1、Designation: E 1064 05Standard 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. Scope1.1 This test method covers the determinati
3、on 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 The
4、 values stated in SI units are to be regarded as thestandard.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 not purport to address all of thesafety problems, if any,
5、 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 are given in Section 8.2. Referenced Documents2.1 ASTM Stan
6、dards:2D 1193 Specifications for Reagent WaterD 4672 Test Methods for Polyurethane Raw Materials:Determination of Water Content of PolyolsE 180 Practice for Determining the Precision of ASTMMethods for Analysis and Testing of Industrial and Spe-cialty ChemicalsE 203 Test Method for Water Using Volum
7、etric Karl FischerTitration3. Summary 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
8、 organic base and methanol or other 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 U
9、se4.1 The coulometric technique is especially 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
10、 % because of the difficulty in measuring 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.)1This test method is under the jurisdiction of ASTM Committee E15 onIndustria
11、l and Specialty Chemicals and is the direct responsibility of SubcommitteeE15.01 on General Standards.Current edition approved Oct. 1, 2005. Published November 2005. Originallyapproved in 1985. Last previous edition approved in 2004 as E 1064 04a.2For referenced ASTM standards, visit the ASTM websit
12、e, 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.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States
13、.5. Interferences5.1 Interfering substances are the same as are encounteredin the volumetric Karl Fischer titration. 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 a
14、nd compounds inwhich water cannot be determined directly, but in whichinterferences may be eliminated by suitable chemical reactions.6. Apparatus6.1 Automatic Titrator,4consisting of a control unit, titrationvessel, dual platinum sensing electrode, generator assembly,and magnetic stirrer. The instru
15、ment is designed to coulometri-cally generate iodine that reacts stoichiometrically with thewater present in the sample solution. The coulombs of elec-tricity required to generate the reagent are converted tomicrograms of water, which is obtained as a direct digitalreadout.6.2 Syringe, 50-mL, fitted
16、 with an 115-mm hypodermicneedle for removing excess solution from the titration chamber.NOTE 1Rinse all glass syringes and needles with anhydrous acetoneafter 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 Syr
17、inge, 20-mL, fitted with an 115-mm hypodermicneedle for introduction of neutralizing solution into the titrationchamber (see Note 1).6.4 Syringes, 1- and 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 hyp
18、odermic needlefor standardization of instrument (see Note 1).6.6 Fluorocarbon Sealing Grease or TFE-Fluorocarbon,toseal the titration chamber against atmospheric moisture.6.7 Septa, to seal sample port but allow introduction ofsamples by a needle with a minimum of moisture contamina-tion. Replace se
19、rum 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, standard laboratory type with color changeindicator.6.11 Analytical Balance, capable of weighing to 60.0001 g.7. Reagents7.1 Purity of ReagentsUnles
20、s otherwise indicated, it isintended that all reagents shall conform to the specifications ofthe Committee onAnalytical Reagents of theAmerican Chemi-cal Society, where such specifications are available.5Othergrades may be used, provided it is first ascertained that thereagent is of sufficiently hig
21、h purity to permit its use withoutlessening the accuracy of the determination.7.2 Purity of WaterUnless otherwise indicated, referenceto water shall be understood to mean Type II or Type IIIreagent water, conforming to Specification D 1193.7.3 Karl Fischer ReagentsCommercial coulometric KFreagents a
22、nd reagent systems of various types are available foruse with autotitrators for water determination. Traditionally,pyridine was the organic base used in KF reagents. Pyridine-free formulations are available and are preferred by most KFinstrument manufacturers for use with their equipment. Thepyridin
23、e-free reagents are less toxic, less odorous, and morestable than those containing pyridine. The use of pyridine-freereagents is recommended whenever possible. Coulometrictitrations normally require two reagent solutions.An anolyte orsolvent titration solution and a catholyte or generator titrantsol
24、ution. However, now reagents can be purchased in one ortwo component reagent systems. A one component reagentsystem contains all the components required for a Karl Fischertitration in a single solution. A two component system incor-porates separate solutions for the solvent and titrant.NOTE 2Two goo
25、d references on pyridine-free reagents are the Hy-dranaltManual-Eugen Schotz Reagents for Karl Fischer Titration, fromRiedel-deHaen (www.rdhlab.de) or Sigma Aldrich (www.sigma-) and Moisture Measurement by Karl Fischer Titrimetry, 2nded., by GFS Chemicals, Inc., January 2004.7.3.1 Generator Titrant
26、Solution (catholyte), containing io-dine, sulfur dioxide, pyridine or other organic base andmethanol or other alcohol to provide iodine in the reactionmixture.7.3.2 Solvent Titration Solution (anolyte), prepared as perinstrument specifications.7.3.3 Neutralizing Solution, methanol containing approxi
27、-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, andmethanol or other alcohol. Wear chemical resistant gloveswhen mixing the reagents and removing solution from thetitration chamber. Care must be e
28、xercised to avoid inhalation ofreagent vapors, or direct contact of the reagent with the skin.9. Sampling9.1 Because of the low concentration of water to be mea-sured, maximum care must be exercised at all times to avoid3J. Mitchell, Jr. and D. M. Smith, “Aquametry”A Treatise on Methods for theDeter
29、mination 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. and C. M. Boyd,
30、Analytical Chemistry 31, No. 2, 215 (1959).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, Dor
31、set, U.K., and the United 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 0.1E1064052c
32、ontaminating 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 sealing.9.1.2 Fill the sample bottle as rapidly as possible to within2
33、5 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.10. Preparation of Apparatus10.1 Clean, dry, and assemble the titratio
34、n 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 electrodes to thetitrator.10.2 Prepare the titration solution (7.3.2) as di
35、rected 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 titrationsolution to prevent backflow
36、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 stir for at least 20 min to d
37、ry 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 septum andlower it until t
38、he 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 comes on, indicating an exc
39、ess 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 proce-dures. Consult the oper
40、ating 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 the samerange of water exp
41、ected 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 the known amount, take ap
42、propriate 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 the syringe and discard th
43、e 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 same test sample orif an ap
44、preciable 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 injected and the mass calcu
45、lated 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 thesyringe needle, seal a
46、nd 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 to be reduced. This can be
47、 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 becomes yellow and astable re
48、ading 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 Bias15.1 PrecisionThe follow
49、ing criteria should be used tojudge the acceptability of results when using pyridine-basedreagents (see Note 9):15.1.1 Repeatability (Single Analyst)The coefficient ofvariation for a single determination has been estimated to be6ASTM Manual on Presentation of Data and Control Chart Analysis, 7thEdition, ASTM Manual Series MNL 7A, (revision of Special Technical Publication(STP) 15D).E10640531.39 % relative at 61 DF. The 95 % limit for the differencebetween two such runs is 3.9 % relative.15.1.2 Laboratory Precision (Within-Laboratory, BetweenDays Vari
