1、Designation:E106408 Designation: E1064 12Standard 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 revisio
2、n, 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 Department of Defense.1. Scope*1.1 This test method cove
3、rs the determination of water from 0 to 2.0 % mass in most liquid organic chemicals, with Karl 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 G
4、as (LNG), etc.1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.1.3 Review the current material safety data sheets (MSDS) for detailed information concerning toxicity, first-aid procedures,handling, and safety precautions.1.
5、4 This standard does not purport to address all of the safety problems, 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 precautio
6、nary statements are given in Section 8.2. Referenced Documents2.1 ASTM Standards:2D1193 Specification for Reagent WaterD4672 Test Methods for Polyurethane Raw Materials: Determination of Water Content of PolyolsE180 Practice for Determining the Precision of ASTM Methods for Analysis and Testing of I
7、ndustrial and Specialty ChemicalsE203 Test Method for 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 hy
8、driodic acid. The reaction becomes quantitative only 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 correspon
9、ding to 1 mg of water inaccordance with Faradays law.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 coulo
10、metric technique decreases forconcentrations of water 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 Table 1and Note 6.)5
11、. 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.”35.2 Test Method E203 discusses organic compounds in which water may be determined directly a
12、nd compounds in which water1This test method is under the jurisdiction 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, 2008.2012. Published May 2008.2012. Originally approved in
13、1985. Last previous edition approved in 20052008 as E1064 058. DOI:10.1520/E1064-08.10.1520/E1064-12.2For 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 Doc
14、ument Summary page on the ASTM website.3J. 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 1990.1This document is not an ASTM standard and is intended only to provide the u
15、ser 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 standard
16、as published by ASTM is to be considered the official document.*A Summary of Changes section appears at the end of this standard.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.cannot be determined directly, but in which interferences
17、 may be eliminated by suitable chemical reactions.6. Apparatus6.1 Automatic Titrator,4consisting of a control unit, titration vessel, dual platinum sensing electrode, generator assembly, andmagnetic stirrer. The instrument is designed to coulometrically generate iodine that reacts stoichiometrically
18、 with the water presentin the sample solution. The coulombs of electricity required to generate the reagent are converted to micrograms of water, whichis 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 c
19、hamber.NOTE 1Rinse all glass syringes and needles with anhydrous acetone after cleaning, then dry in an oven at 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 neutrali
20、zing solution into the titrationchamber (see Note 1).6.4 Syringes, 1- and 5-mL, fitted with 115-mm hypodermic needles 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
21、Sealing Grease or TFE-Fluorocarbon, to seal the titration chamber against atmospheric moisture.6.7 Septa, to seal 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 instrum
22、ent drift.6.8 Serum Bottles.6.9 Oven, temperature 100 6 5C.6.10 Dessicator, standard laboratory 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 th
23、e specifications of theCommittee on Analytical Reagents of the American Chemical Society, where such specifications are available.5Other 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 determin
24、ation.7.2 Purity of WaterUnless otherwise indicated, reference to water shall be understood to mean 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 autotitra
25、tors for water determination. Traditionally, pyridine was the organic base used in KF reagents. Pyridine-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 tho
26、se containing pyridine. The use of pyridine-free reagents isrecommended whenever possible. Coulometric titrations normally require two reagent solutions. An anolyte or solvent titrationsolution and a catholyte or generator titrant solution. However, now reagents can be purchased in one or two compon
27、ent 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 HydranaltManual-Eug
28、en 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 o
29、r other organic base and methanol orother alcohol to provide iodine in the reaction mixture.4Basic references to the 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
30、Chemistry 31, No. 2, 215 (1959).5Reagent Chemicals, American Chemical Society Specifications , American Chemical Society, 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
31、., and the United States Pharmacopeia and NationalFormulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville, 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 1227.3.2 S
32、olvent 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 one or more of the following: iodine, pyridine or other organic base, sulfur dioxide, and methanol
33、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 of the reagent with the skin.9. Sampling9.1 Because of the low concentration of water to be measur
34、ed, 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 overnight in an oven at 100C before using. Allow to cool in a desiccator before fillingand sealing.9.1
35、.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 dry nitrogen into thesample bottle with the syringe to displace the sample that is removed.10. Prep
36、aration 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 the chamber from atmospheric moisture. Connect the leads from thesensing and generator electrodes
37、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 (7.3.1) to the generator assembly and replace the cover cap. The surface of the generatorsolution mu
38、st 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 Agitate the titration solution by gently swirling the titration chamber to remove any residual moist
39、ure from the walls.Allowthe solution to stir for at least 20 min to dry and stabilize the inner atmosphere.NOTE 3Mitsubishi automatic moisture 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
40、). 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 inject the neutralizing solution into the titration solution until the color changes from brown to light red. Thisindicates that the end point is near. Contin
41、ue the addition very slowly until the ON light comes on, indicating an excess of wateris present, then carefully withdraw the syringe and needle. 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 Di
42、fferent autotitrators may vary in calibration procedures. Consult the operating manual for the autotitrator in use. Stable,prepackaged Quality 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 calib
43、ration with a standard solution that approximates the same range of waterexpected to be in the samples.11.2 It is recommended that a control chart measuring a QC standard sample be established and maintained according togenerally accepted guidelines.6Measure the control sample each time a test sampl
44、e(s) is tested. If the measured value exceeds 65% of the known amount, take appropriate action before proceeding with the sample test.NOTE 4This may require replacing or regenerating the reagent solutions.12. Procedure12.1 Assemble a dry syringe and needle and attach a small piece of rubber septum t
45、o 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 to 60.1 mg. See Table 1, Note5 and
46、 Note 6.NOTE 5If 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 6Alternatively, if syringes of suitable
47、accuracy are available, a measured volume of sample can be injected and the mass calculated from thevolume and density.6ASTM Manual on Presentation of Data and Control Chart Analysis, 7th Edition, ASTM Manual Series MNL 7A, (revision of Special Technical Publication (STP) 15D).E1064 12312.2 With the
48、 analyzer stabilized, carefully insert the needle of the sample syringe through the septum and below the level ofsolution in the titration chamber. 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 det
49、ermine the exact sample mass. Allow the titration to proceed until theend-point is indicated. Record the micrograms of water determined.NOTE 7After 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 the solution and replace with freshtitration solution if a stable reading cannot be obtained.NOTE 8Replace the generator solution when it becomes yellow and a st
