1、Designation: E 1064 08Standard Test Method forWater in Organic Liquids by Coulometric Karl FischerTitration1This standard is issued under the fixed designation E 1064; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of las
2、t revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) 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 covers the determinat
3、ion of water from0 to 2.0 % mass in most liquid organic chemicals, with KarlFischer reagent, using an automated coulometric titrationprocedure. Use of this test method is not applicable forliquefied gas products such as Liquid Petroleum Gas (LPG),Butane, Propane, Liquid Natural Gas (LNG), etc.1.2 Th
4、e values stated in SI units are to be regarded asstandard. No other units of measurement are included in thisstandard.1.3 Review the current material safety data sheets (MSDS)for detailed information concerning toxicity, first-aid proce-dures, handling, and safety precautions.1.4 This standard does
5、not purport to address all of thesafety problems, if any, associated with its use. It is theresponsibility 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 precau-tionary statements ar
6、e given in Section 8.2. Referenced Documents2.1 ASTM Standards:2D 1193 Specification for Reagent WaterE 180 Practice for Determining the Precision of ASTMMethods for Analysis and Testing of Industrial and Spe-cialty ChemicalsE 203 Test Method for Water Using Volumetric Karl FischerTitration3. Summar
7、y of Test Method3.1 This test method is based on the Karl Fischer reactionfor determining waterthe reduction of iodine by sulfurdioxide in the presence of water to form sulfur trioxide andhydriodic acid. The reaction becomes quantitative only whenpyridine or other organic base and methanol or other
8、alcoholare present. Unlike the volumetric Karl Fischer reagents thatinclude iodine, the coulometric technique electrolytically gen-erates iodine, with 10.71 C of generating current correspondingto 1 mg of water in accordance with Faradays law.4. Significance and Use4.1 The coulometric technique is e
9、specially suited for de-termining low concentrations of water in organic liquids thatwould yield small titers by the Karl Fischer volumetricprocedure. The precision and accuracy of the coulometrictechnique decreases for concentrations of water much greaterthan 2.0 % because of the difficulty in meas
10、uring the small sizeof sample required. The test method assumes 100 % efficiencyof coulombs in iodine production. Provision is made forverifying this efficiency. (See Table 1 and Note 6.)5. Interferences5.1 Interfering substances are the same as are encounteredin the volumetric Karl Fischer titratio
11、n. A detailed discussionof interfering substances can be found in the treatise on“Aquametry.”35.2 Test Method E 203 discusses organic compounds inwhich water may be determined directly and compounds inwhich water cannot be determined directly, but in whichinterferences may be eliminated by suitable
12、chemical reactions.6. Apparatus6.1 Automatic Titrator,4consisting of a control unit, titrationvessel, dual platinum sensing electrode, generator assembly,and magnetic stirrer. The instrument is designed to coulometri-cally generate iodine that reacts stoichiometrically with the1This test method is u
13、nder the jurisdiction of ASTM Committee E15 onIndustrial and Specialty Chemicals and is the direct responsibility of SubcommitteeE15.01 on General Standards.Current edition approved April 1, 2008. Published May 2008. Originallyapproved in 1985. Last previous edition approved in 2005 as E 1064 05.2Fo
14、r referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3J. Mitchell, Jr. and D. M. Smith, “Aquametry”A Treatise on Meth
15、ods for theDetermination of Water, Part IIIThe Karl Fischer Reagent, 2nd Ed., J. Wiley andSons, Inc., New York, NY 1990.4Basic 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.
16、and C. M. Boyd, Analytical Chemistry 31, No. 2, 215 (1959).1*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.water present in the sample solution. The coulombs of elec-t
17、ricity required to generate the reagent are converted tomicrograms of water, which is obtained as a direct digitalreadout.6.2 Syringe, 50-mL, fitted with an 115-mm hypodermicneedle for removing excess solution from the titration chamber.NOTE 1Rinse all glass syringes and needles with anhydrous aceto
18、neafter cleaning, then dry in an oven at 100C for at least 1 h and store ina desiccator. Plastic syringes shall be disposed of following use.6.3 Syringe, 20-mL, fitted with an 115-mm hypodermicneedle for introduction of neutralizing solution into the titrationchamber (see Note 1).6.4 Syringes, 1- an
19、d 5-mL, fitted with 115-mm hypodermicneedles for introduction of samples into titration chamber (seeNote 1).6.5 Syringe, 5 L, fitted with 115-mm hypodermic needlefor standardization of instrument (see Note 1).6.6 Fluorocarbon Sealing Grease or TFE-Fluorocarbon,toseal the titration chamber against at
20、mospheric moisture.6.7 Septa, to seal sample port but allow introduction ofsamples by a needle with a minimum of moisture contamina-tion. Replace serum caps and septa as required to prevent airleakage as indicated by instrument drift.6.8 Serum Bottles.6.9 Oven, temperature 100 6 5C.6.10 Dessicator,
21、standard laboratory type with color changeindicator.6.11 Analytical Balance, capable of weighing to 60.0001 g.7. Reagents7.1 Purity of ReagentsUnless otherwise indicated, it isintended that all reagents shall conform to the specifications ofthe Committee onAnalytical Reagents of theAmerican Chemi-ca
22、l Society, where such specifications are available.5Othergrades may be used, provided it is first ascertained that thereagent is of sufficiently high purity to permit its use withoutlessening the accuracy of the determination.7.2 Purity of WaterUnless otherwise indicated, referenceto water shall be
23、understood to mean Type II or Type IIIreagent water, conforming to Specification D 1193.7.3 Karl Fischer ReagentsCommercial coulometric KFreagents and reagent systems of various types are available foruse with autotitrators for water determination. Traditionally,pyridine was the organic base used in
24、 KF reagents. Pyridine-free formulations are available and are preferred by most KFinstrument manufacturers for use with their equipment. Thepyridine-free reagents are less toxic, less odorous, and morestable than those containing pyridine. The use of pyridine-freereagents is recommended whenever po
25、ssible. Coulometrictitrations normally require two reagent solutions.An anolyte orsolvent titration solution and a catholyte or generator titrantsolution. However, now reagents can be purchased in one ortwo component reagent systems. A one component reagentsystem contains all the components required
26、 for a Karl Fischertitration in a single solution. A two component system incor-porates separate solutions for the solvent and titrant.NOTE 2Two good references on pyridine-free reagents are the Hy-dranaltManual-Eugen Schotz Reagents for Karl Fischer Titration, fromRiedel-deHaen (www.rdhlab.de) or S
27、igma Aldrich (www.sigma-) and Moisture Measurement by Karl Fischer Titrimetry, 2nded., by GFS Chemicals, Inc., January 2004.7.3.1 Generator Titrant Solution (catholyte), containing io-dine, sulfur dioxide, pyridine or other organic base andmethanol or other alcohol to provide iodine in the reactionm
28、ixture.7.3.2 Solvent Titration Solution (anolyte), prepared as perinstrument specifications.7.3.3 Neutralizing Solution, methanol containing approxi-mately 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,
29、andmethanol or other alcohol. Wear chemical resistant gloveswhen mixing the reagents and removing solution from thetitration chamber. Care must be exercised to avoid inhalation ofreagent vapors, or direct contact of the reagent with the skin.9. Sampling9.1 Because of the low concentration of water t
30、o be mea-sured, maximum care must be exercised at all times to avoidcontaminating the sample with moisture from the samplecontainer, the atmosphere, or transfer equipment.9.1.1 Dry the sample bottles and caps overnight in an ovenat 100C before using. Allow to cool in a desiccator beforefilling and s
31、ealing.9.1.2 Fill the sample bottle as rapidly as possible to within25 mm of the top and immediately seal.9.2 Remove the test specimens for analysis from the samplebottle with a dry hypodermic syringe. Inject dry nitrogen intothe sample bottle with the syringe to displace the sample thatis removed.1
32、0. Preparation of Apparatus10.1 Clean, dry, and assemble the titration chamber asdirected in the manufacturers instructions. Use fluorocarbongrease or TFE-fluorocarbon to seal the upper and lowersections of the chamber from atmospheric moisture. Connectthe leads from the sensing and generator electr
33、odes to thetitrator.5Reagent Chemicals, American Chemical Society 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 Uni
34、ted States Pharmacopeiaand National Formulary, 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 0.1E106408210.2 Prepare the titrat
35、ion solution (7.3.2) as directed by theinstrument manufacturer and fill the instrument reservoir asdirected by the manufacturer.10.3 Add the generator solution (7.3.1) to the generatorassembly and replace the cover cap. The surface of thegenerator solution must be below the level of the titrationsol
36、ution to prevent backflow contamination of the titrationsolution. The generator solution may have to be removedperiodically to maintain the lower level.10.4 Agitate the titration solution by gently swirling thetitration chamber to remove any residual moisture from thewalls. Allow the solution to sti
37、r for at least 20 min to dry andstabilize the inner atmosphere.NOTE 3Mitsubishi automatic moisture analyzers do not require thesteps in 10.4.10.5 Attach an 11.5-cm hypodermic needle to a 20-mLsyringe and withdraw about 15 mL of neutralizing solution(7.3.3). Insert the needle through the sample port
38、septum andlower it until the tip is just below the surface of the titrationsolution.10.6 Slowly inject the neutralizing solution into the titrationsolution until the color changes from brown to light red. Thisindicates that the end point is near. Continue the addition veryslowly until the ON light c
39、omes on, indicating an excess ofwater is present, then carefully withdraw the syringe andneedle. The total volume of neutralizing solution required willrange from 5 to 15 mL. Allow the system to stabilize for 1 h.11. Verification of Calibration11.1 Different autotitrators may vary in calibration pro
40、ce-dures. Consult the operating manual for the autotitrator in use.Stable, prepackaged Quality Control (QC) water standards arecommercially available with 10 mg/kg. 100 mg/kg and 1 %(m/m) water content for this purpose. It is desirable to verifycalibration with a standard solution that approximates
41、the samerange of water expected to be in the samples.11.2 It is recommended that a control chart measuring a QCstandard sample be established and maintained according togenerally accepted guidelines.6Measure the control sampleeach time a test sample(s) is tested. If the measured valueexceeds 65 % of
42、 the known amount, take appropriate actionbefore proceeding with the sample test.NOTE 4This may require replacing or regenerating the reagentsolutions.12. Procedure12.1 Assemble a dry syringe and needle and attach a smallpiece of rubber septum to the needle tip. Withdraw 1 to 2 mLof the sample into
43、the syringe and discard the contents into awaste container. Using the following table as a guide, withdrawthe proper amount of test sample into the syringe and seal withthe rubber septum. Obtain a tare weight to 60.1 mg. See Table1, Note 5 and Note 6.NOTE 5If multiple analyses are performed on the s
44、ame test sample orif an appreciable volume of test sample is withdrawn, a slight pressureshould be maintained on the sample bottle by means of a hypodermicneedle attached to a dry nitrogen source.NOTE 6Alternatively, if syringes of suitable accuracy are available, ameasured volume of sample can be i
45、njected and the mass calculated fromthe volume and density.12.2 With the analyzer stabilized, carefully insert the needleof the sample syringe through the septum and below the levelof solution in the titration chamber. Inject the sample slowlyinto the titration solution and begin titration. Withdraw
46、 thesyringe needle, seal and again weigh to the nearest 60.1 mg todetermine the exact sample mass.Allow the titration to proceeduntil the end-point is indicated. Record the micrograms ofwater determined.NOTE 7After numerous analyses, the level of solvent accumulated inthe titration chamber may have
47、to be reduced. This can be accomplishedwith a 50-mL syringe or by partially draining the solution if the titrationchamber is provided with a stopcock. Discard the solution and replacewith fresh titration solution if a stable reading cannot be obtained.NOTE 8Replace the generator solution when it bec
48、omes yellow and astable reading cannot be obtained.13. Calculation13.1 Calculate the water content of the sample to the nearest0.001 % mass as follows:water content, % mass 5g water foundg sample 3 10 000(1)14. Report14.1 Report the percentage of water to the nearest 0.001 %mass.15. Precision and Bi
49、as15.1 In 2007, ASTM International Committee E15 on In-dustrial and Specialty Chemicals conducted and completedInterlaboratory Study No. 52 to determine Precision data forsix test methods used in the analysis of glycols. The precisionof this test method is based on the interlaboratory study ofE 1064, Standard Test Method for the Determination of Waterin Organic Liquids by Coulometric Karl Fischer Titration,conducted in 2007. Each of seventeen laboratories were asked6ASTM Manual on Presentation of Data and Control Chart Analysis, 7thEdition, ASTM Manual
