ASTM D4282-2002 Standard Test Method for Determination of Free Cyanide in Water and Wastewater by Microdiffusion《用微扩散法测定水和污水中游离氰化物的标准试验方法》.pdf
《ASTM D4282-2002 Standard Test Method for Determination of Free Cyanide in Water and Wastewater by Microdiffusion《用微扩散法测定水和污水中游离氰化物的标准试验方法》.pdf》由会员分享,可在线阅读,更多相关《ASTM D4282-2002 Standard Test Method for Determination of Free Cyanide in Water and Wastewater by Microdiffusion《用微扩散法测定水和污水中游离氰化物的标准试验方法》.pdf(6页珍藏版)》请在麦多课文档分享上搜索。
1、Designation: D 4282 02Standard Test Method forDetermination of Free Cyanide in Water and Wastewater byMicrodiffusion1This standard is issued under the fixed designation D 4282; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the ye
2、ar of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method covers the determination of freecyanides in waters and wastewaters. Free cyanide is heredefine
3、d as the cyanide which diffuses as cyanide (HCN), atroom temperature, from a solution at pH 6.21.2 This test method does not include complexes that resistdissociation, such as hexacyanoferrates and gold cyanide, nordoes it include thiocyanate and cyanohydrin.1.3 This test method may be applied to wa
4、ter and wastewa-ter samples containing free cyanide from 10 to 150 g/L.Greater concentrations may be determined by appropriatedilution.1.4 This test method has been fully validated by collabora-tive testing as specified by Practice D 2777.1.5 This standard does not purport to address all of thesafet
5、y concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use. For specific hazardstatements, see 8.6, 8.9, Section 9, and 12.2.1.2. Refer
6、enced Documents2.1 ASTM Standards:D 1129 Terminology Relating to Water3D 1192 Guide for Equipment for Sampling Water andSteam in Closed Conduits3D 1193 Specification for Reagent Water3D 2777 Practice for Determination of Precision and Bias ofApplicable Test Methods of Committee D19 on Water3D 3370 P
7、ractices for Sampling Water from Closed Con-duits3D 3856 Guide for Good Laboratory Practices in Laborato-ries Engaged in Sampling and Analysis of Water3D 4210 Practice for Interlaboratory Quality Control Proce-dures and A Discussion on Reporting Low-Level Data3D 5788 Guide for Spiking Organics into
8、Aqueous Samples4D 5789 Practice for Writing Quality Control Specificationsfor Standard Test Methods for Organic Constituents4D 5847 Practice for Writing Quality Control Specificationsfor Standard Test Methods for Water Analysis4E 275 Practice for Describing and Measuring Performanceof Ultraviolet, V
9、isible, and Near-Infrared Spectrophotom-eters53. Terminology3.1 Definitions:3.1.1 For a definition of terms used in this test method referto Terminology D 1129.3.2 Definitions of Terms Specific to This Standard:3.2.1 free cyaniderefers to those simple cyanides orloosely held complexes of cyanide tha
10、t diffuse at pH 6, at roomtemperature.4. Summary of Test Method4.1 The reactions are carried out in a microdiffusion cell.4.2 The sample is treated with cadmium ion to precipitatethe hexacyanoferrates.4.3 The sample is buffered at pH 6 and allowed to stand for4h.4.4 The HCN diffuses into sodium hydr
11、oxide solution.4.5 An aliquot of the sodium hydroxide solution is treatedwith chloramine-T, and the cyanogen chloride formed isreacted with barbituric acid in pyridine. The absorbance of thecolor formed is measured using a spectrophotometer at awavelength of 580 nm.5. Significance and Use5.1 This te
12、st method is useful in distinguishing between thepotentially available free cyanide (total cyanide) and the freecyanide actually present.5.2 This test method provides a convenient technique formaking on-site free cyanide determinations.1This test method is under the jurisdiction of ASTM Committee D1
13、9 on Waterand is the direct responsibility of Subcommittee D19.06 on Methods forAnalysis forOrganic Substances in Water.Current edition approved July 10, 2002. Published August 2002. Originallypublished as D 4282 83. Last previous edition D 4282 95 (2001).2The paper by J. M. Kruse and L. E. Thibault
14、 “Determination of Free Cyanidein Ferro- and Ferricyanides,” Analytical Chemistry, 45(13): 22602261; 1973 Nov.,recommends a diffusion at pH 7. TheANSI modification (ANSI PH 4.41-1978) usespH 6. Using the conditions of the ANSI method, diffusion is completed within 4hours at pH 6. Longer diffusion ti
15、me was required at pH 7 on the samples analyzed.3Annual Book of ASTM Standards, Vol 11.01.4Annual Book of ASTM Standards, Vol 11.02.5Annual Book of ASTM Standards, Vol 03.06.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.6. Interfer
16、ences6.1 Decomposition of Hexacyanoferrates During Diffusion:6.1.1 This decomposition is virtually eliminated by allow-ing the sample to diffuse in the dark, and by precipitating thehexacyanoferrates with cadmium ion.6.2 Instability of Free Cyanide in EffluentsThe reactivityof free cyanide with such
17、 chemicals as aldehydes or oxidizingagents, is not really a method interference. However, becauseof this instability, it is important for the diffusion to begin assoon after sampling as possible. It is beyond the scope of thistest method to list all the possible cyanide reactions that may beencounte
18、red.7. Apparatus7.1 Diffusion Cell, microdiffusion cell, Conway type,68-mm outside diameter.67.2 Micropipets, 0.10 mL, 1.00 mL.7.3 Spectrophotometer, conforming to Practice E 275.7.4 Spectrophotometer Cell, 1-cm equipped with a stopper.7.5 Pipet or Syringe, adjustable (to deliver 1.30 mL).7.6 Calome
19、l Reference Electrode, with saturated KNO3electrolyte, or the equivalent.7.7 pH Meter.7.8 Silver Electrode.8. Reagents8.1 Purity of ReagentsReagent grade chemicals shall beused in all tests. Unless otherwise indicated, it is intended thatreagents shall conform to the specifications of the Committeeo
20、n Analytical Reagents of the American Chemical Society7where such specifications are available. Other grades may beused provided it is first ascertained that the reagent is ofsufficient purity to permit its use without lessening the accu-racy of the determination.8.2 Purity of WaterUnless otherwise
21、indicated, referenceto water shall be understood to mean reagent water conformingto Type II of Specification D 1193.8.3 Cadmium Chloride Solution (10 g/L), CdCl2Dissolve10.0 g of anhydrous cadmium chloride in 750 mL of water ina 1-L volumetric flask. Dilute to volume with water.8.4 Chloramine-T Reag
22、ent (10 g/L)Dissolve 1.00 g ofchloramine-T in 50 mL of water in a 100-mL volumetric flask.Dilute to volume with water. Make this reagent fresh daily.8.5 Cyanide Solution, Standard (1.00 mL = 2 g CN)Pipet 2.00 mLof cyanide stock solution (approximately 1.0 g/LCN) into a 1-L volumetric flask and dilut
23、e to volume withsodium hydroxide solution (2.05 g/L).8.6 Cyanide Solution StockDissolve 2.51 g of potassiumcyanide, KCN, in 500 mL of sodium hydroxide solution (2.05g/L) in a 1-L volumetric flask. Dilute to volume with sodiumhydroxide solution (2.05 g/L). This solution contains approxi-mately 1.0 g/
24、L cyanide (CN). (WarningKCN is highlytoxic, avoid contact or inhalation. Prepare and standardize thissolution weekly.)8.6.1 Standardizing Cyanide Stock Solution:8.6.1.1 Using a silver electrode and a reference electrode,titrate 20.0 mL of the cyanide stock solution (in a beaker alsocontaining 50 mL
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