ASTM D7511-2009e1 7500 Standard Test Method for Total Cyanide by Segmented Flow Injection Analysis In-Line Ultraviolet Digestion and Amperometric Detection.pdf

1、Designation: D7511 091Standard 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.1NOTEA typographical error was editorially corrected in Section 8.13 in March 2010.1. Sc

3、ope1.1 This method is used for determining total cyanide indrinking and surface waters, 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

4、. Cyanide ions from Au(I), Co(III), Pd(II), and Ru(II)complexes are only partially determined.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 hi

5、gher concentrations bysample dilution or changing the sample loop volume.1.3 This method 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

6、units are to be regarded asstandard. No other units of measurement are included in thisstandard.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 p

7、ractices and determine the applica-bility of regulatory limitations prior to use. Specific 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 WaterD27

8、77 Practice for Determination of Precision and Bias ofApplicable Test Methods of Committee D19 on WaterD3370 Practices for Sampling Water from Closed ConduitsD3856 Guide for Good Laboratory Practices in Laborato-ries Engaged in Sampling and Analysis of WaterD4210 Practice for Intralaboratory Quality

9、 Control Proce-dures and a Discussion on Reporting Low-Level Data3D5847 Practice for Writing Quality Control Specificationsfor Standard Test Methods for Water AnalysisD6696 Guide for Understanding Cyanide SpeciesD7365 Practice for Sampling, Preservation and MitigatingInterferences in Water Samples f

10、or Analysis of Cyanide3. Terminology3.1 DefinitionsFor definitions of terms used in this testmethod, refer to Terminology D1129 and Guide D6696.3.1.1 total cyaniderefers to all cyanide-containing com-pounds in a sample, including free cyanide, WAD cyanidecompounds, and strong metal cyanide complexes

11、.4. Summary of Test Method4.1 Prior to analysis, treat the sample to remove potentialinterferences (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

12、 hydrogen cyanidegas diffuses through the membrane into an alkaline receivingsolution, where it converts 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 moni

13、tor the cyanideion. The current generated is proportional to the cyanideconcentration present in the original sample.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

14、.Current edition approved Feb. 15, 2009. Published March 2009. DOI: 10.1520/D7511-09.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary

15、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.4.2 Calibrations and data are processed with the instru-ments data

16、 acquisition software.5. Significance and Use5.1 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 was

17、tewater effluent.5.3 The method may be used for 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 interfere

18、nces can be caused by contaminants inthe reagents, 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, whi

19、ch passes through the gas diffusionmembrane and 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 produc

20、e sulfide. TA2 reagent contains asulfide scrubber 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 cya

21、nides byadding ascorbic acid, or sodium arsenite.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 Rea

22、gentModified, TA1M (see 8.21) mini-mizes interference 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 efflue

23、ntsfrom high carbonate containing wastes, such 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 th

24、rough the membrane and enter thedetector.6.8 Nitrate 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

25、200 ppm. This positive bias may beremoved by increasing 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

26、 sample separately and combine results mathemati-cally.7. Apparatus7.1 The instrument should be equipped with a precisesample introduction system, a UV digester with a 312-nm lampand TFE-efluorocarbon digestion coil, a gas diffusion manifoldwith hydrophobic membrane, and an amperometric detectionsys

27、tem to include a silver working electrode, an Ag/AgClreference 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

28、may modify the settings as long as performance of the method hasnot been degraded. Contact the instrument manufacturer for recommendedinstrument parameters.440 CFR Part 136.5The sole source of supply of the apparatus known to the committee at this timeis the trademarked CNSolution equipped with an a

29、mperometric 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 committee

30、,1which you may attend.FIG. 1 Flow Injection Analysis Apparatus 1D7511 09127.2 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 Data Acquisition SystemUse the co

31、mputer hardwareand software recommended by the instrument manufacturer tocontrol the apparatus and to collect data from the detector.7.4 Pump TubingUse tubing recommended by instrumentmanufacturer. Replace pump tubing when worn, or whenprecision is no longer acceptable.7.5 Gas Diffusion MembranesA h

32、ydrophobic membranewhich allows gaseous hydrogen cyanide 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 instrument

33、manufacturer.8. Reagents and Materials8.1 Purity of 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

34、used, provided it is first ascertained thatthe reagent 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

35、 or Type II grade of SpecificationD1193.8.3 Sodium 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

36、of NaOH in 1 L of water. Standardizewith silver nitrate 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 m

37、L of Stock Cyanide Solution (see 8.5) intoa 250 mL 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 an

38、d calculate thecyanide concentration of the Stock Cyanide 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-)

39、Pipette10.0 mL of stock cyanide solution (see 8.5) 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 1

40、0.0 mL of Intermediate Cyanide Solution 1 (see 8.6.1)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 a

41、nd 8.7.2 ranging in concentrationfrom 3 to 500 g/L 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 labora

42、tory water.8.7.2 Calibration Standards (3 and 10 g/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-mat

43、ely 5 ppm as CN-)Pipette 500 L of Stock Cyanide (see8.5) 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

44、 500 mL of laboratory water.Addglacial acetic acid (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 mu

45、st be stored in an amberglass bottle under refrigeration 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 (see6The sole source of supply of the apparatus known to the commi

46、ttee at this timeis OI Analytical Part Number A001520 and Pall Corporation Part NumberM5PU025. If you are aware of alternative suppliers, please provide this informationto ASTM International Headquarters. Your comments will receive careful consid-eration at a meeting of the responsible technical com

47、mittee,1which you may attend.7Reagent Chemicals, American Chemical Society Specifications, AmericanChemical Society, Washington, DC. For Suggestions on the testing of reagents notlisted by the American Chemical Society, see Annual Standards for LaboratoryChemicals, BDH Ltd., Poole, Dorset, U.K., and

48、 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/

49、minCycle period (total) 90 to 250 s/sampleSample load period At least enough time to completelyfill the sample loopReagent water rinse timebetween samplesAt least 15 secondsPeak Evaluation Peak height or areaWorking Potential 0.0 V vs Ag/AgClD7511 09138.3). Dilute to volume with laboratory grade water. Thesolution must be stored in an amber glass bottle underrefrigeration 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