1、Designation: D2988 96 (Reapproved 2015)Standard Test Methods forWater-Soluble Halide Ion in Halogenated Organic Solventsand Their Admixtures1This standard is issued under the fixed designation D2988; the number immediately following the designation indicates the year oforiginal adoption or, in the c
2、ase 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.This standard has been approved for use by agencies of the U.S. Department of Defense.1. Scope1.1 Tes
3、t Methods 1, 2, and 3These test methods cover thedetermination of water-extractable halide ion in halogenatedorganic solvents and their admixtures. Fluoride ion is notmeasured due to the solubility of silver fluoride.1.2 Test Method 4This test method covers the determina-tion of chloride ion in halo
4、genated organic solvents and theiradmixtures.1.3 The values stated in SI units are to be regarded asstandard. No other units of measurement are included in thisstandard.1.4 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility o
5、f 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 precau-tionary statements are given in Section 6.2. Summary of Test Method2.1 Summary of Test Methods 1, 2, 3Halide ion present inhaloge
6、nated organic solvents is extracted with water andprecipitated as the silver halide salt with silver nitrate. Quantityof the halide present is determined by comparing the turbidityof the sample to known standards. The distilled water, as wellas all glassware used, must be halide-free.2.2 Summary of
7、Test Method 4This test method is basedon the determination of ionizable chloride by titration withmercuric acetate solution using s-diphenylcarbazone as theindicator.3. Significance and Use3.1 These test methods are used to establish manufacturingand purchasing specifications. These test methods wil
8、l providea means of determining the condition of the solvent in use. Ahigh water soluble chloride level may indicate the start ofsolvent decomposition.4. Apparatus4.1 Separatory Funnel, 500-mL,4.2 Nessler Tubes, 50-mL,4.3 Erlenmeyer Flask, 125-mL, and4.4 Colorimeter or Turbidimeter, Method 2.5. Reag
9、ents5.1 Purity of ReagentsReagent grade chemicals shall beused in all test. Unless otherwise indicated it is intended that allreagents shall conform to the specifications of the Committeeon Analytical Reagents of the American Chemical Society,where such specification are available.2Other grades may
10、beused, provided it is first ascertained that the reagent is ofsufficiently high purity to permit its use without lessening theaccuracy of the determination.5.2 Purity of WaterUnless otherwise indicated, referencesto water shall be understood to mean halide-free distilled water.5.3 Chloride Standard
11、 (1 mL 0.0001 g Cl), Test Methods1, 2, and 3Prepare by adding 0.165 g of sodium chloride(NaCl) to 1 L of halide-free distilled water.5.4 Chloride Standard (1 mL = 0.000001 g Cl), TestMethod 4Dissolve 0.0660 g of sodium chloride in water anddilute to 1000 mL. Pipet 25 mLof this solution into a 1000-m
12、Lvolumetric flask, dilute to volume, and mix.5.5 Nitric Acid (sg gr 1.42), concentrated nitric acid(HNO3).5.6 Silver Nitrate Solution 0.1 NPrepare a 0.1 N solutionof silver nitrate (AgNO3).1These test methods are under the jurisdiction of ASTM Committee D26 onHalogenated Organic Solvents and Fire Ex
13、tinguishing Agents and are the directresponsibility of Subcommittee D26.04 on Test Methods.Current edition approved June 1, 2015. Published June 2015. Originallyapproved in 1971. Last previous edition approved in 2010 as D2988 96(2010).DOI: 10.1520/D2988-96R15.2Reagent Chemicals, American Chemical S
14、ociety Specifications, AmericanChemical Society, Washington, DC. For suggestions on the testing of reagents notlisted by the American Chemical Society, see Analar Standards for LaboratoryChemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeiaand National Formulary, U.S. Pharmaco
15、peial Convention, Inc. (USPC), Rockville,MD.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States15.6.1 Prepare the silver nitrate solution by adding 16.99 g ofsilver nitrate to a 1-L volumetric flask and fill to the line withhalide-free di
16、stilled water. After shaking to dissolve theAgNO3, store in an amber bottle.5.7 Mercuric Acetate Solution, Test Method 4.5.7.1 Stock Mercuric Acetate SolutionDissolve 1.6 g ofmercuric acetate in 500 mLof water containing 3.5 mLof nitricacid. Dilute to 1000 mL and mix.5.7.2 Standard Mercuric Acetate
17、SolutionDilute 40 mL ofstock mercuric acetate solution to 1000 mL and adjust the pHto 1.6 with nitric acid. Standardize in accordance with 7.5.5.5.7.3 s-Diphenylcarbazone Solution (Test Method 4)Dissolve 0.5 g of s-diphenylcarbazone in 100 mL of methanol.6. Hazards6.1 Solvent HazardsContact with the
18、 skin should beavoided to prevent removal of natural oils. There are varyingdegrees of danger to inhalation, ingestion, and contact. Theuser should refer to the most recent health regulations concern-ing the individual solvent.6.2 Concentrated nitric acid is very hazardous in contactwith the skin or
19、 eyes. The vapors are very toxic and corrosive.6.3 (WarningWear safety glasses and rubber gloveswhen handling the silver nitrate or its solution.)6.4 Mercuric acetate is toxic.6.5 The hazards of s-diphenylcarbazone are not known.7. Procedure7.1 Test Method 1:7.1.1 Transfer 100 mL of sample to a sepa
20、ratory funnel andadd an equal volume of halide-free distilled water. Shakevigorously for 2 min to extract the water-soluble halides (seeNote 1).7.1.2 Allow the liquids to separate and discard the solventlayer. Transfer 50 mLof the water extract into a 50-mLNesslertube and add ten drops of concentrat
21、ed nitric acid. Preparestandard chloride ion solutions in 50-mL Nessler tubes byadding a volume of standard chloride solution, in millilitres,equal to the density of the solvent being tested divided by twofor each part per million (ppm) of equivalent chloride iondesired (see Note 2). Dilute each sta
22、ndard with halide-freedistilled water to 50 mL and add ten drops of concentratednitric acid. Finally, add 1 mL of 0.1 N silver nitrate solution toeach sample and standard and shake the Nessler tubes thor-oughly for 30 s. Compare the sample with standards todetermine chloride level (see Note 3).NOTE
23、1This extraction time should be consistent. Slow hydrolyzingorganics such as phosgene and trichloroacetyl chloride require approxi-mately 2 min to react completely. Excessive time, however, can permit thehalogenated solvent itself to hydrolyze.NOTE 2For example, if trichloroethylene were being teste
24、d, 1.46/2 or0.73 mL of standard chloride solution would be needed for each part permillion (ppm) of chloride ion desired. For 2 ppm, 0.732=1.5 mLwould be added. Since the water-soluble halides are usually less than 1ppm, it will seldom be necessary to prepare more than one or twostandards.NOTE 3The
25、standards and samples should be prepared simultane-ously.To minimize effects of entrained air and changing character of silverchloride turbidity, let the samples set for 15 min in the dark. This waitingperiod is especially important when low chlorides (less than 1 ppm) arebeing determined. Dark stor
26、age prevents change in the silver nitrateconcentration.7.2 Test Method 1AThe accuracy of Test Method 1 can beimproved for samples with chloride levels less than 2 ppm byincreasing the solvent-water ratio from 1:1 to 4:1.7.3 Test Method 2Read the turbidity of standards preparedas described in Test Me
27、thods 1 and 1A using a colorimeter ora turbidimeter. Set up a graph to determine chloride levels insamples.7.4 Test Method 3Extract the sample as described in TestMethod 1. Analyze the water extract with an ion chromato-graph that has been calibrated with standards in the appropriateranges. This tes
28、t method gives superior data over turbiditymethods.7.5 Test Method 4:7.5.1 Wash all glassware with chloride-free water until 10mL of the washings show no trace of turbidity when 1 mL ofsilver nitrate solution is added.7.5.2 Transfer 100 mL of the sample into a 250-mL sepa-ratory funnel, add 25 mL of
29、 chloride-free water to the sampleand shake for 1 min. Transfer the sample to a second 250-mLseparatory funnel and drain the water into a 125-mL Erlen-meyer flask. Repeat the extraction once with another 25 mL ofwater. Combine the water extracts in the Erlenmeyer flask.7.5.3 Warm the water extract t
30、o 60C to drive off anyremaining sample. Cool to room temperature.7.5.4 Add five drops of s-diphenylcarbazone solution andtitrate with standard mercuric acetate solution to the palepurple end point.7.5.5 Pipet 10.00 mL of standard sodium chloride solutioninto a 250-mL Erlenmeyer flask. Add 20 mL of c
31、hloride-freewater and five drops of s-diphenylcarbazone solution. Titratewith standard mercuric acetate solution to the faint purple endpoint. Then:mL NaCl 31.00mL mercuric acetate5 F 5 g Cl/mL (1)where:F = factor for the mercuric acetate solution.7.5.6 CalculationCalculate parts per million chlorid
32、e asfollows:Chloride, ppm 5 A 3 F!/S 3 G! (2)where:A = mercuric acetate solution required for the titration, mL,F = factor for the solution (see 7.5.5),S = sample, mL, andG = specific gravity of the sample.8. Report8.1 Report the following information:8.1.1 Test Methods 1, 2, and 3Compare the turbid
33、ity ofthe sample with the standards and report halides as nonedetected, trace, or actual ppm water soluble halides. Note thatTest Method 3 is specific to individual halides such as chlorideor bromide. Comparisons of sample and standards can be madeD2988 96 (2015)23 min after preparation for qualitat
34、ive or semiquantitative data.Since the turbidity of these mixtures changes on standing, thesamples should set in the dark for 15 min before comparison.This gives the best quantitative data.8.1.2 Test Method 4Report ppm chloride.9. Precision and Bias9.1 Test Methods 1, 2, and 3:9.1.1 The precision li
35、mits of Test Method 1 have beendetermined as 61 ppm at levels below 5 ppm water-solublehalide ion (see Note 4). Using Test Method 1A and TestMethod 2 in combination yield precision limits of 60.3 ppm.Test Method 3, using an ion chromatograph, gives precisionlimits of 60.1 ppm.NOTE 4Precision of data
36、 statements have not been documented byformal precision test. These values are believed to be accurate based onrepeatability of a number of standards.9.2 Test Method 4:9.2.1 Repeatability (Single Analyst)The standard devia-tion of results (each the average of triplicates obtained by thesame analyst
37、on two different days) has been estimated to be0.005 weight ppm at 4 df. Two such values should beconsidered suspect (95 % confidence level) if they differ bymore than 0.02 weight ppm.9.2.2 Reproducibility (Multilaboratory)The standard de-viation of results (each the average of triplicates in fourdi
38、fferent laboratories) has been estimated to be 0.06 weightppm at 3 df. Two such values should be considered suspect(95 % confidence level) if they vary by more than 0.3 weightppm.10. Keywords10.1 chloride; halide; halide ion; halogenated; ion; ionchromatograph; solvent; turbidityASTM International t
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