1、raising standards worldwideNO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAWBSI Standards PublicationBS ISO 11262:2011Soil quality Determination of total cyanideBS ISO 11262:2011 BRITISH STANDARDNational forewordThis British Standard is the UK implementation of ISO 11262:2011. I
2、t supersedes BS ISO 11262:2003, which is withdrawn.The UK participation in its preparation was entrusted to T e c h n i c a l C o m m i t t e e E H / 4 , S o i l q u a l i t y .A list of organizations represented on this committee can be obtained on request to its secretary.This publication does not
3、 purport to include all the necessary provisions of a contract. Users are responsible for its correct application. BSI 2011 ISBN 978 0 580 66984 2 ICS 13.080.10 Compliance with a British Standard cannot confer immunity from legal obligations.This British Standard was published under the authority of
4、 the Standards Policy and Strategy Committee on 30 November 2011.Amendments issued since publicationDate T e x t a f f e c t e dBS ISO 11262:2011Soil quality Determination of total cyanideQualit du sol Dosage des cyanures totaux ISO 2011Reference numberISO 11262:2011(E)Second edition2011-11-15ISO112
5、62INTERNATIONAL STANDARDBS ISO 11262:2011 ISO 11262:2011(E)COPYRIGHT PROTECTED DOCUMENT ISO 2011All 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, with
6、out permission in writing 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 11 Fax + 41 22 749 09 47 E-mail copyrightiso.org Web www.iso.orgPublished in Switzerlandii ISO 2011 All rights r
7、eservedBS ISO 11262:2011ISO 11262:2011(E) ISO 2011 All rights reserved iiiContents PageForeword .ivIntroduction .v1 Scope 12 Normative references . 13 Terms and definitions . 14 Principle . 24.1 Direct liberation of hydrogen cyanide using orthophosphoric acid . 24.2 Determination of total cyanide co
8、ntent . 25 Reagents 25.1 Reagents for liberation and absorption of cyanide . 25.2 Reagents for the photometric determination of cyanide 35.3 Reagents for the titrimetric determination of cyanide 36 Apparatus 47 Sample preservation and preparation . 57.1 Sample preservation . 57.2 Sample preparation
9、. 58 Direct liberation using orthophosphoric acid 68.1 Procedure 68.2 Blank test . 69 Determination of cyanide Photometric method . 79.1 Applicability 79.2 Procedure 79.3 Preparation of the calibration graph 79.4 Calculation 710 Determination of cyanide Titrimetric method using an indicator . 810.1
10、Applicability 810.2 Procedure 810.3 Calculation 911 Expression of results . 912 Precision 1013 Test report .10Annex A (informative) Precision data 11Annex B (informative) Extraction with sodium hydroxide solution and subsequent liberation using orthophosphoric acid .12Annex C (informative) Compariso
11、n of the direct liberation of total cyanide and sodium hydroxide extraction with subsequent liberation .15Bibliography .16BS ISO 11262:2011ForewordISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of preparin
12、g 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 liai
13、son 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 tec
14、hnical 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 draw
15、n 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 11262 was prepared by Technical Committee ISO/TC 190, Soil quality, Subcommittee SC 3, Chemical methods and soil ch
16、aracteristics.This second edition cancels and replaces the first edition (ISO 11262:2003), which has been technically revised. This edition specifies two methods for the determination of the total cyanide content. It is only validated for direct liberation using orthophosphoric acid, Annex A provide
17、s new validation data. A method with an alkaline extraction before liberation is described in Annex B. In addition, the text has been editorially revised.ISO 11262:2011(E)iv ISO 2011 All rights reservedBS ISO 11262:2011IntroductionCyanides form simple salts with alkali earth cations and ionic comple
18、xes of varying strengths with numerous metal cations; the stability of these compounds is dependent on the cation and on the pH. Cyanide forms complexes with gold, mercury, cobalt and iron that are very stable even under mildly acidic conditions. Metal cyanide complexes also form salt-type compounds
19、 with alkali or heavy-metal cations, such as potassium ferrocyanide (K4Fe(CN)6) or copper ferrocyanide (Cu2Fe(CN)6). Cyanides can be present in soil both as cyanide ions and as complex cyanides.Determination of cyanides can be carried out under different conditions. When using mild acidic conditions
20、 (e.g. pH = 4), only so-called “easily liberatable cyanides” (also known as “weak-acid dissiciable cyanides”) are measured. Under strong acidic conditions (e.g. pH = 1), all cyanides (both easily liberatable and complex cyanides) can be determined, these are called “total cyanides”.A number of studi
21、es in soil samples have demonstrated that it is impossible to obtain reliable results for easily liberatable cyanide (ELC) using a manual ELC cyanide extraction/reflux method. Consequently, this revised International Standard does not include an ELC method.NOTE ISO 17380gives details of both an auto
22、mated ELC method and a total cyanide method.This International Standard specifies manual methods for the determination of total cyanide only. An alternative method for alkaline extraction prior to liberation using orthophosphoric acid is described in Annex B.ISO 11262:2011(E) ISO 2011 All rights res
23、erved vBS ISO 11262:2011BS ISO 11262:2011INTERNATIONAL STANDARD ISO 11262:2011(E)Soil quality Determination of total cyanideWARNING Hydrogen cyanide and its salts are toxic. Therefore, care shall be exercised when manipulating cyanide-contaminated samples. Volatile hydrogen cyanide (with a smell of
24、bitter almonds) is released from acidified solutions containing cyanide salts. As a minimum, all work shall be carried out in a fume hood and suitable plastic gloves shall be worn when handling contaminated samples.Analytical wastes containing cyanides shall be placed in a special container with a l
25、id, in the laboratory, for temporary storage. This container shall be clearly marked with labels such as “toxic waste” or “cyanides”. Periodically, the container shall be emptied and the wastes containing cyanides disposed of as “special waste” by an appropriate waste-management contractor.1 ScopeTh
26、is International Standard is applicable to as-received (field-moist) samples and specifies two different procedures for the liberation of cyanide from the soil: direct liberation of hydrogen cyanide using orthophosphoric acid (normative); extraction with sodium hydroxide solution and subsequent libe
27、ration using orthophosphoric acid (informative, see Annex B).The liberated cyanide is determined either by a photometric method or a titrimetric method using an indicator.The method is applicable to all types of soil.Under the conditions specified in this International Standard, the lower limit of a
28、pplication is 0,5 mg/kg of total cyanide (expressed on the as-received basis) for photometric determination and 10 mg/kg for titrimetric determination.NOTE Using the alkaline extraction followed by liberation using phosphoric acid, the lower limit of application is 1 mg/kg of total cyanide (expresse
29、d on the as-received basis) for photometric determination and 30 mg/kg for titrimetric determination.2 Normative referencesThe following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the late
30、st edition of the referenced document (including any amendments) applies.ISO 3696:1987, Water for analytical laboratory use Specification and test methodsISO 9297, Water quality Determination of chloride Silver nitrate titration with chromate indicator (Mohrs method)ISO 11464, Soil quality Pretreatm
31、ent of samples for physico-chemical analysisISO 11465, Soil quality Determination of dry matter and water content on a mass basis Gravimetric methodISO 14507, Soil quality Pretreatment of samples for determination of organic contaminants3 Terms and definitionsFor the purposes of this document, the f
32、ollowing terms and definitions apply. ISO 2011 All rights reserved 1BS ISO 11262:20113.1 total cyanide all compounds which form hydrogen cyanide under the conditions of this method3.2 recovery factor Frc recovery factor (Frc) of the liberation apparatus for total cyanide is the fractional recovery o
33、f a mid-range standard containing potassium hexacyanoferrate(III) carried through the whole procedure against an equivalent calibration standard of potassium cyanide not carried through the liberation stage, but only through the final detection stage of the method (mfound/mknown)4 Principle4.1 Direc
34、t liberation of hydrogen cyanide using orthophosphoric acidThe field-moist sample is homogenized and pretreated in accordance with ISO 14507, removing visible coarse constituents. It is then treated with orthophosphoric acid and the liberated hydrogen cyanide is transported by an airflow and absorbe
35、d into 1 mol/l sodium hydroxide. Tin(II) and copper(II) salts are added to suppress the interference from sulfur compounds and catalyse the decomposition of complex cyanides during the liberation process.4.2 Determination of total cyanide contentCyanide ion in the sodium hydroxide absorber solutions
36、 is determined either photometrically (see Clause 9) by a procedure based on the reaction of cyanide with chloramine-T with the formation of cyanogen chloride; this reacts with pyridine-4-carboxylic acid and 1,3-dimethylbarbituric acid to form a coloured complex, the absorbance of which is measured
37、at 606 nm, or titrimetrically (see Clause 10) by a titrimetric procedure involving titration with silver nitrate. When in excess relative to the Ag (CN)2- ion, silver ions form a red-coloured complex with the end-point indicator, 5-(4-dimethylaminobenzylidene)rhodanine.5 ReagentsAll reagents shall b
38、e of recognized analytical grade and the water used shall conform to grade 2 of ISO 3696:1987. All reagents are stable for at least 3 months unless stated otherwise.5.1 Reagents for liberation and absorption of cyanide5.1.1 Orthophosphoric acid, w(H3PO4) = 85 % (mass fraction), r = 1,69 g/ml.5.1.2 S
39、odium hydroxide solution, c(NaOH) = 1 mol/l.Dissolve 40 g of NaOH in water and dilute with water to 1 000 ml, or use commercially available solutions. Store in a polyethylene bottle.5.1.3 Hydrochloric acid solution, c(HCl) = 1 mol/l.Dilute 98,6 g of concentrated hydrochloric acid (37 %, r = 1,18 g/m
40、l) with water to 1 000 ml or use commercially available solutions.5.1.4 Tin(II) chloride solution.Dissolve 50 g of tin(II) chloride dihydrate (SnCl22H2O) in 40 ml of the hydrochloric acid solution (5.1.3) and dilute with water to 100 ml. Prepare a fresh solution daily.ISO 11262:2011(E)2 ISO 2011 All
41、 rights reservedBS ISO 11262:20115.1.5 Copper(II) sulfate solution.Dissolve 200 g of copper(II) sulfate pentahydrate (CuSO45H2O) in water and dilute with water to 1 000 ml.5.2 Reagents for the photometric determination of cyanide5.2.1 Sodium hydroxide solution, c(NaOH) = 0,8 mol/l.Dissolve 32 g of N
42、aOH in water and dilute with water to 1 000 ml. Store in a polyethylene bottle.5.2.2 Glacial acetic acid, 20 % (volume fraction).Dilute 100 ml of glacial acetic acid (r = 1,049 g/ml) to 500 ml in a measuring cylinder with water.NOTE 100 % glacial acetic acid (r = 1,049 g/ml), as well as 96 % glacial
43、 acetic acid (r = 1,06 g/ml), are commercially available.5.2.3 N-Chloro-4-methylbenzenesulfonamide sodium salt (chloramine-T) solution.Dissolve 0,5 g of chloramine-T trihydrate C7H7ClNO2SNa(3H2O) in water in a 50 ml volumetric flask and dilute to the mark. Prepare a fresh solution daily.5.2.4 Colour
44、 reagent.Dilute 7,0 g of sodium hydroxide (NaOH) in 500 ml of water. Add 16,8 g of 1,3-dimethylbarbituric acid (C6H8O3N2), and 13,6 g of pyridine-4-carboxylic acid (isonicotinic acid) (C6H5NO2), and dilute to 1 000 ml with water. Mix well for 1 h at 30 C and then filter (pore size approximately 8 m)
45、 through a pleated filter. This solution can be kept for at least 1 week, provided it is stored below 10 C in the dark, and filtered through another pleated filter (pore size approximately 8 m) before use.5.2.5 Potassium cyanide stock solution, corresponding to 100 mg/l of cyanide ion.Dissolve 250 m
46、g of potassium cyanide (KCN) in the 0,8 mol/l sodium hydroxide solution (5.2.1) and dilute with the same sodium hydroxide solution to 1 000 ml in a volumetric flask. Standardize this solution by titration with the 0,01 mol/l silver nitrate solution (5.3.1), once each day if determinations are carrie
47、d out (see Clause 9). Commercially available stock solutions may also be used. Store in the dark and at a temperature below 10 C.5.2.6 Potassium cyanide standard solution, corresponding to 10 mg/l of cyanide ion.Dilute 10 ml of stock solution (5.2.5) to 100 ml in a volumetric flask using the 0,8 mol
48、/l sodium hydroxide solution (5.2.1). Prepare daily.5.2.7 Paranitrophenol (0,1 % m/V) in ethanol.Dissolve 0,1 g of paranitrophenol in 100 ml of ethanol.5.3 Reagents for the titrimetric determination of cyanide5.3.1 Silver nitrate solution, c(AgNO3) = 0,01 mol/l.Dissolve 1,699 g of silver nitrate in
49、approximately 400 ml of water and dilute to 1 000 ml in a volumetric flask with water. Check the actual concentration of the 0,01 mol/l silver nitrate by titration with sodium chloride in accordance with ISO 9297 on a two-weekly basis. Store this solution in the dark.5.3.2 Silver nitrate solution, c(AgNO3) = 0,001 mol/l.Prepare daily from the 0,01 mol/l silver nitrate solution (5.3.1). Add 25,00 ml of 0,01 mol/l silver nitrate solution to a 250 ml volumetric flask and dilute to 250 ml with water. Cover the flask with
