1、Designation: E1064 12E1064 16Standard Test Method forWater in Organic Liquids by Coulometric Karl FischerTitration1This standard is issued under the fixed designation E1064; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year
2、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. Scope*1.1 This test method covers the determination of water from 0 to 2.0 % mass in most liquid organic chemicals, with Kar
3、l Fischerreagent, using an automated coulometric titration procedure. Use of this test method is not applicable for liquefied gas productssuch as Liquid Petroleum Gas (LPG), Butane, Propane, Liquid Natural Gas (LNG), etc.1.2 The values stated in SI units are to be regarded as standard. No other unit
4、s of measurement are included in this standard.1.3 Review the current material safety data sheets (MSDS) Safety Data Sheets (SDS) for detailed information concerningtoxicity, first-aid procedures, handling, and safety precautions.1.4 This standard does not purport to address all of the safety proble
5、ms, if any, associated with 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 precautionary statements are given in Section 8.2. Referenced Documents2.1 AS
6、TM Standards:2D1193 Specification for Reagent WaterD4672 Test Method for Polyurethane Raw Materials: Determination of Water Content of PolyolsE180 Practice for Determining the Precision of ASTM Methods for Analysis and Testing of Industrial and Specialty Chemicals(Withdrawn 2009)3E203 Test Method fo
7、r Water Using Volumetric Karl Fischer Titration3. Summary of Test Method3.1 This test method is based on the Karl Fischer reaction for determining waterthe reduction of iodine by sulfur dioxide inthe presence of water to form sulfur trioxide and hydriodic acid. The reaction becomes quantitative only
8、 when pyridine or otherorganic base and methanol or other alcohol are present. Unlike the volumetric Karl Fischer reagents that include iodine, thecoulometric technique electrolytically generates iodine, with 10.71 C of generating current corresponding to 1 mg of water inaccordance with Faradays law
9、.4. Significance and Use4.1 The coulometric technique is especially suited for determining low concentrations of water in organic liquids that wouldyield small titers by the Karl Fischer volumetric procedure. The precision and accuracy of the coulometric technique decreases forconcentrations of wate
10、r much greater than 2.0 % because of the difficulty in measuring the small size of sample required. The testmethod assumes 100 % efficiency of coulombs in iodine production. Provision is made for verifying this efficiency. (See Table1Table 1 and Note 6.)5.)1 This test method is under the jurisdictio
11、n of ASTM Committee E15 on Industrial and Specialty Chemicals and is the direct responsibility of Subcommittee E15.01 onGeneral Standards.Current edition approved April 1, 2012April 1, 2016. Published May 2012May 2016. Originally approved in 1985. Last previous edition approved in 20082012 asE1064 0
12、8.E1064 12. DOI: 10.1520/E1064-12.10.1520/E1064-16.2 For referencedASTM 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.3 The last
13、 approved version of this historical standard is referenced on www.astm.org.This document is not an ASTM standard and is intended only to provide 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
14、 depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current versionof the standard as published by ASTM is to be considered the official document.*A Summary of Changes section appears at the end of this standardCopyright ASTM Intern
15、ational, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States15. Interferences5.1 Interfering substances are the same as are encountered in the volumetric Karl Fischer titration. A detailed discussion ofinterfering substances can be found in the treatise on “Aquametry.
16、”45.2 Test Method E203 discusses organic compounds in which water may be determined directly and compounds in which watercannot be determined directly, but in which interferences may be eliminated by suitable chemical reactions.6. Apparatus6.1 Automatic Titrator,5consisting consisting of a control u
17、nit, titration vessel, dual platinum sensing electrode, generatorassembly, and magnetic stirrer. The instrument is designed to coulometrically generate iodine that reacts stoichiometrically withthe water present in the sample solution. The coulombs of electricity required to generate the reagent are
18、 converted to microgramsof water, which is obtained as a direct digital readout.6.2 Syringe, 50-mL, fitted with an 115-mm hypodermic needle for removing excess solution from the titration chamber.NOTE 1Rinse all glass syringes and needles with anhydrous acetone after cleaning, then dry in an oven at
19、 100C for at least 1 h and store in adesiccator. Plastic syringes shall be disposed of following use.6.3 Syringe, 20-mL, fitted with an 115-mm hypodermic needle for introduction of neutralizing solution into the titrationchamber (see Note 1).6.4 Syringes, 1- and 5-mL, fitted with 115-mm hypodermic n
20、eedles for introduction of samples into titration chamber (see Note1).6.5 Syringe, 5 L, fitted with 115-mm hypodermic needle for standardization of instrument (see Note 1).6.6 Fluorocarbon Sealing Grease or TFE-Fluorocarbon, to seal the titration chamber against atmospheric moisture.6.7 Septa, to se
21、al sample port but allow introduction of samples by a needle with a minimum of moisture contamination.Replace serum caps and septa as required to prevent air leakage as indicated by instrument drift.6.8 Serum Bottles. Serum Bottles.6.9 Oven, temperature 100 6 5C.6.10 Dessicator, standard laboratory
22、type with color change indicator.6.11 Analytical Balance, capable of weighing to 60.0001 g.7. Reagents7.1 Purity of ReagentsUnless otherwise indicated, it is intended that all reagents shall conform to the specifications of theCommittee onAnalytical Reagents of theAmerican Chemical Society, where su
23、ch specifications are available.6 Other grades maybe used, provided it is first ascertained that the reagent is of sufficiently high purity to permit its use without lessening the accuracyof the determination.7.2 Purity of WaterUnless otherwise indicated, reference to water shall be understood to me
24、an Type II or Type III reagentwater, conforming to Specification D1193.7.3 Karl Fischer ReagentsCommercial coulometric KF reagents and reagent systems of various types are available for usewith autotitrators for water determination. Traditionally, pyridine was the organic base used in KF reagents. P
25、yridine-freeformulations are available and are preferred by most KF instrument manufacturers for use with their equipment. The pyridine-freereagents are less toxic, less odorous, and more stable than those containing pyridine. The use of pyridine-free reagents isrecommended whenever possible. Coulom
26、etric titrations normally require two reagent solutions. An anolyte or solvent titration4 J. Mitchell, Jr. and D. M. Smith, “Aquametry”A Treatise on Methods for the Determination of Water, Part IIIThe Karl Fischer Reagent, 2nd Ed., J. Wiley and Sons,Inc., New York, NY 1990.5 Basic references to the
27、automatic coulometric titrator: M. T. Kelley, R. W. Stelzner, W. R. Laing, and D. J. Fisher, Analytical Chemistry 31, No. 2, 220 (1959) and A.W. Meyer, Jr. and C. M. Boyd, Analytical Chemistry 31, No. 2, 215 (1959).6 Reagent Chemicals, American Chemical Society Specifications , American Chemical Soc
28、iety, Washington, DC. For suggestions on the testing of reagents not listed bythe American Chemical Society, see Analar Standards for Laboratory Chemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeia and NationalFormulary, U.S. Pharmacopeial Convention, Inc. (USPC),(USP), Rockv
29、ille, MD.TABLE 1 Sample Size EstimationExpected Water Content Sample Size, mL0 to 500 mg/kg 5500 to 1000 mg/kg 21000 to 2000 mg/kg 10.2 to 0.5 % mass 0.50.5 to 2.0 % mass 0.1E1064 162solution and a catholyte or generator titrant solution. However, now reagents can be purchased in one or two componen
30、t reagentsystems. A one component reagent system contains all the components required for a Karl Fischer titration in a single solution.A two component system incorporates separate solutions for the solvent and titrant.NOTE 2Two good references on pyridine-free reagents are the Hydranal Manual-Eugen
31、 Schotz Reagents for Karl Fischer Titration, fromRiedel-deHaen (www.rdhlab.de) or Sigma Aldrich (www.sigma-) and Moisture Measurement by Karl Fischer Titrimetry, 2nd ed., by GFSChemicals, Inc., January 2004.7.3.1 Generator Titrant Solution (catholyte), containing iodine, sulfur dioxide, pyridine or
32、other organic base and methanol orother alcohol to provide iodine in the reaction mixture.7.3.2 Solvent Titration Solution (anolyte), prepared as per instrument specifications.7.3.3 Neutralizing Solution, methanol containing approximately 20 mg H2O/mL.8. Safety Precautions8.1 The reagents contain on
33、e or more of the following: iodine, pyridine or other organic base, sulfur dioxide, and methanol orother alcohol. Wear chemical resistant gloves when mixing the reagents and removing solution from the titration chamber. Caremust be exercised to avoid inhalation of reagent vapors, or direct contact o
34、f the reagent with the skin.9. Sampling9.1 Because of the low concentration of water to be measured, maximum care must be exercised at all times to avoidcontaminating the sample with moisture from the sample container, the atmosphere, or transfer equipment.9.1.1 Dry the sample bottles and caps overn
35、ight in an oven at 100C before using. Allow to cool in a desiccator before fillingand sealing.9.1.2 Fill the sample bottle as rapidly as possible to within 25 mm of the top and immediately seal.9.2 Remove the test specimens for analysis from the sample bottle with a dry hypodermic syringe. Inject dr
36、y nitrogen into thesample bottle with the syringe to displace the sample that is removed.10. Preparation of Apparatus10.1 Clean, dry, and assemble the titration chamber as directed in the manufacturers instructions. Use fluorocarbon grease orTFE-fluorocarbon to seal the upper and lower sections of t
37、he chamber from atmospheric moisture. Connect the leads from thesensing and generator electrodes to the titrator.10.2 Prepare the titration solution (7.3.2) as directed by the instrument manufacturer and fill the instrument reservoir as directedby the manufacturer.10.3 Add the generator solution (7.
38、3.1) to the generator assembly and replace the cover cap. The surface of the generatorsolution must be below the level of the titration solution to prevent backflow contamination of the titration solution. The generatorsolution may have to be removed periodically to maintain the lower level.10.4 Agi
39、tate the titration solution by gently swirling the titration chamber to remove any residual moisture from the walls.Allowthe solution to stir for at least 20 min to dry and stabilize the inner atmosphere.Follow the manufacturers procedure to dry thetitration cell.NOTE 3Mitsubishi automatic moisture
40、analyzers do not require the steps in 10.4.10.5 Attach an 11.5-cm hypodermic needle to a 20-mLsyringe and withdraw about 15 mLof neutralizing solution (7.3.3). Insertthe needle through the sample port septum and lower it until the tip is just below the surface of the titration solution.10.6 Slowly i
41、nject the neutralizing solution into the titration solution until the color changes from brown to light red. Thisindicates that the end point is near. Continue the addition very slowly until the ON light comes on, indicating an excess of wateris present, then carefully withdraw the syringe and needl
42、e. The total volume of neutralizing solution required will range from 5to 15 mL. Allow the system to stabilize for 1 h.11. Verification of Calibration11.1 Different autotitrators may vary in calibration procedures. Consult the operating manual for the autotitrator in use. Stable,prepackaged Quality
43、Control (QC) water standards are commercially available with 10 mg/kg. 100 mg/kg and 1 % (m/m) watercontent for this purpose. It is desirable to verify calibration with a standard solution that approximates the same range of waterexpected to be in the samples.11.2 It is recommended that a control ch
44、art measuring a QC standard sample be established and maintained according togenerally accepted guidelines.7 Measure the control sample each time a test sample(s) is tested. If the measured value exceeds 65% of the known amount, take appropriate action before proceeding with the sample test.7 ASTM M
45、anual on Presentation of Data and Control ChartAnalysis, 7th Edition,ASTM Manual Series MNL 7A, (revision of Special Technical Publication (STP) 15D).E1064 163NOTE 3This may require replacing or regenerating the reagent solutions.12. Procedure12.1 Assemble a dry syringe and needle and attach a small
46、 piece of rubber septum to the needle tip. Withdraw 1 to 2 mL ofthe sample into the syringe and discard the contents into a waste container. Using the following table as a guide, withdraw theproper amount of test sample into the syringe and seal with the rubber septum. Obtain a tare weight to60.1 mg
47、. See Table 1, Note54 and Note 65.NOTE 4If multiple analyses are performed on the same test sample or if an appreciable volume of test sample is withdrawn, a slight pressure shouldbe maintained on the sample bottle by means of a hypodermic needle attached to a dry nitrogen source.NOTE 5Alternatively
48、, if syringes of suitable accuracy are available, a measured volume of sample can be injected and the mass calculated from thevolume and density.12.2 With the analyzer stabilized, carefully insert the needle of the sample syringe through the septum and below the level ofsolution in the titration cha
49、mber. Inject the sample slowly into the titration solution and begin titration. Withdraw the syringeneedle, seal and again weigh to the nearest 60.1 mg to determine the exact sample mass. Allow the titration to proceed until theend-point is indicated. Record the micrograms of water determined.NOTE 6After numerous analyses, the level of solvent accumulated in the titration chamber may have to be reduced. This can be accomplished witha 50-mL syringe or by partially draining the solution if the titration chamber is provided with a stopcock. Discard
copyright@ 2008-2019 麦多课文库（www.mydoc123.com）网站版权所有
备案/许可证编号：苏ICP备17064731号-1