1、Designation: D 6888 09Standard 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 () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This method is used to determine the concentra
3、tion 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 a
4、renot “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 ana
5、lyzed 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 c
6、an be analyzed by dilution or lowerinjection volume.1.4 The values stated in SI 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 theresponsib
7、ility 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. Specific hazardstatements are given in Note 2 and Section 9.2. Referenced Documents2.1 ASTM Standards:2D 1129 Terminology Relating to Wate
8、rD 1193 Specification for Reagent WaterD 2036 Test Methods for Cyanides in WaterD 2777 Practice for Determination of Precision and Bias ofApplicable Test Methods of Committee D19 on WaterD 3856 Guide for Good Laboratory Practices in Laborato-ries Engaged in Sampling and Analysis of WaterD 4375 Pract
9、ice 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 SpeciesD 7365 Practice for Sampling, Preservation and MitigatingInterferences in Water Samples for Analysis of
10、 CyanideE60 Practice for Analysis of Metals, Ores, and RelatedMaterials by Molecular Absorption SpectrometryE 275 Practice for Describing and Measuring Performanceof Ultraviolet and Visible Spectrophotometers3. Terminology3.1 DefinitionsFor definitions of terms used in this testmethod, refer to Term
11、inology D 1129 and Guide D 6696.3.2 available cyanide, nInorganic 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 complexes, cya-nides that are not “amenable to ch
12、lorination.”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 displacement.4.3 The treated sample is introdu
13、ced 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.4.4 The captured cyanide is sent to an amperometric flow-cel
14、l detector with a silver-working electrode. In the presence ofcyanide, silver in the working electrode is oxidized at the1This 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 W
15、ater.Current edition approved Oct. 1, 2009. Published October 2009. Originallyapproved in 2003. Last previous addition approved in 2004 as D 6888 04.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStanda
16、rds volume information, refer to the standards Document Summary page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.applied potential. The anodic current measured is proportionalto the concentration of cyanide in
17、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 monitoring ofcyanide in industrial and domestic wastes an
18、d surface waters.35.2 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.6. Interferences6.1 High levels of carbonate can release CO2into theacceptor stream and cause an interferen
19、ce with the amperomet-ric detector that result in a slight masking effect (15 % negativebias with 20 ppb cyanide in 1500 ppm carbonate). Refer to 11.2for sample pretreatment.6.2 Sulfide above 50 mg/L will diffuse through the gasdiffusion membrane and can be detected in the amperometricflowcell. Oxid
20、ized products of sulfide can also rapidly convertCN-to SCN-at a high pH. Refer to Practice D 7365 for sulfideremoval procedures.6.3 Refer to Practice D 7365 for further information onmitigating interferences in water samples for the analysis ofcyanide.7. Apparatus7.1 The instrument should be equippe
21、d with a precisesample introduction system, 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
22、Figs. 1 and 2.Example instrument settings are shown in Table 1.4NOTE 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 au
23、tosampler is recommended but not required toautomate 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
24、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 hydrophobic membranewhich allows gaseous hydrogen cyanide to diffuse from thedonor to
25、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.57.6 Use parts and accessories as directed by instrumentmanufacturer.340 CFR Part 136.4OI Analytical CNSolution 3100, FS3100, or Flow Solutio
26、n IV and LachatInstruments QuikChem Automated Ion Analyzer using Method 10-204-00-5-A havebeen found to be suitable for this analysis. If you are aware of alternative suppliers,please provide this information to ASTM International Headquarters. Your com-ments will receive careful consideration at a
27、meeting of the responsible technicalcommittee,1which you may attend.5PALL Life Sciences Part Number M5PU025, OI Analtyical Part NumberA001520, and Lachat Instruments Part Number 50398 have found to be suitable forthis analysis.FIG. 1 Flow Injection Analysis Apparatus 1D68880928. Reagents and Materia
28、ls8.1 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.6Other grades may be used, provided it is first ascertain
29、ed 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 reagent water conformingto Type II grade of Specification D 1193.8.3 Sodium Hydroxide S
30、olution (1.00 M)Dissolve 40 gNaOH in laboratory water and dilute to 1 L.8.4 Acceptor Solution 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
31、(1000 g/mL CN-)Dissolve2.51 g of KCN and 2.0 g of NaOH in 1 L of water. Standardizewith silver 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.7NOTE 2Warning: Because
32、 KCN is highly toxic, avoid contact orinhalation.8.7 Intermediate Cyanide Standards:8.7.1 Intermediate Cyanide Standard 1 (100 g/mL CN-)Pipette 10.0 mL of stock cyanide solution (see 8.6) into a100-mL volumetric flask containing 1 mL of 1.0 M NaOH (see8.3). Dilute to volume with laboratory water. St
33、ore underrefrigeration. The standard should be stable for 6 months.8.7.2 Intermediate Cyanide Standard 2 (10 g/mL CN-)Pipette 10.0 mL of Intermediate Cyanide Standard 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. Storeu
34、nder refrigeration. The standard should be stable for 6months.8.8 Working Cyanide Calibration StandardsPrepare freshweekly 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 o
35、f IntermediateCyanide Standard 1 (see 8.7.1) into separate 100-mL volumet-ric flasks containing 1.0 mL of 1.00 M NaOH (see 8.3). Diluteto volume with laboratory water.8.8.2 Calibration Standards (2 and 10 g/L CN-)Pipette20 and 100 L of Intermediate Cyanide Standard 2 (see 8.7.2)into separate 100-mL
36、volumetric flasks containing 1.0 mL of1.00 M NaOH (see 8.3). Dilute to volume with laboratorywater.6Reagent Chemicals, American Chemical Society Specifications , Am. ChemicalSoc., Washington, DC. For suggestions on the testing of reagents not listed by theAmerican chemical Society, see Analar Standa
37、rds for Laboratory Chemicals, BDHLtd., Poole, Dorset, U.K., and the United States Pharmacopeia.7Commerical Solutions of Stock Cyanide may be substituted.FIG. 2 Flow Injection Analysis Apparatus 2TABLE 1 Flow Injection Analysis ParametersFIA InstrumentParameterRecommendedMethod SettingPump Flow Rates
38、 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/AgClD68880938.9 Cyanide Electrode Stabilization S
39、olution (2 mg/L asCN-)Pipette 200 L of Stock Cyanide (see 8.6) into a100-mL volumetric flask containing 1.0 mL of 1.00 M NaOH(see 8.3). Dilute to volume with laboratory water. The solutionshould be stored under refrigeration.8.10 Acetate BufferDissolve 410 g of sodium acetatetrihydrate (NaC2H3O23H2O
40、) in 500 mL of laboratory water.Add glacial acetic acid (approximately 500 mL) to yield a pHof 4.5.8.11 Carrier AUse water as the carrier.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 s
41、olutionshould be stored at room temperature.8.13 Ligand Exchange Reagent 2 (Dithizone Solution)Weigh 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. Th
42、e solution should be stored at roomtemperature.NOTE 3Commercially prepared or alternative ligand exchange re-agents can be used if equivalent results can be demonstrated. Commercialreagents should be used in accordance with manufacturers instructions.88.14 Mercury (II) Cyanide Stock SolutionWeigh 0.
43、4854 gHg(CN)2into a 100-mL volumetric flask. Place 1.0 mL of 1.00M NaOH (see 8.3) in the flask and dilute to volume withlaboratory water. Hg(CN)2as CN-= 1000 mg/L. The solutionmust be stored in an amber glass bottle under refrigeration. Thestandard should be stable for 6 months.8.15 Mercury (II) Cya
44、nide Intermediate SolutionPipet10.0 mL of the mercury (II) cyanide stock solution (see 8.14)into a 100-mL volumetric flask containing 1.0 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 refrig
45、eration. The standard should bestable for 6 months.8.16 Mercury (II) Cyanide Recovery SolutionPipet 100L of mercury II cyanide intermediate solution (see 8.15) intoa 100-mL volumetric 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. Prep
46、are fresh weekly.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 diluteto volume with laboratory water. K2Ni(CN)4as CN-= 1000mg/L. The solution must be stored in an amber glass bottleunder r
47、efrigeration. The standard should be stable for 6months.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 containing 1.0 mL of1.00 M NaOH (see 8.3). Dilute to volume with laboratorygrade water. K2N
48、i(CN)4as CN-= 100 mg/L. The solution mustbe stored in an amber glass bottle under refrigeration. Thestandard should be stable for 6 months.8.19 Potassium Nickel Cyanide Recovery SolutionPipet100 L of potassium nickel cyanide intermediate solution (see8.18) into a 100-mLvolumetric flask containing 1.
49、0 mLof 1.00M NaOH (see 8.3). Dilute to volume with laboratory water.K2Ni(CN)4as CN-= 100 g/L. Prepare fresh weekly.8.20 Ag/AgCl Reference Electrode Filling SolutionFillthe reference electrode as recommended by the instrumentmanufacturer.8.21 Sulfide Removal and Acidification ReagentWeigh1.00 g bismuth nitrate pentahydrate, Bi(NO3)35H2O, into a1-L volumetric flask. Add 55 mL of water then carefully, add55 mL of concentrated sulfuric acid to the flask. Gently swirlthe flask until the bismuth nitrate pentahydrate has dissolved inthe ac
