1、Designation: D6888 09D6888 16Standard Test Method forAvailable CyanideCyanides with Ligand Displacement andFlow Injection Analysis (FIA) Utilizing Gas DiffusionSeparation and Amperometric Detection1This standard is issued under the fixed designation D6888; the number immediately following the design
2、ation indicates 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
3、 the concentration of available inorganic cyanide in an aqueous wastewater or effluent. Themethod detects the cyanides that are free (HCN and CN-) and metal-cyanide complexes that are easily dissociated into free cyanideions. The method does not detect the less toxic strong metal-cyanide complexes,
4、cyanides that are not “amenable to chlorination.”1.2 Total cyanide can be determined for samples that have been distilled as described in Test Methods D2036, Test Method A,Total Cyanides after Distillation. The cyanide complexes are dissociated and absorbed into the sodium hydroxide capture solution
5、,which can be analyzed with this test method; therefore, ligand exchange reagents from Sections 8.12 and 8.13 would not berequired when determining total cyanide after distillation.1.3 This procedure is applicable over a range of approximately 2 to 400 g/L (parts per billion) available cyanide.cyani
6、des.Higher concentrations can be analyzed by dilution or lower injection volume.1.4 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.1.5 This standard does not purport to address all of the safety concerns, if any, associated w
7、ith its use. It is the responsibilityof the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatorylimitations prior to use. Specific hazard statements are given in Note 28.6 and Section 9.2. Referenced Documents2.1 ASTM Standards:2D11
8、29 Terminology Relating to WaterD1193 Specification for Reagent WaterD2036 Test Methods for Cyanides in WaterD2777 Practice for Determination of Precision and Bias of Applicable Test Methods of Committee D19 on WaterD3856 Guide for Management Systems in Laboratories Engaged in Analysis of WaterD4375
9、 Practice for Basic Statistics in Committee D19 on WaterD5847 Practice for Writing Quality Control Specifications for Standard Test Methods for Water AnalysisD6696 Guide for Understanding Cyanide SpeciesD7365 Practice for Sampling, Preservation and Mitigating Interferences in Water Samples for Analy
10、sis of CyanideE60 Practice for Analysis of Metals, Ores, and Related Materials by SpectrophotometryE275 Practice for Describing and Measuring Performance of Ultraviolet and Visible Spectrophotometers3. Terminology3.1 Definitions:3.1.1 For definitions of terms used in this standard, refer to Terminol
11、ogy D1129 and Guide D6696.3.2 Definitions:Definitions of Terms Specific to This Standard:3.1.1 For definitions of terms used in this test method, refer to Terminology D1129 and Guide D6696.1 This test method is under the jurisdiction of ASTM Committee D19 on Water and is the direct responsibility of
12、 Subcommittee D19.06 on Methods for Analysis forOrganic Substances in Water.Current edition approved Oct. 1, 2009Feb. 1, 2016. Published October 2009June 2016. Originally approved in 2003. Last previous addition approved in 20042009 asD6888 04.D6888 09. DOI: 10.1520/D6888-09.10.1520/D6888-16.2 For r
13、eferencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.This document is not an ASTM standard and is intended only to provid
14、e the user of an ASTM standard an indication of what changes have been made to the previous version. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current versionof the st
15、andard as published by ASTM is to be considered the official document.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States13.2.1 available cyanide,cyanides, nInorganic cyanides that are free (HCN and CN-) and metal-cyanide complexes that a
16、reeasily dissociated into free cyanide ions. Available cyanide does not include the less toxic strong metal-cyanide complexes,cyanides that are not “amenable to chlorination.”3.2.1.1 DiscussionAvailable cyanide does not include the less toxic strong metal-cyanide complexes, cyanides that are not “am
17、enable to chlorination”and includes weak acid dissociable or weak and dissociable (WAD) cyanides for use in the implementation of InternationalCyanide Management Code.4. Summary of Test Method4.1 Complex cyanides bound with nickel or mercury are released by ligand displacement by the addition of a l
18、iganddisplacement agent prior to analysis.agent, when necessary.4.2 Other weak and dissociable cyanide species do not require ligand displacement.4.3 The treated sample is introduced into a flow injection analysis (FIA) system where it is acidified to form hydrogen cyanide(HCN). The hydrogen cyanide
19、 gas diffuses through a hydrophobic gas diffusion membrane, from the acidic donor stream into analkaline acceptor stream.4.4 The captured cyanide is sent to an amperometric flowcell detector with a silver-working electrode. In the presence ofcyanide, silver in the working electrode is oxidized at th
20、e applied potential. The anodic current measured is proportional to theconcentration of cyanide in the standard or sample injected.4.5 Calibrations and data are processed with the instruments data acquisition software.5. Significance and Use5.1 Cyanide and hydrogen cyanide are highly toxic. Regulati
21、ons have been established to require the monitoring of cyanide inindustrial and domestic wastes and surface waters.35.2 This test method is applicable for natural water, saline waters, metallurgical process solutions, and wastewater effluent.5.3 The method may be used for process control in wastewat
22、er treatment facilities.6. Interferences6.1 High levels of carbonate can release CO2 into the acceptor stream and cause an interference with the amperometric detectorthat result in a slight masking effect (15 % negative bias with 20 ppb cyanide in 1500 ppm carbonate). Refer to 11.2 for samplepretrea
23、tment.6.2 Sulfide above 50 mg/L will diffuse through the gas diffusion membrane and can be detected in the amperometric flowcell.Oxidized products of sulfide can also rapidly convert CN- to SCN- at a high pH. Refer to Practice D7365 for sulfide removalprocedures.6.3 Refer to Practice D7365 for furth
24、er information on mitigating interferences in water samples for the analysis of cyanide.7. Apparatus7.1 The instrument should be equipped with a precise sample introduction system, a gas diffusion manifold with hydrophobicmembrane, and an amperometric detection system to include a silver working ele
25、ctrode, a Ag/AgCl reference electrode, and a Ptor stainless steel counter electrode. Examples of the apparatus schematics are shown in Figs. 1 and 1-23. Example instrumentsettings are shown in Table 1.4NOTE 1The instrument settings in Table 1 are only examples. The analyst may modify the settings as
26、 long as performance of the method has notbeen degraded. Contact the instrument manufacturer for recommended instrument parameters.7.2 An autosampler is recommended but not required to automate sample injections and increase throughput.Autosamplers areusually available as an option from the instrume
27、nts manufacturer.7.3 Data Acquisition SystemUse the computer hardware and software recommended by the instrument manufacturer tocontrol the apparatus and to collect data from the detector.7.4 Pump TubingUse tubing recommended by instrument manufacturer. Replace pump tubing when worn, or when precisi
28、onis no longer acceptable.3 40 CFR Part 136.4 OIAnalytical CNSolution 3100, FS3100, or Flow Solution IV and Lachat Instruments QuikChemAutomated IonAnalyzer using Method 10-204-00-5-Ahave been foundto be suitable for this analysis. If you are aware of alternative suppliers, please provide this infor
29、mation to ASTM International Headquarters. Your comments will receivecareful consideration at a meeting of the responsible technical committee,1 which you may attend.D6888 1627.5 Gas Diffusion MembranesA hydrophobic membrane which allows gaseous hydrogen cyanide to diffuse from the donorto the accep
30、tor stream at a sufficient rate to allow detection. The gas diffusion membrane should be replaced when the baselinebecomes noisy or every 1 to 2 weeks.57.6 Use parts and accessories as directed by instrument manufacturer.8. Reagents and Materials8.1 Purity of ReagentsReagent grade chemicals shall be
31、 used in all tests. Unless otherwise indicated, it is intended that allreagents shall conform to the specifications of the American Chemical Society, where such specifications are available.6 Othergrades may be used, provided it is first ascertained that the reagent is of sufficiently high purity to
32、 permit its use without lesseningthe accuracy of the determination.8.2 Purity of WaterUnless otherwise indicated, references to water shall be understood to mean reagent water conforming toType II grade of Specification D1193.8.3 Sodium Hydroxide Solution (1.00 M)Dissolve 40 g NaOH in laboratory wat
33、er and dilute to 1 L.8.4 Acceptor Solution A (0.10 M NaOH)Dissolve 4.0 g NaOH in laboratory water and dilute to 1 L.5 PALL Life Sciences Part Number M5PU025, OI AnaltyicalAnalytical Part Number A001520, and Lachat Instruments Part Number 50398 have found to be suitable forthis analysis.6 Reagent Che
34、micals, American Chemical Society Specifications , Am. Chemical Soc., Washington, DC. For suggestions on the testing of reagents not listed by theAmerican chemical Society, see Analar Standards for Laboratory Chemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeia.FIG. 1 Flow In
35、jection Analysis Apparatus 1FIG. 2 Flow Injection Apparatus 2 with Automated Ligand InjectionD6888 1638.5 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-)Dissolve 2.51 g of KCN and 2.0 g of NaOH in 1 L o
36、f water. Standardize withsilver nitrate solution as described in Test Methods D2036, sectionSection 16.2. Store the solution under refrigeration and checkconcentration approximately every 6 months and correct if necessary.7 (WarningBecause KCN is highly toxic, avoid contactor inhalation.)NOTE 2Warni
37、ng: Because KCN is highly toxic, avoid contact or inhalation.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 a 100-mLvolumetric flask containing 1 mL of 1.0 M NaOH (see 8.3). Dilute to volume with laborat
38、ory water. Store under refrigeration. Thestandard 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) intoa 100-mL volumetric flask containing 1.0 mL of 1.00 M NaOH (see 8.3). Dilute to volume with laboratory
39、 water. Store underrefrigeration. The standard should be stable for 6 months.8.8 Working Cyanide Calibration StandardsPrepare fresh weekly 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/L CN-)Pipette 20, 50, 100,
40、 200, and 400 L of IntermediateCyanide Standard 1 (see 8.7.1) into separate 100-mL volumetric flasks containing 1.0 mL of 1.00 M NaOH (see 8.3). Dilute tovolume with laboratory water.8.8.2 Calibration Standards (2 and 10 g/L CN-)Pipette 20 and 100 L of Intermediate Cyanide Standard 2 (see 8.7.2) int
41、oseparate 100-mL volumetric flasks containing 1.0 mL of 1.00 M NaOH (see 8.3). Dilute to volume with laboratory water.7 Commerical Solutions of Stock Cyanide may be substituted.FIG. 23 Flow Injection Analysis Apparatus 23TABLE 1 Flow Injection Analysis ParametersFIA InstrumentParameterRecommendedMet
42、hod SettingPump Flow Rates 0.5 to 2 mL/minCycle period (total) 90 to 250 s/sampleSample load period At least enough time tocompletelyfill the sample loopReagent water rinse timebetween samplesAt least 15 secondsPeak Evaluation Peak height or areaWorking Potential 0.0 V vs Ag/AgClD6888 1648.9 Cyanide
43、 Electrode Stabilization Solution (2 mg/L as CN-)Pipette 200 L of Stock Cyanide (see 8.6) into a 100-mLvolumetric flask containing 1.0 mL of 1.00 M NaOH (see 8.3). Dilute to volume with laboratory water. The solution should bestored under refrigeration.8.10 Acetate BufferDissolve 410 g of sodium ace
44、tate trihydrate (NaC2H3O23H2O) in 500 mLof laboratory water.Add glacialacetic acid (approximately 500 mL) to yield a pH of 4.5.8.11 Carrier AUse water as the carrier.8.12 Ligand Exchange Reagent 1 (TEP Solution)Weigh 0.10 g tetraethylenepentamine (TEP) into a 100-mL volumetric flask.Dilute to volume
45、 with laboratory water. The solution should be stored at room temperature.8.13 Ligand Exchange Reagent 2 (Dithizone Solution)Weigh 0.010 g of dithizone into a 100-mL volumetric flask containing1.0 mL of 1.00 M NaOH (see 8.3). Dilute to volume with laboratory water. Sonicate if necessary until all of
46、 the dithizone hasdissolved. The solution should be stored at room temperature.NOTE 2Commercially prepared or alternative ligand exchange reagents can be used if equivalent results can be demonstrated. Commercial reagentsshould be used in accordance with manufacturers instructions.88.14 Mixed Ligand
47、 Exchange Reagent, for automated ligand addition as shown in Fig. 2Transfer 0.125 millilitres of WADReagent A and 0.250 milliliters of WAD Reagent B8 into a 100-mL volumetric flask containing 50-mL laboratory water. Diluteto volume with laboratory water and mix. The solution should be stored at room
48、 temperature8.15 Mercury (II) Cyanide Stock SolutionWeigh 0.4854 g Hg(CN)2 into a 100-mL volumetric flask. Place 1.0 mL of 1.00 MNaOH (see 8.3) in the flask and dilute to volume with laboratory water. Hg(CN)2 as CN- = 1000 mg/L. The solution must be storedin an amber glass bottle under refrigeration
49、. The standard should be stable for 6 months.8.16 Mercury (II) Cyanide Intermediate SolutionPipet 10.0 mL of the mercury (II) cyanide stock solution (see 8.148.15) intoa 100-mL volumetric flask containing 1.0 mL of 1.00 M NaOH (see 8.3). Dilute to volume with laboratory grade water. Hg(CN)2as CN- = 100 mg/L. The solution must be stored in an amber glass bottle under refrigeration. The standard should be stable for6 months.8.17 Mercury (II) Cyanide Recovery SolutionPipet 100 L of mercury II cyanide intermediate solution (see 8.158.1
