1、Designation: D1364 02 (Reapproved 2012)Standard Test Method forWater in Volatile Solvents (Karl Fischer Reagent TitrationMethod)1This standard is issued under the fixed designation D1364; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revis
2、ion, 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 co
3、vers 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 conforma
4、nce 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 E29.1.4 The values stated
5、 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 and h
6、ealth 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:2D1500 Test Method for ASTM Color of Petroleum Products(ASTM Color Scale)E29 Practice
7、 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 impressed
8、, 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, nDuring
9、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.NOTE 2Vie
10、w 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 D1500.4. Summary of Test Method4.1 This test method is based essentially upon the reductionof iodine by sulfur dioxide in the presenc
11、e 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:H2O1I21SO213C5H5N2C5H5NHI1C5H5NSO3(1)C5H5NSO31ROHC5H5NHSO4R4.2 To determine water, Karl Fischer reagent (
12、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. Thisis evidenced by the persistence of the orange-re
13、d end-pointcolor; or alternatively by an indication on a galvanometer orsimilar current-indicating device which records the depolariza-tion of a pair of noble-metal electrodes. The reagent isstandardized by titration of water.1This test method is under the jurisdiction of ASTM Committee D01 on Paint
14、and Related Coatings, Materials, andApplications and is the direct responsibility ofSubcommittee D01.35 on Solvents, Plasticizers, and Chemical Intermediates.Current edition approved July 1, 2012. Published September 2012. Originallyapproved in 1955. Last previous edition approved in 2007 as D1364 0
15、2 (2007).DOI: 10.1520/D1364-02R12.2For 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.*A Summary of Changes secti
16、on appears at the end of this standardCopyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States15. Significance and Use5.1 Volatile solvents are used in a variety of chemicalprocesses which may be affected by water. Therefore, this testmethod p
17、rovides a test procedure 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
18、 end point and isparticularly 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 s
19、tirrer, and a meansof 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 s
20、o inserted in the 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 20
21、A by means of a galvanometer 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 w
22、hen exposed to moist 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
23、 Grethen Type, orequivalent.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 specifi
24、cations are available.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
25、6 1gofI2in4256 2 mL of anhydrous (less than 0.1 % H2O) pyridine in adry glass-stoppered bottle.Add 425 6 2 mLof 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 SO2add
26、ed by measuring the 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.7.1.2 Solvent MixtureMix 1 volume of anhydrous (lessthan 0.1 % H2O) pyridine with 4 volumes of anhydr
27、ous (lessthan 0.1 % H2O) ethylene glycol.3The sole source of supply of flasks known to the committee at this time is theRankin Glass Blowing Co., 3920 Franklin Canyon Road, Martinez, CA. If you areaware of alternative suppliers, please provide this information to ASTM Interna-tional Headquarters. Yo
28、ur comments will receive careful consideration at a meetingof the responsible technical committee,1which you may attend.4The sole source of supply of instrument depolarization indicator known to thecommittee at this time is Fisher Scientific Co. (need address). If you are aware ofalternative supplie
29、rs, please provide this information to ASTM InternationalHeadquarters. Your comments will receive careful consideration at a meeting of theresponsible technical committee,1which you may attend.5The sole source of supply of automatic dispensing burets, No. J-821, known tothe committee at this time is
30、 Scientifice glass Apparatus Co., Bloomfield NJ. If youare aware of alternative suppliers, please provide this information to ASTMInternational Headquarters. Your comments will receive careful consideration at ameeting of the responsible technical committee,1which you may attend. Thesespecifically d
31、esigned burets present the minimum contact of reagent with stopcocklubricant.6Reagent 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 Laborat
32、oryChemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeiaand National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville,MD.7Karl Fischer Reagent is available from various laboratory suppliers. Pyridine-free adaptations are available and may be used if precision c
33、an be established. If youare aware of alternative suppliers, please provide this information to ASTMInternational Headquarters. Your comments will receive careful consideration at ameeting of the responsible technical committee,1which you may attend.NOTE 1All dimensions in millimetres.FIG. 1 Titrati
34、on Flask AssemblyD1364 02 (2012)2NOTE 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 thef
35、irst 5 % of material 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 % distille
36、d is discarded and 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 sourcea
37、re particularly 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. Standardi
38、zation of Reagent9.1 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
39、. Add to thesolvent 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
40、content per millilitre 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 (pyridi
41、ne-glycol, 1 + 4) 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 mixingwith
42、out splashing. Titrate 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
43、standard fortitrating 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 Ka
44、rl Fischer reagent 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
45、 reagent.(b) Organic 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 t
46、ip. In less humid 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
47、 titration is interrupted, 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 wate
48、r content of the specimen as follows:Water, %, by weight 5 V 3W!/10 3S! (3)where:V = volume of Karl Fischer reagent required for titrating bythe specimen, mL,W = equivalency factor for Karl Fischer reagent, water permillilitre of reagent, mg, andS = specimen weight used, g.NOTE 8If specimen was adde
49、d volumetrically by means of acalibrated volumetric pipet, then S = volume of specimen 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 containing0.1
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