1、Designation: D7511 12Standard Test Method forTotal Cyanide by Segmented Flow Injection Analysis, In-LineUltraviolet Digestion and Amperometric Detection1This standard is issued under the fixed designation D7511; the number immediately following the designation indicates the year oforiginal adoption
2、or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This method is used for determining total cyanide indrinking and surface wate
3、rs, as well as domestic and industrialwastes. Cyanide ion (CN-), hydrogen cyanide in water (HC-N(aq), and the cyano-complexes of zinc, copper, cadmium,mercury, nickel, silver, and iron may be determined by thismethod. Cyanide ions from Au(I), Co(III), Pd(II), and Ru(II)complexes are only partially d
4、etermined.1.2 The method detection limit (MDL) is 1.0 g/L cyanideand the minimum level (ML) is 3 g/L. The applicable range ofthe method is 3 to 500 g/L cyanide using a 200-L sampleloop. Extend the range to analyze higher concentrations bysample dilution or changing the sample loop volume.1.3 This me
5、thod can be used by analysts experienced withequipment using segmented flow analysis (SFA) and flowinjection analysis (FIA) or working under the close supervisionof such qualified persons.1.4 The values stated in SI units are to be regarded asstandard. No other units of measurement are included in t
6、hisstandard.1.5 This standard does not purport to address all of thesafety 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. Sp
7、ecific hazardstatements are given in Note 2 and Section 9.2. Referenced Documents2.1 ASTM Standards:2D1129 Terminology Relating to WaterD1193 Specification for Reagent WaterD2036 Test Methods for Cyanides in WaterD2777 Practice for Determination of Precision and Bias ofApplicable Test Methods of Com
8、mittee D19 on WaterD3370 Practices for Sampling Water from Closed ConduitsD3856 Guide for Management Systems in LaboratoriesEngaged in Analysis of WaterD4210 Practice for Intralaboratory Quality Control Proce-dures and a Discussion on Reporting Low-Level Data3D5847 Practice for Writing Quality Contr
9、ol Specificationsfor Standard Test Methods for Water AnalysisD6696 Guide for Understanding Cyanide SpeciesD7365 Practice for Sampling, Preservation and MitigatingInterferences in Water Samples for Analysis of Cyanide3. Terminology3.1 Definitions:3.1.1 For definitions of terms used in this test metho
10、d, referto Terminology D1129 and Guide D6696.3.1.2 total cyaniderefers to all cyanide-containing com-pounds in a sample, including free cyanide, WAD cyanidecompounds, and strong metal cyanide complexes.4. Summary of Test Method4.1 Prior to analysis, treat the sample to remove potentialinterferences
11、(Sections 4 and 8). Ultraviolet (UV) digestionreleases cyanide from cyanide complexes. Acid addition con-verts cyanide ion to hydrogen cyanide gas (HCN), whichpasses under a gas diffusion membrane. The hydrogen cyanidegas diffuses through the membrane into an alkaline receivingsolution, where it con
12、verts back to cyanide ion. A silverworking electrode, silver/silver chloride reference electrode,and platinum/stainless steel counter electrode at an appliedpotential of zero volt amperometrically monitor the cyanideion. The current generated is proportional to the cyanideconcentration present in th
13、e original sample.4.2 Calibrations and data are processed with the instru-ments data acquisition software.1This test method is under the jurisdiction of ASTM Committee D19 on Waterand is the direct responsibility of Subcommittee D19.06 on Methods forAnalysis forOrganic Substances in Water.Current ed
14、ition approved Jan. 1, 2012. Published January 2012. Last previousedition published 2009 as D751109E01. DOI: 10.1520/D7511-12.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information,
15、 refer to the standards Document Summary page onthe ASTM website.3Withdrawn. The last approved version of this historical standard is referencedon www.astm.org.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.5. Significance and Use5.
16、1 Cyanide and hydrogen cyanide are highly toxic. Regu-lations have been established to require the monitoring ofcyanide in industrial and domestic wastewaters and surfacewaters.45.2 This test method is applicable for natural water, salinewaters, and wastewater effluent.5.3 The method may be used for
17、 process control in waste-water treatment facilities.5.4 The spot test outlined in Test Methods D2036, AnnexA1 can be used to detect cyanide and thiocyanate in water orwastewater, and to approximate its concentration.6. Interferences6.1 Method interferences can be caused by contaminants inthe reagen
18、ts, reagent water, glassware, etc., which may bias theresults. Take care to keep all such items free of contaminants.6.2 Sulfide and sulfide-containing compounds are positiveinterferents in this method. When acidified, sulfide formshydrogen sulfide, which passes through the gas diffusionmembrane and
19、 produces a signal at the silver electrode. Inaddition, sulfide ion reacts with cyanide ion in solution toreduce its concentration over time. Treat samples containingsulfide according to Section 11.4. During UV digestion, somesulfur compounds may produce sulfide. TA2 reagent contains asulfide scrubb
20、er that can remove up to 50 mg/L S2-from thesystem prior to amperometric detection.6.3 Treat sample containing water-soluble aldehydes, suchas formaldehyde or acetaldehyde, by adding ethylenediaminesolution.6.4 Remove oxidizing agents that decompose cyanides byadding ascorbic acid, or sodium arsenit
21、e.6.5 Thiocyanate can produce positive interference whenthey decompose to cyanide by UV irradiation or oxidation.This method uses 312 nm as the irradiation wavelength, whichkeeps thiocyanate interference from UV irradiation minimal.Use of Total Acid ReagentModified, TA1M (see 8.21) mini-mizes interf
22、erence from thiocyanate.6.6 High concentrations of carbonate can result in a nega-tive response in the amperometric detector when carbondioxide diffuses across the gas diffusion membrane into thealkaline receiving solution, reducing its pH. Treat effluentsfrom high carbonate containing wastes, such
23、as coal gasifica-tion waste and atmospheric emission scrub water, with hy-drated lime to stabilize the sample.6.7 High concentrations of surfactants interfere by changingthe characteristics of the gas diffusion membrane, allowingacid solution to pass through the membrane and enter thedetector.6.8 Ni
24、trate and nitrite if treated with sulfamic acid do notinterfere in this method.6.9 Sodium sulfite, sulfur dioxide, or sodium bisulfite do notinterfere at up to 2000 ppm SO3-.6.10 Sodium Thiosulfate exhibits a slight positive bias atconcentrations above 200 ppm. This positive bias may beremoved by in
25、creasing the amount of Bismuth Nitrate in theTA2 reagent.6.11 Samples containing particulates should be filtered priorto analysis. Extract and combine filtered extract with originalsample prior to analysis, or measure the filtered extract and theaqueous sample separately and combine results mathemat
26、i-cally.7. Apparatus7.1 The instrument should be equipped with a precisesample introduction system, a UV digester with a 312-nm lampand UV transparent digestion coil, a gas diffusion manifoldwith hydrophobic membrane, and an amperometric detectionsystem to include a silver working electrode, an Ag/A
27、gClreference electrode, and a Pt or stainless steel counter elec-trode. Examples of the apparatus schematics are shown in Fig.1. Example instrument settings are shown in Table 1.5NOTE 1The instrument settings in Table 1 are only examples. Theanalyst may modify the settings as long as performance of
28、the method hasnot been degraded. Contact the instrument manufacturer for recommendedinstrument parameters.7.2 An autosampler is recommended but not required toautomate sample injections and increase throughput. Autosamplers are usually available as an option from the instru-ments manufacturer.7.3 Da
29、ta Acquisition SystemUse the computer hardwareand software recommended by the instrument manufacturer tocontrol the apparatus and to collect data from the detector.440 CFR Part 136.5The sole source of supply of the apparatus known to the committee at this timeis the trademarked CNSolution equipped w
30、ith an amperometric flow cell, gasdiffusion, and UV digestion module, available from OI Analytical. If you are awareof alternative suppliers, please provide this information to ASTM InternationalHeadquarters. Your comments will receive careful consideration at a meeting of theresponsible technical c
31、ommittee,1which you may attend.FIG. 1 Flow Injection Analysis Apparatus 1D7511 1227.4 Pump TubingUse tubing recommended by instrumentmanufacturer. Replace pump tubing when worn, or whenprecision is no longer acceptable.7.5 Gas Diffusion MembranesA hydrophobic membranewhich allows gaseous hydrogen cy
32、anide to diffuse from thedonor to the acceptor stream at a sufficient rate to allowdetection. The gas diffusion membrane should be replacedwhen the baseline becomes noisy or every 1 to 2 weeks.67.6 Use parts and accessories as directed by instrumentmanufacturer.8. Reagents and Materials8.1 Purity of
33、 ReagentsReagent grade chemicals shall beused in all tests. Unless otherwise indicated, it is intended thatall reagents shall conform to the specifications of theAmericanChemical Society, where such specifications are available.7Other grades may be used, provided it is first ascertained thatthe reag
34、ent is of sufficiently high purity to permit its usewithout lessening the accuracy of the determination.8.2 Purity of WaterUnless otherwise indicated, referencesto water shall be understood to mean interference free reagentwater conforming to Type I or Type II grade of SpecificationD1193.8.3 Sodium
35、Hydroxide Solution (1.00 M)Dissolve 40 gNaOH in laboratory water and dilute to 1 L.8.4 Acceptor Solution (0.10 M NaOH)Dissolve 4.0 gNaOH in laboratory water and dilute to 1 L.8.5 Stock Cyanide Solution (1000 g/mL CN-)Dissolve2.51 g of KCN and 2.0 g of NaOH in 1 L of water. Standardizewith silver nit
36、rate solution as described in 8.5.1-8.5.4. Store thesolution under refrigeration and check concentration approxi-mately every 6 months and correct if necessary.8NOTE 2Warning: Because KCN is highly toxic, avoid contact orinhalation.8.5.1 Pipet 100 mL of Stock Cyanide Solution (see 8.5) intoa 250 mL
37、flask or beaker.8.5.2 Add 0.5 mL of rhodanine indicator solution (see 8.17).8.5.3 Titrate with standardized silver nitrate solution (see8.18 and 8.18.2) to the first color change from yellow tosalmon pink.8.5.4 Record the results of the titration and calculate thecyanide concentration of the Stock C
38、yanide Solution accordingto the equation in 8.18.2.8.5.5 Use the actual calculated cyanide concentration in allsubsequent calculations of working standard concentrations.8.6 Intermediate Cyanide Standards:8.6.1 Intermediate Standard 1 (100 g/mL CN-)Pipette10.0 mL of stock cyanide solution (see 8.5)
39、into a 100 mLvolumetric flask containing 1 mL of 1.0 M NaOH (see 8.3).Dilute to volume with laboratory water. Store under refrigera-tion. The standard should be stable for at least 2 weeks.8.6.2 Intermediate Cyanide Solution 2 (10 g/mL CN-)Pipette 10.0 mL of Intermediate Cyanide Solution 1 (see 8.6.
40、1)into a 100 mL volumetric flask containing 1.0 mL of 1.00 MNaOH (see 8.3). Dilute to volume with laboratory water. Thestandard should be stable for at least 2 weeks.8.7 Working Cyanide Calibration StandardsPrepare freshdaily as described in 8.7.1 and 8.7.2 ranging in concentrationfrom 3 to 500 g/L
41、CN-.8.7.1 Calibration Standards (20, 50, 100, 200, and 500 g/LCN-)Pipette 20, 50, 100, 200, and 500 L of IntermediateStandard 1 (see 8.6.1) into separate 100 mL volumetric flaskscontaining 1.0 mL of 1.00 M NaOH (see 8.3). Dilute to volumewith laboratory water.8.7.2 Calibration Standards (3 and 10 g/
42、L CN-)Pipette30 and 100 L of Intermediate Cyanide Solution 2 (see 8.6.2)into separate 100 mL volumetric flasks containing 1.0 mL of1.00 M NaOH (see 8.3). Dilute to volume with laboratorywater.8.8 Cyanide Electrode Stabilization Solution (Approxi-mately 5 ppm as CN-)Pipette 500 L of Stock Cyanide (se
43、e8.5) into a 100 mL volumetric flask containing 1.0 mL of 1.00M NaOH (see 8.3). Dilute to volume with laboratory water.The solution should be stored under refrigeration.8.9 Acetate BufferDissolve 410 g of sodium acetate tri-hydrate (NaC2H3O23H2O) in 500 mL of laboratory water.Addglacial acetic acid
44、(approximately 500 mL) to yield a pH of 4.5.8.10 Iron (II) Cyanide Stock SolutionWeigh 0.2706 gK4Fe(CN)63H2O into a 100 mL volumetric flask. Place 1.0mL of 1.00 M NaOH (see 8.3) in the flask and dilute to volumewith laboratory water. The solution must be stored in an amberglass bottle under refriger
45、ation at 4C.8.11 Iron (II) Cyanide Intermediate SolutionPipet 10.0mL of the iron (II) cyanide stock solution (see 8.10) into a 100mL volumetric flask containing 1.0 mL of 1.00 M NaOH (see8.3). Dilute to volume with laboratory grade water. Thesolution must be stored in an amber glass bottle underrefr
46、igeration at 4C.8.12 Iron (II) Cyanide Recovery SolutionPipet 100 L ofiron (II) cyanide intermediate solution (see 8.11) into a 100 mLvolumetric flask containing 1.0 mL of 1.00 M NaOH (see 8.3).Dilute to volume with laboratory water. Prepare fresh daily.8.13 Iron (III) Cyanide Stock SolutionWeigh 0.
47、2109 g ofK3Fe(CN)6in a 100 mL volumetric flask. Place 1.0 mL of 1.006The sole source of supply of the apparatus known to the committee at this timeis OI Analytical Part Number A001520 and Pall Corporation Part NumberM5PU025. If you are aware of alternative suppliers, please provide this informationt
48、o ASTM International Headquarters. Your comments will receive careful consid-eration at a meeting of the responsible technical committee,1which you may attend.7Reagent Chemicals, American Chemical Society Specifications, AmericanChemical Society, Washington, DC. For Suggestions on the testing of rea
49、gents notlisted by the American Chemical Society, see Annual Standards for LaboratoryChemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeiaand National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville,MD.8Commercially available stock cyanide solutions may be substituted.TABLE 1 Flow Injection Analysis ParametersFIA Instrument Parameter Recommended Method SettingPump Flow Rates 0.5 to 2 mL/minCycle period (total) 90 to 250 s/sampleSample load period At least enough time to completelyfill the sample loo
