DIN 38405-7-2002 en 8454 German standard methods for examination of water waste water and sludge - Anions (group D) - Part 7 Determination of cyanides in low polluted water by liqu.pdf

1、ICS 13.060.50Deutsche Einheitsverfahren zur Wasser-, Abwasser- und Schlammuntersuchung Anionen (Gruppe D) Teil 7: Bestimmung von Cyaniden in gering belastetem Wasser mit Ionenchromatographie oder potentio-metrischer Titration (D 7)In keeping with current practice in standards published by the Intern

2、ational Organization for Standardization(ISO), a comma has been used throughout as the decimal marker.Ref. No. DIN 38405-7 : 2002-04English price group 11 Sales No. 011110.03DEUTSCHE NORM April 200238405-7 No part of this translation may be reproduced without the prior permission ofDIN Deutsches Ins

3、titut fr Normung e.V., Berlin. Beuth Verlag GmbH, 10772 Berlin, Germany,has the exclusive right of sale for German Standards (DIN-Normen).Translation by DIN-Sprachendienst.In case of doubt, the German-language original should be consulted as the authoritative text.German standard methods for the exa

4、mination of water, waste water and sludgeAnions (group D)Determination of cyanides in lightly polluted water by ionchromatography or potentiometric titration (D 7)Continued on pages 2 to 19.All dimensions are in millimetres.ForewordThis standard has been jointly prepared by the Normenausschuss Wasse

5、rwesen (Water Practice StandardsCommittee) and Study Group Wasserchemie (Water Chemistry) of the Gesellschaft Deutscher Chemiker(German Chemists Society) (cf. Explanatory notes).Expert assistance and specialized laboratories will be required to perform the analyses specified in thisstandard. Existin

6、g safety instructions shall be observed.Depending on the objective of the analysis, a check shall be made on a case-by-case basis as to whetherand to what extent additional boundary conditions will have to be specified.ContentsPageForeword . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

7、. . . . . . . . . . . . . . . . . . . . . . . . . 1Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 Scope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 Normativ

8、e references . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 Concepts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34 Determination of total cyanide . . . . . . . . . . . . . . . . . . . . . . . . . . .

9、 . . . . . . . . 35 Determination of readily liberated cyanide . . . . . . . . . . . . . . . . . . . . . . . . . 76 Determination by ion chromatography . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87 Determination by potentiometric titration . . . . . . . . . . . . . . . . . . . . . . . .

10、 . . 108 Expression of results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 139 Test report . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1310 Results of interlaboratory testing . . . . . . . . . . . . .

11、 . . . . . . . . . . . . . . . . . . . 14Appendix A: Examples of suitable chromatographic separating systems . . 17Explanatory notes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19Bibliography . . . . . . . . . . . . . . . . . . . . . . . . . . . .

12、. . . . . . . . . . . . . . . . . . . . . . . . . 19Page 2DIN 38405-7 : 2002-04IntroductionWater may contain dissolved and/or undissolved cyanides as hydrogen cyanide, cyanide ions, cyanide com-plexes, organic compounds containing cyano groups and cyanogen chloride. The total cyanide or readilyliber

13、ated cyanide concentration is determined by ion chromatography or potentiometric titration.Refer to DIN 38405-13 when determining cyanogen chloride.CAUTION. Users of this standard should be familiar with standard laboratory practice. It is not claimedthat all the safety problems associated with the

14、use of the method have been dealt with exhaustivelyhere. It is therefore the responsibility of the user to take appropriate safety precautions and to ensurethat these comply with national regulations.1 ScopeThis standard specifies two methods of determining cyanide.The decomposition and separation m

15、ethod described in clause 4 serves to determine total cyanide in lightlypolluted water (e.g. purified waste water, ground water, drinking water and surface water) whose cyanideconcentration (calculated as cyanide ions) is between 0,01 mg/l and 10 mg/l. If the concentration is greater than10 mg/l, th

16、e sample is to be diluted or a smaller volume is to be taken.The separation method described in clause 5 serves to determine readily liberated cyanide in lightly pollutedwater (e.g. purified waste water, ground water, drinking water and surface water) whose cyanide concentration(calculated as cyanid

17、e ions) is between 0,01 mg/l and 10 mg/l. If the concentration is greater than 10 mg/l, thesample is to be diluted or a smaller volume is to be taken.The ion chromatography method described in clause 6 and the potentiometric titration method described inclause 7 are intended to measure the absorptio

18、n solutions obtained as specified in subclause 4.7 or 5.7.Cyanide concentrations less than 0,1 mg/l are to be determined with automated potentiometric titrators.2 Normative referencesThis standard incorporates, by dated or undated reference, provisions from other publications. These norma-tive refer

19、ences are cited at the appropriate places in the text, and the titles of the publications are listed below.For dated references, subsequent amendments to or revisions of any of these publications apply to thisstandard only when incorporated in it by amendment or revision. For undated references, the

20、 latest edition ofthe publication referred to applies.DIN 12242-1 Conical ground joints on laboratory glassware Dimensions and tolerancesDIN 12394 Distillation flasks for laboratory useDIN 12541-1 Straight bore stopcocks for laboratory useDIN 12596 Drechsel gas washing bottles for laboratory useDIN

21、38402-11 German standard methods for the examination of water, waste water and sludge Gen-eral information (group A) Sampling of waste water (A 11)DIN 38402-12 German standard methods for the examination of water, waste water and sludge Gen-eral information (group A) Sampling from stagnant waters (A

22、 12)DIN 38402-13 German standard methods for the examination of water, waste water and sludge Gen-eral information (group A) Sampling from aquifers (A 13)DIN 38402-14 German standard methods for the examination of water, waste water and sludge Gen-eral information (group A) Sampling of untreated wat

23、er and drinking water (A 14)DIN 38402-15 German standard methods for the examination of water, waste water and sludge Gen-eral information (group A) Sampling from flowing waters (A 15)DIN 38402-30 German standard methods for the examination of water, waste water and sludge Gen-eral information (grou

24、p A) Pretreatment, homogenization and division of non-homoge-neous water samples (A 30)DIN 38402-51 German standard methods for the examination of water, waste water and sludge Gen-eral information (group A) Calibration of analytical methods, evaluation of analyticalresults and linear calibration fu

25、nctions used to determine the performance characteristicsof analytical methods (A 51)DIN 38405-13 German standard methods for the examination of water, waste water and sludge Anions(group D) Determination of cyanides (D 13)DIN EN ISO 1042 Laboratory glassware One-mark volumetric flasks (ISO 1042 : 1

26、998)DIN EN ISO 4796-2 Laboratory glassware Bottles Part 2: Conical neck bottles (ISO 4796-2 : 2000)ISO 3696 : 1987 Water for analytical laboratory use Specification and test methodsISO 4800 : 1998 Laboratory glassware Separating funnels and dropping funnelsPage 3DIN 38405-7 : 2002-04ISO 8466-2 : 200

27、1 Water quality Calibration and evaluation of analytical methods and estimation of per-formance characteristics Part 2: Calibration strategy for non-linear second-order cali-bration functions3 Concepts3.1 Total cyanideThe concentration by mass of cyanide in simple and complex cyanides and cyano grou

28、ps in inorganic andorganic compounds that release hydrogen cyanide under the conditions of this method (e.g. cyanohydrins).NOTE 1: The concept is not understood to include simple nitriles (R-CN), such as acetonitrile and benzonitrile,or cyanate ions (OCN), thiocyanate ions (SCN) and cyanogen chlorid

29、e (ClCN), nor are these detected bythe methods described.NOTE 2: Only about 5% to 15%, depending on concentration, of cobalt cyanide complexes is decomposedby this method.3.2 Readily liberated cyanideThe concentration by mass of hydrogen cyanide in all the compounds that contain cyano groups and rel

30、easehydrogen cyanide at ambient temperature and a pH value of 4 (e.g. simple cyanides of the alkali metals andalkaline earth metals).NOTE 1: Pentacyanoferrates are only partially detected by the methods described below.NOTE 2: These compounds do not include cyanide complexes of iron and cobalt, nor

31、nitriles, cyanates, thio-cyanates and cyanogen chloride.4 Determination of total cyanide4.1 PrincipleThe cyanide compounds are decomposed at boiling point with hydrochloric acid in the presence of copper(I)ions and the hydrogen cyanide liberated is absorbed in sodium hydroxide solution.4.2 Interfere

32、nce4.2.1 Oxidizing agentsOxidizing agents (e.g. chlorine) destroy cyanide under alkaline conditions, but are removed by pretreating thesample with tin(II) chloride dihydrate as described in subclause 4.6.4.2.2 CarbonateThe lowering of the pH value of the absorption solution by carbonate concentratio

33、ns exceeding 1 000 mg/l mayresult in cyanide losses. If it is suspected that this concentration is exceeded, the sample mass used in theprocedure (see subclause 4.7) shall be reduced as appropriate.4.2.3 SulfideSulfide concentrations of 10 mg/l or greater interfere with the separation. If it is susp

34、ected that this concentra-tion is exceeded, the sample mass used in the procedure (see subclause 4.7) shall be reduced appropriately.4.3 Designation4.3.1 Designation of the method of determining total cyanide (D 7) by ion chromatography (1):Method DIN 38405 D 7-14.3.2 Designation of the method of de

35、termining total cyanide (D 7) by potentiometric titration (2):Method DIN 38405 D 7-24.4 ApparatusIn addition to standard laboratory equipment, the following shall be used.4.4.1 Equipment for decomposing and separating total cyanide, consisting of the following components(see figure 1 for set-up).4.4

36、.1.1 Washing bottles, of nominal capacity 250 ml (e.g. DIN 12596 A 250 washing bottles).4.4.1.2 Gas inlet tube.4.4.1.3 Three-neck flask, of nominal capacity 500 ml (e.g. DIN 12394 DNS 500 19 flask).Page 4DIN 38405-7 : 2002-044.4.1.4 Reflux condenser, about 300 mm long, fitted with DIN 12242-1-NS 29/

37、32 conical ground joints andsockets.4.4.1.5 Connecting tube, about 100 mm long, fitted with DIN 12242-1-NS 14/23 conical ground joints.4.4.1.6 Absorption vessel, fitted with DIN 12242-1-NS 14/32 conical ground joint (e.g. as shown in figure 2);other types of absorption vessels may be used if blowbac

38、k-proof.4.4.1.7 Dropping funnel, of nominal capacity 100 ml (e.g. dropping funnel as in ISO 4800).4.4.1.8 Air flow meter, having a measuring range of 20 l/h to 100 l/h.4.4.1.9 Suction pump, having an intake of at least 80 l/h.4.4.1.10 Heater and magnetic stirrer.4.4.1.11 pH meter and pH electrode.4.

39、4.2 Volumetric flask, of nominal capacity 100 ml (e.g. DIN EN ISO 1042 A 100 C volumetric flask).4.4.3 Flat bottom flask, preferably made of brown glass, of nominal capacity 1 000 ml (e.g. DIN EN ISO 4796-2 1000 NJ laboratory flask).Figure 1: Suggested equipment for decomposing and separating total

40、cyanideKey1 Washing bottle no. 12 Washing bottle no. 23 Gas inlet tube4 Three-neck flask5 Reflux condenser6 Connecting tube7 Absorption vessel8 Dropping funnel9 To air flow meter and suction pump10 Heater and magnetic stirrer11 DIN 12242 V 14/23 joint12 Air13 Magnetic followerPage 5DIN 38405-7 : 200

41、2-04Figure 2: Examples of absorption vessels4.5 Reagents4.5.1 GeneralAnalytical grade reagents and grade 3 water as in ISO 3696 shall be used for sample preparation. Commerciallyavailable solutions may also be used.The following reagents shall be used.4.5.2 1,12 g/ml hydrochloric acid, HCl.4.5.3 1 m

42、ol/l hydrochloric acid.4.5.4 1 mol/l sodium hydroxide solution, NaOH.4.5.5 0,4 mol/l sodium hydroxide solution.4.5.6 Tin(II) chloride solution, prepared by making up 50 g of tin(II) chloride dihydrate, SnCl2 2 H2O, and40 ml of 1 mol/l hydrochloric acid with water to 100 ml. The solution will be stab

43、le for about one week.4.5.7 Copper sulfate solution, prepared by dissolving 200 g of copper(II) sulfate pentahydrate, CuSO45 H2O, in water and making up to 1 l.4.5.8 Zinc sulfate solution, prepared by dissolving 100 g of zinc sulfate heptahydrate, ZnSO4 7 H2O, in 1 lof water.4.5.9 Potassium hexacyan

44、oferrate stock solution, having a cyanide concentration of 100 mg/l, preparedby dissolving 270,6 mg of potassium hexacyanoferrate(II) trihydrate, K4Fe(CN)6 3 H2O, in water in a 1 000 mlvolumetric flask and making up to the mark with water. If kept refrigerated at 2 C to 6 C in the dark, the solution

45、will be stable for six months.4.5.10 Standard potassium hexacyanoferrate solution, having a cyanide concentration of 10 mg/l, pre-pared by pipetting 25 ml of potassium hexacyanoferrate stock solution into a 250 ml volumetric flask andmaking up to the mark with water. If kept refrigerated at 2 C to 6

46、 C in the dark, the solution will be stable forthree months.Key1 DIN 12242 KNS 14/23 conical ground joint2 DIN 12242 V 14/23 joint3 Bulb, 16 mm in diameter, having five holes(approx. 0,5 mm in diameter)4 DIN 12541 EHB 3 straight bore stopcock5 Four holes (approx. 0,5 mm in diameter)6 DIN 12242 KNS 2

47、9/32 conical ground joint7 To washing bottle no. 2Detail XDetail XtoPage 6DIN 38405-7 : 2002-044.5.11 100 mg/l cyanide stock solution, prepared by dissolving 250,3 mg of potassium cyanide, KCN, in0,4 mol/l sodium hydroxide solution in a 1 000 ml volumetric flask and making up to the mark with 0,4 mo

48、l/lsodium hydroxide solution.Determine the cyanide concentration by mass after preparation and, should the need arise, by titrating with asilver nitrate stock solution. If kept refrigerated at 2 C to 6 C in the dark, the solution will be stable for sixmonths.4.5.12 10 mg/l standard cyanide solution,

49、 prepared by pipetting 25 ml of cyanide stock solution into a250 ml volumetric flask and making up to the mark with 0,4 mol/l sodium hydroxide solution. If kept refrigeratedat 2 C to 6 C in the dark, the solution will be stable for three months.4.5.13 0,01 mol/l silver nitrate stock solution, AgNO3, prepared by dissolving 1,698 8 g of silver nitrate inwater in a 1 000 ml volumetric flask, making up to the mark with water and storing in the dark (e.g. in a flat bottomflask made of brown gl