1、Designation: D 6888 04Standard Test Method forAvailable Cyanide with Ligand Displacement and FlowInjection Analysis (FIA) Utilizing Gas Diffusion Separationand Amperometric Detection1This standard is issued under the fixed designation D 6888; the number immediately following the designation indicate
2、s the year oforiginal adoption or, in the case of revision, the year 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 method is used to determine the concentr
3、ation ofavailable inorganic cyanide in an aqueous wastewater oreffluent. The method detects the cyanides that are free (HCNand CN-) and metal-cyanide complexes that are easily disso-ciated into free cyanide ions. The method does not detect theless toxic strong metal-cyanide complexes, cyanides that
4、arenot “amenable to chlorination.”1.2 Total cyanide can be determined for samples that havebeen distilled as described in Test Methods D 2036, TestMethod A, Total Cyanides after Distillation. The cyanidecomplexes are dissociated and absorbed into the sodiumhydroxide capture solution, which can be an
5、alyzed with thistest method; therefore, ligand exchange reagents from sections8.12 and 8.13 would not be required when determining totalcyanide after distillation.1.3 This procedure is applicable over a range of approxi-mately 2 to 400 g/L (parts per billion) available cyanide.Higher concentrations
6、can be analyzed by dilution or lowerinjection volume.1.4 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 o
7、f regulatory limitations prior to use. Specific hazardstatements are given in Note 2 and Section 9.2. Referenced Documents2.1 ASTM Standards:2D 1129 Terminology Relating to WaterD 1193 Specification for Reagent WaterD 2036 Test Methods for Cyanides in WaterD 2777 Practice for Determination of Precis
8、ion and Bias ofApplicable Methods of Committee D19 on WaterD 3370 Practices for Sampling Water from Closed ConduitsD 3856 Guide for Good Laboratory Practices in Laborato-ries Engaged in Sampling and Analysis of WaterD 4210 Practice for Intralaboratory Quality Control Proce-dures and a Discussion on
9、Reporting Low-Level Data3D 4375 Practice for Basic Statistics in Committee D19 onWaterD 5847 Practice for Writing Quality Control Specificationsfor Standard Test Methods for Water AnalysisD 6696 Guide for Understanding Cyanide SpeciesE 60 Practice for Analysis of Metals, Ores, and RelatedMaterials b
10、y Molecular Absorption SpectrometryE 275 Practice for Describing and Measuring Performanceof Ultraviolet, Visible, and Near Infrared Spectrophotom-etersE 1601 Practice for Conducting an Interlaboratory Study toEvaluate the Performance of an Analytical Method3. Terminology3.1 DefinitionsFor definitio
11、ns of terms used in this testmethod, refer to Terminology D 1129 and Guide D 6696.3.2 available cyanideInorganic cyanides that are free(HCN and CN-) and metal-cyanide complexes that are easilydissociated into free cyanide ions. Available cyanide does notinclude the less toxic strong metal-cyanide co
12、mplexes, cya-nides that are not “amenable to chlorination.”4. Summary of Test Method4.1 Complex cyanides bound with nickel or mercury arereleased by ligand displacement by the addition of a liganddisplacement agent prior to analysis.4.2 Other weak and dissociable cyanide species do notrequire ligand
13、 displacement.4.3 The treated sample is introduced into a flow injectionanalysis (FIA) system where it is acidified to form hydrogencyanide (HCN). The hydrogen cyanide gas diffuses through ahydrophobic gas diffusion membrane, from the acidic donorstream into an alkaline acceptor stream.1This test me
14、thod 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 edition approved June 1, 2004. Published June 2004. Originallyapproved in 2003. Last previous addition approved in 2003 a
15、s D 6888 03.2For 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 page onthe ASTM website.3Withdrawn.1Copyright ASTM International, 100 Bar
16、r Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.4.4 The captured cyanide is sent to an amperometric flow-cell detector with a silver-working electrode. In the presence ofcyanide, silver in the working electrode is oxidized at theapplied potential. The anodic current meas
17、ured is proportionalto the concentration of cyanide in the standard or sampleinjected.4.5 Calibrations and data are processed with the instru-ments data acquisition software.5. Significance and Use5.1 Cyanide and hydrogen cyanide are highly toxic. Regu-lations have been established to require the mo
18、nitoring ofcyanide in industrial and domestic wastes and surface waters.45.2 This test method is applicable for natural water, salinewaters, and wastewater 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 D 2036, A
19、nnexA1 can be used to detect cyanide and thiocyanate in water orwastewater, and to approximate its concentration.6. Interferences6.1 High levels of carbonate can release CO2into theacceptor stream and cause an interference with the amperomet-ric detector that result in a slight masking effect (15 %
20、negativebias with 20 ppb cyanide in 1500 ppm carbonate). Refer to 11.1for sample pretreatment.6.2 Sulfide will diffuse through the gas diffusion membraneand can be detected in the amperometric flowcell. Oxidizedproducts of sulfide can also rapidly convert CN-to SCN-at ahigh pH. Refer to 11.3 for sul
21、fide removal.6.3 Refer to section 6.1 of Test Methods D 2036 foradditional information regarding interferences for the analysisof cyanide and Section 11 of Test Methods D 2036 forelimination of interferences.7. Apparatus7.1 The instrument should be equipped with a precisesample introduction system,
22、a gas diffusion manifold withhydrophobic membrane, and an amperometric detection sys-tem to include a silver working electrode, a Ag/AgCl referenceelectrode, and a Pt or stainless steel counter electrode. Ex-amples of the apparatus schematics are shown in Figs. 1 and 2.Example instrument settings ar
23、e shown in Table 1.5NOTE 1The instrument settings in Table 1 are only examples. Theanalyst may modify the settings as long as performance of the method hasnot been degraded. Contact the instrument manufacturer for recommendedinstrument parameters.7.2 An autosampler is recommended but not required to
24、automate sample injections and increase throughput. Autosam-plers are usually available as an option from the instrumentsmanufacturer.7.3 Data Acquisition SystemUse the computer hardwareand software recommended by the instrument manufacturer tocontrol the apparatus and to collect data from the detec
25、tor.7.4 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 cyanide to diffuse from the440 CFR Part 136.5Both theALPKEM CN Solution 3000 equ
26、ipped with an amperometric flowcell,Available from O.I. Analytical, and Lachat Instruments QuikChem Automated IonAnalyzer using Method 10-204-00-5-A have been found to be suitable for thisanalysis.FIG. 1 Flow Injection Analysis Apparatus 1D6888042donor to the acceptor stream at a sufficient rate to
27、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 ReagentsReagent grade chemicals shall beused in all tests. Unless otherwise i
28、ndicated, 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 reagent is of sufficiently high purity to permit its usewithout lessening the accu
29、racy of the determination.8.2 Purity of WaterUnless otherwise indicated, referencesto water shall be understood to mean reagent water conformingto Type II grade of Specification D 1193.8.3 Sodium Hydroxide Solution (1.00 M)Dissolve 40 gNaOH in laboratory water and dilute to 1 L.8.4 Acceptor Solution
30、 A (0.10 M NaOH)Dissolve 4.0 gNaOH in laboratory water and dilute to 1 L.8.5 Acceptor Solution B, Carrier B (0.025 M NaOH)Dissolve 1.0 g NaOH in laboratory water and dilute to 1 L.8.6 Stock Cyanide Solution (1000 g/mL CN-)Dissolve2.51 g of KCN and 2.0 g of NaOH in 1 L of water. Standardizewith silve
31、r nitrate solution as described in Test MethodsD 2036, section 16.2. Store the solution under refrigeration andcheck concentration approximately every 6 months and correctif necessary.8NOTE 2Warning: Because KCN is highly toxic, avoid contact orinhalation.8.7 Intermediate Cyanide Standards:8.7.1 Int
32、ermediate Standard 1 (100 g/mL CN-)Pipette10.0 mL of stock cyanide solution (see 8.6) 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.8.7.2 Intermediate Cyanid
33、e Solution 2 (10 g/mL CN-)Pipette 10.0 mL of Intermediate Cyanide Solution 1 (see 8.7.1)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.8.8 Working Cyanide Calibration StandardsPrepare
34、 freshdaily as described in 8.8.1 and 8.8.2 ranging in concentrationfrom 2 to 400 g/L CN-.8.8.1 Calibration Standards (20, 50, 100, 200, and 400 g/LCN-)Pipette 20, 50, 100, 200, and 400 L of IntermediateStandard 1 (see 8.7.1) into separate 100 mL volumetric flasks6Gelmen Sciences Part Number M5PU025
35、, ALPKEM Part Number A0015200,and Lachat Instruments Part Number 50398 have found to be suitable for thisanalysis.7Reagent Chemicals, American Chemical Society Specifications , Am. ChemicalSoc., Washington, DC. For suggestions on the testing of reagents not listed by theAmerican chemical Society, se
36、e Analar Standards for Laboratory Chemicals, BDHLtd., Poole, Dorset, U.K., and the United States Pharmacopeia.8Commerical Solutions of Stock Cyanide may be substituted.FIG. 2 Flow Injection Analysis Apparatus 2TABLE 1 Flow Injection Analysis ParametersFIA InstrumentParameterRecommendedMethod Setting
37、Pump 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 loopReagent water rinse timebetween samplesAt least 15 secondsPeak Evaluation Peak height or areaWorking Potential 0.0 V vs Ag/AgClD6888043containing 1.0 mL of 1
38、.00 M NaOH (see 8.3). Dilute to volumewith laboratory water.8.8.2 Calibration Standards (2 and 10 g/L CN-)Pipette20 and 100 L of Intermediate Cyanide Solution 2 (see 8.7.2)into separate 100 mL volumetric flasks containing 1.0 mL of1.00 M NaOH (see 8.3). Dilute to volume with laboratorywater.8.9 Cyan
39、ide Electrode Stabilization Solution (Approxi-mately 5 ppm as CN-)Pipette 500 L of Stock Cyanide (see8.6) 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.8.10 Acetate BufferDissolve 410
40、 g of sodium acetatetrihydrate (NaC2H3O23H2O) in 500 mL of laboratory water.Add glacial acetic acid (approximately 500 mL) to yield a pHof 4.5.8.11 Carrier A and Acidification Reagent (0.12 M HCl)Transfer 10 mL of Trace Metal Grade concentrated hydrochlo-ric acid intoa1Lvolumetric flask. Carefully,
41、dilute to volumewith laboratory water.8.12 Ligand Exchange Reagent 1 (TEP Solution)Weigh0.10 g tetraethylenepentamine (TEP) into a 100 mL volumetricflask. Dilute to volume with laboratory water. The solutionshould be stored at room temperature.8.13 Ligand Exchange Reagent 2 (Dithizone Solution)Weigh
42、 0.010 g of dithizone into a 100 mL volumetric flaskcontaining 1.0 mL of 1.00 M NaOH (see 8.3). Dilute to volumewith laboratory water. Sonicate if necessary until all of thedithizone has dissolved. The solution should be stored at roomtemperature.NOTE 3Commercially prepared or alternative ligand exc
43、hange re-agents can be used if equivalent results can be demonstrated. Commercialreagents should be used in accordance with manufacturers instructions.98.14 Mercury (II) Cyanide Stock SolutionWeigh 0.4854 gHg(CN)2into a 100 mL volumetric flask. Place 1.0 mL of 1.00M NaOH (see 8.3) in the flask and d
44、ilute to volume withlaboratory water. Hg(CN)2as CN-= 1000 mg/L. The solutionmust be stored in an amber glass bottle under refrigeration at4C.8.15 Mercury (II) Cyanide Intermediate SolutionPipet10.0 mL of the mercury (II) cyanide stock solution (see 8.14)into a 100 mL volumetric flask containing 1.0
45、mL of 1.00 MNaOH (see 8.3). Dilute to volume with laboratory grade water.Hg(CN)2as CN-= 100 mg/L. The solution must be stored in anamber glass bottle under refrigeration at 4C.8.16 Mercury (II) Cyanide Recovery SolutionPipet 100L of mercury II cyanide intermediate solution (see 8.15) intoa 100 mL vo
46、lumetric flask containing 1.0 mL of 1.00 M NaOH(see 8.3). Dilute to volume with laboratory water. Hg(CN)2asCN-= 100 g/L. Prepare fresh daily.8.17 Potassium Nickel Cyanide Stock SolutionWeigh0.2488 g of K2Ni(CN)4H2O in a 100 mL volumetric flask.Place 1.0 mL of 1.00 M NaOH (see 8.3) in the flask and d
47、iluteto volume with laboratory water. K2Ni(CN)4as CN-= 1000mg/L. The solution must be stored in an amber glass bottleunder refrigeration at 4C.8.18 Potassium Nickel Cyanide Intermediate SolutionPipet 10.0 mL of the potassium nickel cyanide stock solution(see 8.17) into a 100 mL volumetric flask cont
48、aining 1.0 mL of1.00 M NaOH (see 8.3). Dilute to volume with laboratorygrade water. K2Ni(CN)4as CN-= 100 mg/L. The solution mustbe stored in an amber glass bottle under refrigeration at 4C.8.19 Potassium Nickel Cyanide Recovery SolutionPipet100 L of potassium nickel cyanide intermediate solution (se
49、e8.18) into a 100 mL volumetric flask containing 1.0 mL of 1.00M NaOH (see 8.3). Dilute to volume with laboratory water.K2Ni(CN)4as CN-= 100 g/L. Prepare fresh daily.8.20 Ag/AgCl Reference Electrode Filling SolutionFillthe reference electrode as recommended by the instrumentmanufacturer.8.21 Sulfide Removal Acidification ReagentWeigh 1.00 gbismuth nitrate pentahydrate, Bi(NO3)35H2O,intoa1Lvolumetric flask. Add 55 mL of water then carefully, add 55mL of concentrated sulfuric acid to the flask. Gently, swirl theflask until the bism
