1、BSI Standards PublicationBS ISO 17690:2015Water quality Determinationof available free cyanide(pH 6) using flow injectionanalysis (FIA), gas-diffusionand amperometric detectionBS ISO 17690:2015 BRITISH STANDARDNational forewordThis British Standard is the UK implementation of ISO 17690:2015.The UK p
2、articipation in its preparation was entrusted to Technical Committee EH/3/2, Physical chemical and biochemical methods.A list of organizations represented on this committee can be obtained on request to its secretary.This publication does not purport to include all the necessary provisions of a cont
3、ract. Users are responsible for its correct application. The British Standards Institution 2015.Published by BSI Standards Limited 2015ISBN 978 0 580 77344 0ICS 13.060.50Compliance with a British Standard cannot confer immunity from legal obligations.This British Standard was published under the aut
4、hority of the Standards Policy and Strategy Committee on 31 March 2015.Amendments/corrigenda issued since publicationDate T e x t a f f e c t e dBS ISO 17690:2015 ISO 2015Water quality Determination of available free cyanide (pH 6) using flow injection analysis (FIA), gas-diffusion and amperometric
5、detectionQualit de leau Dosage des cyanures libres disponibles (pH 6) par analyse avec injection en flux (FIA), diffusion de gaz et dtection ampromtriqueINTERNATIONAL STANDARDISO17690First edition2015-03-15Reference numberISO 17690:2015(E)BS ISO 17690:2015ISO 17690:2015(E)ii ISO 2015 All rights rese
6、rvedCOPYRIGHT PROTECTED DOCUMENT ISO 2015All rights reserved. Unless otherwise specified, 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 writte
7、n permission. Permission can be requested from either ISO at the address below or ISOs member body in the country of the requester.ISO copyright officeCase postale 56 CH-1211 Geneva 20Tel. + 41 22 749 01 11Fax + 41 22 749 09 47E-mail copyrightiso.orgWeb www.iso.orgPublished in SwitzerlandBS ISO 1769
8、0:2015ISO 17690:2015(E)Foreword ivIntroduction v1 Scope . 12 Normative references 13 Terms and definitions . 14 Interferences 24.1 Interferences by oxidizing agents . 24.2 Interferences by sulfide . 25 Principle 26 Reagents 27 Apparatus . 48 Sampling and sample preparation 59 Procedure.59.1 Flow sys
9、tem set up 59.2 Reagent blank measurement 69.3 Checking the suitability of the flow injection system 69.3.1 Electrode stabilization 69.3.2 Recovery rates 69.4 Calibration 79.5 Sample measurement 710 Calculations 711 Expression of results 812 Test report . 8Annex A (informative) Example of a flow inj
10、ection system . 9Annex B (normative) Determination of the real cyanide concentration in the potassium cyanide solution (6.5.1)10Annex C (informative) Performance data .11Bibliography .12 ISO 2015 All rights reserved iiiContents PageBS ISO 17690:2015ISO 17690:2015(E)ForewordISO (the International Org
11、anization 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 establi
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17、s document is ISO/TC 147, Water quality, Subcommittee SC 2, Physical, chemical and biochemical methods.iv ISO 2015 All rights reservedBS ISO 17690:2015ISO 17690:2015(E)IntroductionMethods using flow analysis automate wet chemical procedures and are particularly suitable for the determination of many
18、 analytes in water in large sample series at a high analysis frequency.Analyses can be performed by flow injection analysis (FIA) using the feature of an automatic dosage of the sample into a flow system (manifold) where the analytes in the sample reacts with the reagent solutions on their way throu
19、gh the manifold. The sample preparation can be integrated in the manifold. The reaction product is measured by a flow detector (e.g. amperometer). ISO 2015 All rights reserved vBS ISO 17690:2015BS ISO 17690:2015Water quality Determination of available free cyanide (pH 6) using flow injection analysi
20、s (FIA), gas-diffusion and amperometric detectionWARNING Persons using this International Standard should be familiar with the normal laboratory practice. This International Standard does not purport to address all of the safety problems, if any, associated with its use. It is the responsibility of
21、the user to establish appropriate safety and health practices and to ensure compliance with any national regulatory conditions including neutralization and proper disposal of waste solutions.IMPORTANT It is absolutely essential that tests conducted in accordance with this International Standard be c
22、arried out by suitably qualified staff.1 ScopeThis International Standard specifies methods for the determination of available free cyanide at pH 6 in various types of water (such as ground, drinking, surface, leachate, waste water, and metallurgical processing waste water) with cyanide concentratio
23、ns from 5 g/l to 500 g/l expressed as cyanide ions in the undiluted sample. The range of application can be changed by varying the operation conditions, e.g. by using a different injection volume (Figure A.1).NOTE 1 ISO 2080:2008, 3.105, the concentration of available free cyanide as determined by a
24、 specified analytical method.NOTE 2 The detection limit for this method was determined by interlaboratory testing at the national level using ASTM International D6512 Practice for Interlaboratory Quantitation Estimate.NOTE 3 Free cyanides according to ISO 14403 and ISO 17690 are not equivalent.In th
25、is method, two suitable mass concentration ranges from 5 g/l to 50 g/l and from 50 g/l to 500 g/l are described.2 Normative referencesThe following documents, in whole or in part, are normatively referenced in this document and are indispensable for its application. For dated references, only the ed
26、ition 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 methodsISO 5667-3, Water quality Sampling Part 3: Preservation and handling of water samplesISO 8466-1, W
27、ater quality Calibration and evaluation of analytical methods and estimation of performance characteristics Part 1: Statistical evaluation of the linear calibration functionISO 8466-2, Water quality Calibration and evaluation of analytical methods and estimation of performance characteristics Part 2
28、: Calibration strategy for non-linear second-order calibration functions3 Terms and definitionsFor the purposes of this document, the following terms and definitions apply.INTERNATIONAL STANDARD ISO 17690:2015(E) ISO 2015 All rights reserved 1BS ISO 17690:2015ISO 17690:2015(E)3.1available free cyani
29、de (pH 6)sum of HCN, cyanide ions, and cyanide bound in the metal-cyano complexes that are easily dissociated into HCN/CN at the pH of 6 determined in accordance with this International Standard4 Interferences4.1 Interferences by oxidizing agentsTest for the presence of oxidizing agents. Acidify KI
30、starch paper by moistening with acetate buffer (6.7.1). Add a drop of the sample to the test paper as soon as the sample is collected; a blue colour indicates the need for treatment. If oxidizing agents are present, add powdered sodium arsenite (6.9) (0,1 g/l sample) to the sample to avoid degradati
31、on of cyanide and mix well. Repeat this test until a drop of treated sample no longer produces a blue colour on the acidified KI starch test paper.4.2 Interferences by sulfideSulfide will diffuse through the gas diffusion membrane and can be detected in the amperometric flow cell. Oxidized products
32、of sulfide can also rapidly convert CN to SCN at a high pH. Test for sulfide by moistening lead acetate paper with acetate buffer solution (6.7.1) and then add a drop of sample on the lead acetate paper. If the paper turns black, sulfide is present. Add powdered lead carbonate (6.8) (0,1 g/l of samp
33、le). Repeat this test until a drop of treated sample no longer darkens the acidified lead acetate test paper. The supernatant containing cyanide shall be filtered immediately to avoid the rapid loss of cyanide due to the formation of thiocyanate.Lead acetate test strips might not be sensitive enough
34、 to detect low levels of sulfide; therefore, treatment should be performed on samples where sulfide is suspected. Interference can be confirmed by analysing the sample with or without treatment. If the measured cyanide in the untreated sample is significantly higher than in the treated sample, sulfi
35、de is likely present and treatment should be performed to remove sulfide.5 PrincipleThe sample is introduced into a carrier solution of the flow injection analysis (FIA) system through an injection valve and confluence downstream with a phosphate buffer solution at pH 6 to measure available free cya
36、nide. 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 oxidiz
37、ed at the applied potential (Eapp = 0,0 V vs. the reference electrode). The anodic current measured is proportional to the concentration of cyanide in the standard or sample injected.Calibrations and sample data are processed with the instruments data acquisition software.6 ReagentsWARNING Cyanide s
38、olutions and wastes are toxic. Waste containing these substances shall be removed appropriately.Use only reagents of recognized analytical grade.6.1 Water, grade 1, as defined 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
39、)= 1,0 mol/l.2 ISO 2015 All rights reservedBS ISO 17690:2015ISO 17690:2015(E)6.4 Sodium hydroxide solution III, c(NaOH) = 0,01 mol/l.6.5 Potassium cyanide, KCN.6.5.1 Potassium cyanide solution, KCN, (CN)= 1 000 mg/l, (see Annex B).Dissolve 2 500 mg 1 mg of potassium cyanide, KCN, in sodium hydroxide
40、 solution III (6.4) in a 1 000 ml graduated flask and make up to volume with sodium hydroxide solution III (6.4).This solution is stable for six months at (5 3) C, if stored in the dark or brown bottles.Alternatively, a potassium tetracyanozincate solution (6.6.1) can be used.6.5.2 Cyanide solution
41、I, (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.6.5.3 Calibration solutions.Prepare at least fiv
42、e and up 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).If, for example, six calibration solutions should be prepared to cover the range of 5 g/l to 50 g/l, proceed as follow
43、s.Pipette 25 ml of the cyanide solution I (6.5.2) 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, or 10 ml, respectively, of the above mentioned 0,5
44、mg/l cyanide solution and make up to volume with sodium hydroxide solution III (6.4). These solutions contain nominally 5 g/l, 15 g/l, 25 g/l, 35 g/l, 45 g/l, and 50 g/l of cyanide, respectively. Correct calibration solution concentrations based on the concentration found on titration of the potassi
45、um cyanide solution (6.5.1) following the procedure given in Annex B by multiplying the nominal value by (CN)/1 000 and round to the nearest g/l, or, for example, if six calibration solutions should be prepared to cover the range of 50 g/l to 500 g/l, proceed as follows.Pipette 25 ml of the cyanide
46、solution I (6.5.2) 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, or 10 ml, respectively, of the above mentioned 5 mg/l cyanide solution and make up to
47、 volume with sodium hydroxide solution III (6.4).These solutions contain nominally 50 g/l, 150 g/l, 250 g/l, 350 g/l, 450 g/l, and 500 g/l of cyanide, respectively. Correct calibration solution concentrations based on the concentration found on titration of the potassium cyanide solution (6.5.1) fol
48、lowing the procedure in Annex B by multiplying the nominal value by (CN)/1 000 and round to the nearest g/l.6.5.4 Electrode stabilization solution, approximately 5 mg/l as CN.Pipette 500 l of potassium cyanide solution (6.5.1) into a 100 ml volumetric flask containing 1,0 ml of sodium hydroxide solu
49、tion I (6.2). Dilute to volume with water.This solution is stable for one week if stored at (5 3) C.NOTE Lower cyanide concentrations can be used provided the detector signal is near saturation. ISO 2015 All rights reserved 3BS ISO 17690:2015ISO 17690:2015(E)6.6 Potassium tetracyanozincate, K2Zn(CN)4.6.6.1 Potassium tetracyanozincate solution, K2Zn(CN)4, (CN)= 1 000 mg/l 2 mg/l, commercially available.This solution is stable for six months at (5 3) C, if stored in the dark.6.7 R
