preservation
6.9.1 Sodium acetate trihydrate, NaC H O ·3H O.
2 3 2 2
6.9.2 Acetic acid, CH COOH.
6.9.3 Acetate buffer.

Dissolve 410 g of sodium acetate trihydrate (6.9.1) in 500 ml of water (6.1). Add acetic acid (approximately

500 ml) (6.9.2) to yield a pH of 4,5.
6.9.4 Lead carbonate, PbCO , powder.
Dissolve into a concentrated solution prior to use.

DANGER — Harmful if swallowed or if inhaled, may cause cancer, may damage fertility or the

unborn child, may cause damage to organs through prolonged or repeated exposure, very toxic

to aquatic life with long lasting effects. Handle carefully using personal protective equipment

and dispose properly.
6.9.5 Lead acetate test paper, commercially available.
6.9.6 Sodium arsenite, NaAsO , powder.

DANGER — Fatal if swallowed or in contact with skin; toxic if inhaled; may cause cancer;

very toxic to aquatic life with long lasting effects. Handle carefully using personal protective

equipment and dispose properly.
6.9.6.1 Sodium arsenite solution, 5 g/l.
Dissolve 0,5 g sodium arsenate on 100 ml of water.
6.9.7 Potassium iodide starch test paper, commercially available.
7 Apparatus
7.1 Segmented flow analysis system.

A suitable example of the system is shown in Figure A.1. Alternative systems are also applicable if the

requirements in Clause 9 are achieved.

7.1.1 Autosampler or another device, allowing a reproducible introduction of the sample.

7.1.2 Reagent reservoirs.
6 © ISO 2020 – All rights reserved
---------------------- Page: 11 ----------------------
ISO/FDIS 22066:2020(E)

7.1.3 Low pulsation pump, with specific chemically inert pump tubes, for flow rates as shown in

Table 1 as an example.

7.1.4 Gas diffusion cell, with hydrophobic semipermeable membrane from e.g. polypropylene or

PTFE, typical thickness 90 µm to 200 µm, pore size 0,1 µm to 1 µm, and minimum area of 150 mm in

contact with acceptor solution.

The gas diffusion membrane should be replaced when the baseline becomes noisy, or every one to

two weeks.
7.1.5 UV digester, with a 312 nm lamp and UV transparent digestion coil.

7.1.6 Manifold with highly reproducible dosing of sample and reagents, with appropriate

transport systems and connection assemblies made of chemically inert polymers.

7.1.7 Amperometric detector, with flow cell, to include a silver working electrode, a Ag/AgCl

reference electrode, and a Pt or stainless steel counter electrode.

7.1.8 Recording unit, for example strip chart recorder, integrator or printer/plotter.

As an example, instrument settings are shown in Table 1. In general, signal peak height is measured.

Use the computer hardware and software recommended by the instrument manufacturer to control

the apparatus and to collect data from the detector.
7.2 Additional apparatus, materials and measuring device.

7.2.1 Syringe membrane filter assembly, with membrane filters, pore size 0,45 µm.

7.2.2 pH meter and electrode, capable of measuring ±0,1 pH units.
8 Sampling and sample preparat
...

Questions, Comments and Discussion

Ask us and Technical Secretary will try to provide an answer. You can facilitate discussion about the standard in here.