1、Designation: D 1364 02 (Reapproved 2007)Standard Test Method forWater in Volatile Solvents (Karl Fischer Reagent TitrationMethod)1This standard is issued under the fixed designation D 1364; the number immediately following the designation indicates the year oforiginal adoption or, in the case of rev
2、ision, the year of last 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
3、 covers the determination of water involatile solvents and chemical intermediates used in paint,varnish, lacquer, and related products.1.2 This test method is not applicable in the presence ofmercaptans, peroxides, or appreciable quantities of aldehydesor amines.1.3 For purposes of determining confo
4、rmance of an ob-served or a calculated value using this test method to relevantspecifications, test result(s) shall be rounded off “to the nearestunit” in the last right-hand digit used in expressing thespecification limit, in accordance with the rounding-off methodof Practice E 29.1.4 The values st
5、ated in SI units are to be regarded asstandard. No other units of measurement are included in thisstandard.1.5 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety a
6、nd health practices and determine the applica-bility of regulatory limitations prior to use.1.6 For hazard information and guidance, see the suppliersMaterial Safety Data sheet.2. Referenced Documents2.1 ASTM Standards:2D 1500 Test Method for ASTM Color of Petroleum Prod-ucts (ASTM Color Scale)E29 P
7、ractice for Using Significant Digits in Test Data toDetermine Conformance with Specifications3. Terminology3.1 Definitions of Terms Specific to This Standard:3.1.1 instrumental end point, nthat point in the titrationwhen two small platinum electrodes, upon which a potential of20 to 50 mV has been im
8、pressed, are depolarized by theaddition of 0.05 mL of Karl Fischer reagent (6 mg of H2O permL), causing a change of current flow of 10 to 20 A thatpersists for at least 30 s.NOTE 1This end point is sometimes incorrectly called the “dead stop”which is the reverse of the above.3.1.2 color end point, n
9、During the titration, the solutionfirst turns yellow, then later deepens towards the end of thetitration; the end point is indicated by the change from yellowto orange-red which is quite sharp and easily repeated. Theorange-red color must persist for at least 30 s in order toindicate an end point.NO
10、TE 2View the color by transmitted daylight or by transmitted lightfrom an artificial daylight lamp, such as the one that complies with thespecifications given in Test Method D 1500.4. Summary of Test Method4.1 This test method is based essentially upon the reductionof iodine by sulfur dioxide in the
11、 presence of water. Thisreaction can be used quantitatively only when pyridine and analcohol are present to react with the sulfur trioxide andhydriodic acid produced according to the following reactions:H2O 1 I21 SO21 3C5H5N2C5H5NHI 1 C5H5NSO3C5H5NSO31 ROHC5H5NHSO4R(1)4.2 To determine water, Karl Fi
12、scher reagent (a solution ofiodine, pyridine, and sulfur dioxide, in the molar ratio of1 + 10 + 3) dissolved in anhydrous 2-methoxyethanol is addedto a solution of the sample in anhydrous pyridine-ethyleneglycol (1 + 4) until all water present has been consumed. This1This test method is under the ju
13、risdiction of ASTM Committee D01 on Paintand Related Coatings, Materials, and Applications and is the direct responsibility ofSubcommittee D01.35 on Solvents, Plasticizers, and Chemical Intermediates.Current edition approved June 1, 2007. Published June 2007. Originallyapproved in 1955. Last previou
14、s edition approved in 2002 as D 1364 02.2For 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.1*A Summary of Change
15、s 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.is evidenced by the persistence of the orange-red end-pointcolor; or alternatively by an indication on a galvanometer orsimilar current-indi
16、cating device which records the depolariza-tion of a pair of noble-metal electrodes. The reagent isstandardized by titration of water.5. Significance and Use5.1 Volatile solvents are used in a variety of chemicalprocesses which may be affected by water. Therefore, this testmethod provides a test pro
17、cedure for assessing compliancewith a specification.6. Apparatus6.1 Titration VesselFor color end point titrations, use a100 or 250-mL volumetric flask, which need not be calibrated;a 250-mL flask fitted with interchangeable electrodes (Fig. 1)3may also be used for the instrumental end point and isp
18、articularly suitable for titrations at ice temperatures. Forpermanently mounted assemblies, the vessel should have acapacity about equal to that of a 300-mL tall-form beaker; andbe provided with a tight-fitting closure to protect the sampleand reagent from atmospheric moisture, a stirrer, and a mean
19、sof adding sample and reagents and removing spent reactionmixture. It is desirable to have a means for cooling the titrationvessel to ice temperature.6.2 Instrument ElectrodesPlatinum with a surface equiva-lent to two No. 26 wires 5 mm long. The wires should be 3 to8 mm apart and so inserted in the
20、vessel that 25 mL of liquidwill cover them.6.3 Instrument Depolarization Indicator, having an internalresistance of less than 5000 V and consisting of a means ofimpressing and showing a voltage of 20 to 50 mV across theelectrodes and capable of indicating a current flow of 10 to 20A by means of a ga
21、lvanometer or radiotuning eye circuit.46.4 Buret Assembly for Karl Fischer reagent, consisting of a25 or 50-mL buret connected by means of glass (not rubber)connectors to a source of reagent; several types of automaticdispensing burets5may be used. Since the reagent losesstrength when exposed to moi
22、st air, all vents must be protectedagainst atmospheric moisture by adequate drying tubes con-taining indicating calcium sulfate drying agent. All stopcocksand joints should be lubricated with a lubricant not particularlyreactive with the reagent.6.5 Weighing Bottle, of the Lunge or Grethen Type, ore
23、quivalent.7. Reagents7.1 Purity of ReagentsReagent grade chemicals shall beused in all tests. Unless otherwise indicated, it is intended thatall reagents shall conform to the specifications of the Commit-tee on Analytical Reagents of the American Chemical Society,where such specifications are availa
24、ble.6Other grades may beused, provided it is first ascertained that the reagent is ofsufficiently high purity to permit its use without decreasing theaccuracy of the determination.7.1.1 Karl Fischer Reagent (equivalent to 6 mg of H2O permL)7For each liter of solution, dissolve 133 6 1gofI2in4256 2 m
25、L of anhydrous (less than 0.1 % H2O) pyridine in adry glass-stoppered bottle.Add 425 6 2 mL of anhydrous (lessthan 0.1 % H2O) 2-methoxyethanol. Cool to below 4C in anice bath and add gaseous SO2, dried by bubbling throughconcentrated H2SO4(sp gr 1.84); determine the amount of SO2added by measuring t
26、he change in weight of the SO2cylinder(102 6 1 g) or the increase in volume (70 6 1 mL) of thereagent mixture. Alternatively, add 70 mL of freshly drawnliquid SO2in small increments.3The sole source of supply of flasks known to the committee at this time is theRankin Glass Blowing Co., 3920 Franklin
27、 Canyon Road, Martinez, CA. If you areaware of alternative suppliers, please provide this information to ASTM Interna-tional Headquarters. Your comments will receive careful consideration at a meetingof the responsible technical committee,1which you may attend.4The sole source of supply of instrumen
28、t depolarization indicator known to thecommittee at this time is Fisher Scientific Co. (need address). If you are aware ofalternative suppliers, please provide this information to ASTM InternationalHeadquarters. Your comments will receive careful consideration at a meeting of theresponsible technica
29、l committee,1which you may attend.5The sole source of supply of automatic dispensing burets, No. J-821, known tothe committee at this time is Scientifice glass Apparatus Co., Bloomfield NJ. If youare aware of alternative suppliers, please provide this information to ASTMInternational Headquarters. Y
30、our comments will receive careful consideration at ameeting of the responsible technical committee,1which you may attend. Thesespecifically designed burets present the minimum contact of reagent with stopcocklubricant.6Reagent Chemicals, American Chemical Society Specifications, AmericanChemical Soc
31、iety, 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. Pharmacopeial Convention, Inc. (USPC), Rockville,MD
32、.7Karl Fischer Reagent is available from various laboratory suppliers. Pyridine-free adaptations are available and may be used if precision can be established. If youare aware of alternative suppliers, please provide this information to ASTMInternational Headquarters. Your comments will receive care
33、ful consideration at ameeting of the responsible technical committee,1which you may attend.NOTE 1All dimensions in millimetres.FIG. 1 Titration Flask AssemblyD 1364 02 (2007)27.1.2 Solvent MixtureMix 1 volume of anhydrous (lessthan 0.1 % H2O) pyridine with 4 volumes of anhydrous (lessthan 0.1 % H2O)
34、 ethylene glycol.NOTE 3Pyridine, ethylene glycol, and 2-methoxyethanol, each con-taining less than 0.1 % water, are available and should be used.NOTE 4If adequately dry reagents cannot be procured, they can eachbe dried by distillation through a multiple-plate column, discarding thefirst 5 % of mate
35、rial distilling overhead and using the 95 % remaining.Drying may also be accomplished by the addition of 1 volume of tolueneor cyclohexane to 19 volumes of the pyridine-glycol, or of the pyridineethylene glycol monomethyl ether mixture, followed by distillation; thefirst 5 % distilled is discarded a
36、nd the residual 95 % is used.8. Sampling8.1 Hygroscopic Solvents, including for example, ketones,acetates, alcohols, and glycol ethers, absorb ambient moisture.It is essential to avoid changes in the water content of thesematerials during sampling operations. Errors from this sourceare particularly
37、significant in the analysis of materials havinglow water content. When analyzing materials that absorbambient water readily, limit as much as possible contact withair in transferring the specimen into the titration vessel. Avoidintermediate sample containers, if possible.9. Standardization of Reagen
38、t9.1 Standardize the Karl Fischer reagent each day used byeither the color or instrument end point (Section 3) methodusing the same procedure as used for titrating the sample.9.1.1 Add to each flask 25 mL of ethylene glycol-pyridenemixture, and titrate this as described in Section 10. Add to thesolv
39、ent thus titrated, in place of the sample, 0.15 to 0.18 g ofwater from a weighing bottle or weighing pipet, weighed to thenearest 0.1 mg. Complete titration with Karl Fischer reagent asdescribed in Section 10.9.1.2 Calculate the equivalency factor, W, of the reagent interms of water content per mill
40、ilitre by means of the followingequation:W 5 A/V (2)where:W = equivalency factor, mg of water per mL,A = weight of water used in the standardization, mg, andV = volume of Karl Fischer reagent required, mL.10. Procedure10.1 Introduce 10 to 25 mL of the anhydrous solventmixture (pyridine-glycol, 1 + 4
41、) into the titration vessel, mak-ing sure, if an instrument end point apparatus is used, that theelectrodes are covered by this amount of solvent. If the colorend point is to be determined, make up a second flask as well.10.2 Adjust the stirrer, if any, to provide adequate mixingwithout splashing. T
42、itrate the mixture to the instrumental endpoint (see 3.1), or the color end point (see 3.1.2), with KarlFischer reagent. If the color end point is to be observed, titrateone flask to the orange-red end point and the second to matchthe first. Set aside the first flask as a comparison standard fortitr
43、ating the specimen.10.3 To the titration mixture thus prepared, add an amountof specimen as indicated in Table 1. Exercise care when thespecimen is transferred so that water is not absorbed from theair, particularly under conditions of high humidity. Again,titrate the mixture with Karl Fischer reage
44、nt to the sameinstrumental or color end point previously employed. Recordthe amount of reagent used to titrate the water in the specimen.NOTE 5(a) KetonesIn titrating ketones when greatest precision isrequired, cool the reaction mixture in ice water during the addition of KarlFischer reagent.(b) Org
45、anic AcidsCool the reaction mixture in ice water prior to theaddition of Karl Fischer reagent.NOTE 6When using the volumetric flask type titration vessel in humidclimates, place a piece of thin sheet rubber over the mouth of the vessel;provide a small hole for introducing the buret tip. In less humi
46、d climatesit is sufficient to lower the tip of the buret deeply into the long neck of thetitration flask.NOTE 7In titrating with the volumetric flask type titration vessel,avoid wetting the stopper and upper end of the flask with either the reagentor the sample solvent. Each time the titration is in
47、terrupted, touch the burettip to the neck of the flask to remove droplets which, if not removed,would absorb moisture from the atmosphere. When the flask is removedfrom under the buret tip, wipe the tip with a clean dry cloth in a downwardmotion.11. Calculation11.1 Calculate the water content of the
48、 specimen as follows:Water, %, by weight 5 V 3 W!/10 3 S! (3)where:V = volume of Karl Fischer reagent required for titratingby the specimen, mL,W = equivalency factor for Karl Fischer reagent, water permillilitre of reagent, mg, andS = specimen weight used, g.NOTE 8If specimen was added volumetrical
49、ly by means of a cali-brated volumetric pipet, then S = volume of specimen 3 density ofspecimen, g.12. Report12.1 For water concentrations below 0.5 %, report all re-sults to 0.001 %. Two determinations which agree within0.008 %, absolute, are acceptable for averaging (95 % confi-dence level).13. Precision and Bias13.1 Precision for Water 0.100 to 0.500 % by WeightOnthe basis of an interlaboratory study in which one operatormade duplicate determinations in each of eight differentlaboratories, on two days, on samples of acetone containing0.118 and 0.406
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