1、BRITISH STANDARD BSEN26595: 1993 BS6068-2.1: 1993 ISO6695:1982 Incorporating Amendment No.1 Water quality Determination of total arsenic Silver diethyldithiocarbamate spectrophotometric method The European Standard EN26595:1992 has the status of a British Standard UDC628.1/.3:620.1:543.42:546.19BSEN
2、 26595:1993 This British Standard, having been prepared under the directionof the Environment andPollution Standards Committee, was published underthe authority of the BoardofBSI and comes into effect on 29 April1983 BSI 10-1999 The following BSI references relate to the work on this standard: Commi
3、ttee reference EPC/44 Draft for comment80/55453DC ISBN 0 580 13235 8 Amendments issued since publication Amd. No. Date of issue Comments 7427 May 1993 Indicated by a sideline in the marginBSEN 26595:1993 BSI 10-1999 i Contents Page National foreword ii Foreword 2 Text of EN 26595 3 Publications refe
4、rred to Inside back coverBSEN 26595:1993 ii BSI 10-1999 National foreword This Section of this British Standard, which has been prepared under the direction of the Environment and Pollution Standards Committee, is identical with ISO6595:1982 “Water quality Determination of total arsenic Silver dieth
5、yldithiocarbamate spectrophotometric method”. The International Standard was prepared by subcommittee2, Physical, chemical and biochemical methods, of Technical Committee147, Water quality, of the International Organization for Standardization (ISO) as a result of discussion in which the UK particip
6、ated. In 1992 the European Committee for Standardization (CEN) accepted ISO6595:1982 as European Standard EN26595:1992. As a consequence of implementing the European Standard this British Standard is renumbered as BSEN26595 and any reference to BS6068-2.1 should be read as a reference to BSEN26595.
7、This British Standard is being published in a series of Parts subdivided into Sections that will generally correspond to particular International Standards. Sections are being, or will be, published in the following Parts. Part 0: Introduction; Part 1: Glossary; Part 2: Physical, chemical and bioche
8、mical methods; Part 3: Radiological methods; Part 4: Microbiological methods; Part 5: Biological methods; Part 6: Sampling. Terminology and conventions. The text of the International Standard has been approved as suitable for publication as a British Standard without deviation. Some terminology and
9、certain conventions are not identical with those used in British Standards; attention is drawn especially to the following. The comma has been used as a decimal marker. It is current practice in BritishStandards to use a full point on the baseline as the decimal marker. Wherever the words “Internati
10、onal Standard” appear, referring to this standard, they should be read as “British Standard”. Cross-reference. There is no British Standard identical with ISO383 to which reference is made in5.2. A related standard to ISO383 is BS572:1960 “Interchangeable conical ground glass joints”. Conical ground
11、 glass joints complying with the requirements of BS572 are interchangeable with those complying with the requirements of ISO383 but different designations are given. Additional information. The method in this Section is similar technically to the general method for the determination of arsenic given
12、 in BS4404 and in ISO2590. A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are responsible for their correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. Summary of pag
13、es This document comprises a front cover, an inside front cover, pages i and ii, theEN title page, pages2 to8, an inside back cover and a back cover. This standard has been updated (see copyright date) and may have had amendments incorporated. This will be indicated in the amendment table on the ins
14、ide front cover.EUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN26595:1992 October 1992 UDC628.1/.3:620.1:543.42:546.19 Descriptors: Water, quality, chemical analysis, determination of content, arsenic, spectrophotometric analysis, silver diethyldithiocarbamate English version Water quality Dete
15、rmination of total arsenic Silver diethyldithiocarbamate spectrophotometric method (ISO6595:1982) Qualit de leau Dosage de larsenic total Mthode spectrophotomtrique au dithyldithiocarbamate dargent (ISO6595:1982) Wasserbeschaffenheit Bestimmung von Arsen Photometrisches Verfahren mit Silberdiethyldi
16、thiocarbamat (ISO6595:1982) This European Standard was approved by CEN on1992-10-05. 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 a
17、nd bibliographical references concerning such national standards may be obtained on application to the Central Secretariat 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 responsib
18、ility of a CEN member into its own language and notified to the Central Secretariat has the same status as the official versions. CEN members are the national standards bodies of Austria, Belgium, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Po
19、rtugal, Spain, Sweden, Switzerland and United Kingdom. CEN European Committee for Standardization Comit Europen de Normalisation Europisches Komitee fr Normung Central Secretariat: rue de Stassart 36, B-1050 Brussels 1992 Copyright reserved to CEN members Ref. No. EN26595:1992 EEN26595:1992 BSI 10-1
20、999 2 Foreword This European Standard is the endorsement of ISO6595. Endorsement of ISO6595 was recommended by CEN/Technical Committee230 “Water analysis” under whose competence this European Standard will henceforth fall. This European Standard shall be given the status of a national standard, eith
21、er by publication of an identical text or by endorsement, at the latest by April1993, and conflicting national standards shall be withdrawn at the latest by April1993. The Standard was approved and in accordance with the CEN/CENELEC Internal Regulations, the following countries are bound to implemen
22、t this European Standard: Austria, Belgium, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland, UnitedKingdom. Contents Page Foreword 2 1 Scope and field of application 3 2 Definition 3 3 Principle 3 4 Reagents 3
23、5 Apparatus 4 6 Procedure 4 7 Expression of results 5 8 Test report 5 Annex Special case and interferences 7 Figure Example of reaction apparatus 6EN26595:1992 BSI 10-1999 3 The procedure specified in this International Standard is intended to be carried out by qualified chemists or by other suitabl
24、y trained and/or supervised personnel. Attention is especially drawn to the toxic nature of arsenic and its solutions and of other reagents used in this method of analysis and to the need to take particular care in the handling and disposal of solutions. Pyridine and chloroform should be handled in
25、a well-ventilated fume cupboard. Ephedrine is a scheduled drug and should be handled in accordance with appropriate regulations. 1 Scope and field of application This International Standard specifies a silver diethyldithiocarbamate spectrophotometric method for the determination of arsenic in water
26、and waste water. It is applicable for the determination of arsenic concentrations in the range from0,001 to0,1mg/l. In the case of arsenic compounds which are difficult to decompose, a method of digestion is described in the annex, clauseA.1. By appropriate dilution of the test portion with arsenic-
27、free water, higher concentrations of arsenic may also be determined. Antimony interferes with the determination (see the annex, clauseA.2). Chromium, cobalt, molybdenum, nickel, mercury, silver and platinum, in concentrations up to5mg/l, do not interfere with the determination. 2 Definition For the
28、purpose of this International Standard, the following definition applies. total arsenic the total amount of the element arsenic, in elementary form or bound in inorganic or organic compounds NOTEDepending on the redox potential and the pH of the water, arsenic may be present in the trivalent state f
29、or example as arsenite ions , in the pentavalent state for example as arsenate ions , or as organically bound arsenic. 3 Principle 3.1 Oxidation of organic compounds or sulphides by heating with potassium permanganate and potassium peroxodisulphate. 3.2 Reduction of pentavalent arsenic to the trival
30、ent state. 3.3 Reduction of the trivalent arsenic by nascent hydrogen in an acidic medium to arsenic trihydride (arsine). 3.4 Absorption of the arsine in a solution of silver diethyldithiocarbamate in either chloroform or pyridine, and spectrophotometric measurement of the red-violet complex thus fo
31、rmed, at a wavelength of510 or525nm, respectively, according to the solvent. 4 Reagents Unless otherwise specified, all reagents shall be of recognized analytical grade and the water used should be distilled or deionized water. The arsenic content of the reagents and the water should be negligibly s
32、mall. 4.1 Sulphuric acid, A =1,84g/ml. 4.2 Sulphuric acid solution, c(1/2 H 2 SO 4 ) =2mol/l. 4.3 Sodium hydroxide solution, c(NaOH) =2mol/l. Store in a polyethylene bottle. 4.4 Potassium permanganate, 50g/l solution. Dissolve50g of potassium permanganate in water and dilute to1000ml. Take care to e
33、nsure complete dissolution of the reagent. Store in a dark glass bottle. 4.5 Potassium peroxodisulphate, 40g/l solution. Dissolve40g of potassium peroxodisulphate in water and dilute to1000ml. 4.6 Hydroxylamine hydrochloride, 100g/l solution. Dissolve10g of hydroxylamine hydrochloride in water and d
34、ilute to100ml. The solution is stable for at least1 month. 4.7 Potassium iodide, 150g/l solution. Dissolve15g of potassium iodide in water and dilute to100ml. Store in a dark glass bottle. The solution is stable for at least1 month. 4.8 Tin chloride solution Dissolve55g of tin(II) chloride dihydrate
35、 in25ml of concentrated hydrochloric acid (A =1,19g/ml) and dilute to100ml with water. The solution is stable if stored in a refrigerator. 4.9 Absorption solution A Dissolve0,500g of silver diethyldithiocarbamate and0,330g of 1-ephedrine in chloroform and dilute with chloroform to200ml. This solutio
36、n is stable for at least1 month if stored in a tightly-stoppered, dark glass bottle. 4.10 Absorption solution B Dissolve1,000g of silver diethyldithiocarbamate in pyridine and dilute with pyridine to200ml. Store in a dark glass bottle. AsO 3 3 () AsO 3 4 ()EN26595:1992 4 BSI 10-1999 4.11 Zinc, coars
37、e powder, of particle size0,5 to1mm. 4.12 Copper(II) sulphate solution Dissolve15g of copper(II) sulphate pentahydrate in water and dilute to100ml. 4.13 Arsenic, standard solution corresponding to350mg of As per litre. Dissolve exactly0,462 0g of arsenic(III) oxide (As 2 O 3 ), previously dried over
38、 silica gel to constant mass, in12ml of the sodium hydroxide solution(4.3). Neutralize with the sulphuric acid solution(4.2) and dilute to1000ml with water. 1ml of this standard solution contains0,35mg of arsenic. 4.14 Arsenic, standard solution corresponding to3,5mg of As per litre. Dilute10ml of t
39、he standard arsenic solution(4.13) with water to1000ml. 1ml of this standard solution contains3,54g of arsenic. The solution is stable only for a few days. Prepare the solution just before use. 4.15 Arsenic, standard solution corresponding to0,35mg of As per litre. Dilute1ml of the standard arsenic
40、solution(4.13) with water to1000ml. 1ml of this standard solution contains0,354g of arsenic. Prepare the solution just before use. 5 Apparatus Usual laboratory equipment and 5.1 Spectrophotometer, equipped with cells of optical path length10 to50mm for optical path lengths of more than10mm, use micr
41、o-cells of small total capacity (maximum5ml). 5.2 Reaction apparatus (as shown in the figure or its equivalent), comprising a conical flask, of capacity500ml, with a ground glass joint complying with the requirements of ISO383; an absorption tube, with a ground glass joint complying with the require
42、ments of ISO383. 5.3 Volumetric flask, of capacity1000ml. 5.4 Pipettes, of capacities12510 and20ml. 5.5 Measuring cylinders, of capacities25,100 and500ml. 6 Procedure 6.1 Test portion Transfer350ml of the test sample to a measuring cylinder. If the arsenic content is expected to exceed0,1mg/l, take
43、an appropriately smaller test portion and dilute with water to350ml. 6.2 Blank test Carry out a blank test, using the same reagents in the same quantities as used in the determination and following the same procedures, including any pretreatment, but replacing the test portion by350ml of arsenic-fre
44、e water. 6.3 Choice of absorption solution The choice of absorption solution A(4.9) or B(4.10) is left to the discretion of the analyst. Pyridine has an unpleasant odour. It is, however, less volatile than chloroform, and the volume of absorption solution B is less likely to require adjustment durin
45、g the analysis. The molar absorbance coefficient when using absorption solution B is about30% greater than that when using absorption solution A. The same absorption solution shall, therefore, be used in the determination, blank test and for preparation of the calibration graphs. 6.4 Preparation of
46、calibration graphs 6.4.1 Preparation of standard matching solutions 6.4.1.1 Into each of two series of conical flasks (see5.2), pipette the volumes of the standard arsenic solutions(4.14 and4.15) shown in the following table, and make up the volume in each flask to350ml with water. Volume of standar
47、d arsenic solution(4.14) Corresponding arsenic content ml 4g/l 0 a1,0 2,0 5,0 10,0 0 10 20 50 100 Volume of standard arsenic solution(4.15) ml 0 a1,0 2,0 5,0 10,0 20,0 0 1 2 5 10 20 a Blank test of the reagents for calibration.EN26595:1992 BSI 10-1999 5 6.4.1.2 Add to each flask20ml of the sulphuric
48、 acid(4.1). 6.4.1.3 Add10ml of the potassium iodide solution(4.7) and1ml of the tin(II) chloride solution(4.8). 6.4.1.4 Transfer5ml of absorption solution A(4.9) or of absorption solution B(4.10), as appropriate (see6.3), to the absorption tube. Add1ml of the copper(II) sulphate solution(4.12) and15
49、g of the zinc(4.11) to each flask. Immediately connect the absorption tube to the flask. To ensure that the reaction apparatus is airtight, a small amount of arsenic-free grease may be applied to the ground glass joint. Allow to stand for2h to complete the evolution of arsine. Make up the volume of absorption solution to5ml to replace loss by evaporation by adding chloroform (in the case of absorption solution A) or pyridine (in the case of absorption solution B), as appropriate. Shake the flasks gently from time
