1、Designation: D 4017 02 (Reapproved 2008)e1Standard Test Method forWater in Paints and Paint Materials by Karl Fischer Method1This standard is issued under the fixed designation D 4017; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision
2、, 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.e1NOTEThe units statement in subse
3、ction 1.2 was corrected editorially in April 2008.1. Scope1.1 This test method is applicable to all paints and paintmaterials, including resins, monomers, and solvents, with theexception of aldehydes and certain active metals, metal oxides,and metal hydroxides. While the evaluation was limited topig
4、mented products containing amounts of water in the 30 to70 % range, there is reason to believe that higher and lowerconcentrations can be determined by this test method.1.2 The values stated in SI units are to be regarded as thestandard. The values given in parentheses are for informationonly1.3 Thi
5、s 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 health practices and determine the applica-bility of regulatory limitations prior to use. Specific hazardstatem
6、ents are given in Section 7.2. Referenced Documents2.1 ASTM Standards:2D 1193 Specification for Reagent WaterD 3960 Practice for Determining Volatile Organic Com-pound (VOC) Content of Paints and Related CoatingsE 180 Practice for Determining the Precision of ASTMMethods for Analysis and Testing of
7、Industrial and Spe-cialty ChemicalsE 203 Test Method forWater UsingVolumetric Karl FischerTitration2.2 Other Standard:EPA Federal Reference Method 24 Determination of Vola-tile Matter Content, Density, Volume Solids, and WeightSolids of Surface Coatings33. Summary of Test Method3.1 The material is d
8、issolved in a suitable solvent, andtitrated directly with standardized Karl Fischer reagent, to anelectrometric end point. The sluggish reaction with water inpyridine is accelerated with a chemical catalyst,1-ethylpiperidine.3.1.1 Karl Fischer reagent is a mixture of iodine, amine,sulfur dioxide, an
9、d an alcohol. In the reaction with water,iodine is reduced to hydrogen iodide. Once all the water isconsumed, the appearance of free iodine is detected electro-chemically and the titration is stopped. The following depictsthe chemistry that takes place:ROH+SO2+RN (RNH)SO3RH2O+I2+ (RNH)SO3R + 2RN (RN
10、H)SO4R + 2(RNH)I3.2 In classical Karl Fischer titrations the base used ispyridine, and the solvent either methanol or methoxy ethanol.In order to accelerate the reaction when pyridine is used,1-ethylpiperidine is used as a catalyst/buffer. The additionalbuffer capacity is usually already built in to
11、 most nonpyridinebased reagents such as hydranal (see Hydranal Manual).44. Significance and Use4.1 Control of water content is often important in control-ling the performance of paint and paint ingredients, and it iscritical in controlling volatile organic compound (VOC) con-tent.4.2 Paint materials
12、 are often insoluble in common KarlFischer solvents such as methanol. Pyridine has been found tobe a nearly universal solvent for these materials; however, theKarl Fischer reaction is too slow in that solvent at room1This test method is under the jurisdiction of ASTM Committee D01 on Paintand Relate
13、d Coatings, Materials, andApplications and is the direct responsibility ofSubcommittee D01.21 on Chemical Analysis of Paints and Paint Materials.Current edition approved Feb. 1, 2008. Published April 2008. Originallyapproved in 1981. Last previous edition approved in 2002 as D 4017 02.2For reference
14、d 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.3Available from U.S. Government Printing Office Superintendent of Documents
15、,732 N. Capitol St., NW, Mail Stop: SDE, Washington, DC 20401, http:/www.access.gpo.gov.4Available from Hoechst Celanese Corporation, HydranalTechnical Center, U.S.Highway 43, Bucks, AL 36512.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United
16、States.temperature. To speed it up, 1-ethylpiperidine is added at 5 %as a buffer, or “catalyst.”4.3 For nonpyridine-based reagents, a number of differentsolvent systems are available to increase solubility and tominimize interferences from ketones and aldehydes.5. Apparatus5.1 Karl Fischer Apparatus
17、, manual or automatic, encom-passed by the description in Test Method E 203. Apparatusshould be equipped with a 25-mLburet, ClassA, or equivalent.5.2 Syringe, 100-L capacity, with needle.5.3 Syringes, 1-mL and 10-mL capacity, without needle, butequipped with caps.6. Reagents6.1 Purity of ReagentsRea
18、gent 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 available.5Other grades may beused, provided it is a
19、scertained that the reagent is of sufficientlyhigh purity to permit its use without lessening the accuracy ofthe determination.6.2 Purity of WaterUnless otherwise indicated, referencesto water shall be understood to mean reagent grade waterconforming to Type II of Specification D 1193.6.3 Classical
20、Karl Fischer Reagent.66.3.1 Nonpyridine Based Karl Fischer Reagent (KFR).6.4 Pyridine.6.5 1-Ethylpiperidine.76.6 Hydrochloric Acid (HCl), concentrated.NOTE 1All reagents must be fresh. Do not use reagents that are morethan 9 months old. Karl Fischer reagent deteriorates with age. Checkexpiration dat
21、es on the reagent bottle.7. Hazards7.1 Karl Fischer reagent contains four toxic compounds,namely iodine, sulfur dioxide, pyridine, and methanol or glycolether. Prepare and dispense the reagent in a hood. Care must beexercised to avoid inhalation or skin contact. Following acci-dental contact or spil
22、lage, wash with large quantities of water.7.2 Treat pyridine and methanol solvents with the same careas Karl Fischer reagent.7.3 1-ethylpiperidine is of unknown toxicity and, therefore,handle with the same care as the materials listed in 7.1 and 7.2.7.4 Handle also nonpyridine based reagents with th
23、e samecare as the chemicals listed in 7.1 and 7.2.8. Procedure8.1 Standardization of Karl Fischer Reagent:8.1.1 Add enough fresh solvent to cover the electrode tip. Ifusing pyridine, also add 1 mL of 1-ethylpiperidine catalyst per20 mL of pyridine. Catalyst performs best at a concentration ofabout 5
24、 % of the volume present.8.1.2 Fill the 100-L syringe to about half full with distilledwater and weigh to the nearest 0.1 mg.8.1.3 Pretitrate the solvent to the end point indicated by theequipment manufacturer, by adding just enough Karl FischerReagent I (KFR) to cause the end point to hold for at l
25、east 30s.8.1.3.1 The use of the catalyst greatly increases the reactionrate between water and Karl Fischer reagent. To obtain reliableresults, increase the electrode sensitivity and reduce titrationrate to a minimum. Most instruments have controls for thesefunctions. Consult the instructional manual
26、 for information onthese controls.8.1.4 Empty the contents of the syringe into the titratorvessel. Immediately replace the stopper of the sample port andtitrate with KFR to the end point as described in 8.1.3.8.1.5 Repeat standardization until replicate values of Fagree within 1 %. Determine the mea
27、n of at least two suchdeterminations. Carry out calculations retaining at least oneextra decimal figure beyond that of the acquired data. Roundoff figures after final calculations.8.1.6 Calculation:8.1.6.1 Calculate the KFR titre F as follows:F 5 J/P (1)where:J = water added, g, andP = KFR used, mL.
28、The value for F should be recorded to the four significant digitsand should be the mean of at least two determinations. Typicalvalues are in the range of 0.004000 to 0.006000 g/mL.8.2 Analysis of Samples With More Than 0.5 % Water:8.2.1 The titration vessel should already contain pretitratedsolvent
29、and catalyst, as described in 8.1.1 and 8.1.3 in thestandardization procedure. Best results are obtained with freshsolvent, that is, containing no previously titrated specimen inthe vessel.8.2.2 With a 1-mL or 10-mL syringe, draw the amount ofmaterial indicated in Table 1.5Reagent Chemicals, America
30、n 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 United States Pharmacopeiaand National Formulary,
31、U.S. Pharmacopeial Convention, Inc. (USPC), Rockville,MD.6So-K-3 available from Fischer Scientific Co., or equivalent has been foundsuitable for this purpose.7Use 1-ethylpiperidine, manufactured by theAldrich Chemical Co., Milwaukee,WI 53233, for the best results.TABLE 1 Specimen GuidelinesExpectedw
32、ater,%ApproximateSpecimenWeight,gApproximateTitrant Volumeat 5 mg/mLtitre, mL0.51.0 5 51013 25 1020310 12 10201030 0.41.0 20253070 0.10.4 152570 0.1 20D 4017 02 (2008)e12NOTE 2Paint samples tend to settle in the syringe and give highpercent water content. Obtain a freshly stirred or mixed specimen f
33、or eachtest run.8.2.2.1 Remove the syringe from the specimen, pull theplunger out a little further, wipe the excess material off thesyringe, and place a cap on the syringe tip. Weigh the filledsyringe to the nearest 0.1 mg.8.2.3 Remove the cap, and empty the syringe contents intothe pretitrated solv
34、ent vessel. Pull the plunger out and replacethe cap.8.2.4 Stir rapidly for 1 to 2 min before starting titration.Some instruments can be set to do this automatically. If thespecimen is still not dissolved or dispersed, continue stirringuntil it is dissolved, or use a different solvent in place ofsolv
35、ent in 8.2.1.8.2.5 Titrate the specimen slowly with KFR to the end pointdescribed in 8.1.3.8.2.6 Reweigh the emptied syringe, and calculate the speci-men weight by difference.8.2.7 Calculation:8.2.7.1 Calculate the percent water L as follows:L 5 P 3 F 3 100!/S (2)8.3 Analysis of Materials With Less
36、Than 0.5 % Water:8.3.1 For 0.1 to 0.5 %, follow procedure in 8.2 (1-g speci-men), except substitute a 1-mL microburet for the 25-mL buretin the Karl Fischer apparatus.8.3.2 For less than 0.1 %, use a 1-mL microburet andincrease specimen size as much as needed, up to 10 g. It shouldbe possible to mea
37、sure moisture levels down to 1 ppm(0.0001 %) by this approach.NOTE 3Specimens with less than 0.1 % water may require specialhandling techniques to prevent pickup of atmospheric moisture. Theprecision of this test method was determined with specimens containinghigher water levels.9. Recommendations f
38、or Good Results9.1 Make sure electrodes are clean.9.2 Follow manufacturers instructions to ensure that vent-ing into the titration vessel is only through a dessicant.9.3 Samples should be thoroughly mixed before taking aspecimen.9.4 Use an appropriate solvent/reagent for the paint/coatingbeing analy
39、zed. Paints and paint materials are often slow todissolve or disperse. To ensure that all of the water is extractedinto the pyridine or solvent, stir rapidly for 1 or 2 min beforestarting the titration.9.5 Run the titration slowly with rapid stirring.9.6 Throw out the first result in fresh pyridine.
40、9.7 Use onlyAldrichs 1-ethylpiperidine.4It has been foundthat other brands produce variable results.9.8 For difficult-to-dissolve samples, extract the water witha suitable solvent, such as dry methanol. An example of thisprocedure is outlined in Appendix X1.10. Maintenance10.1 CleanupClean the titra
41、tion vessel by rinsing withfresh pyridine. Do not use methanol or other solvents.10.2 DrynessCheck frequently to be sure that all dryingtubes are in good condition and tightly connected. Replacedessicant when indicator color changes through half of thetube.10.3 Electrode PerformanceIf electrode resp
42、onse is slug-gish or otherwise off standard, take the following steps, in turn,to correct the problem. Test the electrode with a titration aftereach step, to determine if the next step is required.10.3.1 Wipe the electrode tip with a clean paper towel.10.3.2 Wash the electrode by dipping in concentr
43、ated hy-drochloric acid for at least 1 min. Rinse first with distilledwater, then with methanol.10.3.3 Follow manufacturers instructions on resetting endpoint meter.10.3.4 Replace power source. See manual for replacementprocedure.10.3.5 Replace the electrode.11. Precision and Bias811.1 The precision
44、 estimates are based on an interlaboratorystudy in which one operator in each of seven differentlaboratories analyzed in duplicate on two different days sevensamples of water-based paints of various types containingbetween 25 to 75 % water. The results were analyzed statisti-cally in accordance with
45、 Practice E 180. The within-laboratorycoefficient of variation was found to be 0.9 % relative at 23 df,and the between-laboratory coefficient of variation was 1.9 %relative, at 18 df. Based on these coefficients, the followingcriteria should be used for judging the acceptability of resultsat the 95
46、% confidence level.11.1.1 RepeatabilityTwo results, each the mean of dupli-cate determinations, obtained by the same operator on differentdays should be considered suspect if they differ by more than3.5 % relative.11.1.2 ReproducibilityTwo results, each the mean of du-plicate determinations, obtaine
47、d by operators in different labo-ratories should be considered suspect if they differ by morethan 5.5 % relative.11.2 BiasBias cannot be determined because there are noaccepted standards for water content of paints.12. Keywords12.1 Karl Fischer reagent method; moisture content; watercontent8Supporti
48、ng data have been filed at ASTM International Headquarters and maybe obtained by requesting Research Report RR:D01-1096.D 4017 02 (2008)e13APPENDIXES(Nonmandatory Information)X1. TEST METHOD FOR KARL FISCHER WATER DETERMINATION FOR LATEX PAINTS USINGEXTRACTION WITH METHANOL9X1.1 ScopeX1.1.1 If varia
49、ble results are obtained with the pyridinemethod, the methanol extraction method is recommended.X1.1.2 This test method is applicable to paints based onlatex technology, which may not be sufficiently soluble in thesolvents specified in the direct titration method. Some solvent-based paints will“ ball up” in contact with methanol.X1.1.3 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 health practices and de
