1、Designation: D 4017 02Standard 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, the year of last r
2、evision. 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 is applicable to all pain
3、ts 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 topigmented products containing amounts of water in the 30 to70 % range, there is reason to believe that high
4、er and lowerconcentrations can be determined by this test method.1.2 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 determine the appl
5、ica-bility of regulatory limitations prior to use. Specific hazardstatements are given in Section 7.2. Referenced Documents2.1 ASTM Standards:D 1193 Specification for Reagent Water2D 3960 Practice for Determining Volatile Organic Com-pound (VOC) Content of Paint and Related Coatings3E 180 Practice f
6、or Determining the Precision of ASTMMethods for Analysis and Testing of Industrial and Spe-cialty Chemicals4E 203 Test Method for Water Using Volumetric Karl FischerTitration42.2 Other Standard:EPA Federal Reference Method 24Determination ofVolatile Matter Content, Density, Volume Solids, andWeight
7、Solids of Surface Coatings53. Summary of Test Method3.1 The material is dissolved 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.
8、1.1 Karl Fischer reagent is a mixture of iodine, amine,sulfur dioxide, and 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 c
9、hemistry that takes place:ROH+SO2+RNa163 (RNH)SO3RH2O+I2+ (RNH)SO3R + 2RN (RNH)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
10、catalyst/buffer. The additionalbuffer capacity is usually already built in to most nonpyridinebased reagents such as hydranal (see Hydranal Manual).64. Significance and Use4.1 Control of water content is often important in control-ling the performance of paint and paint ingredients, and it iscritica
11、l in controlling volatile organic compound (VOC) con-tent.4.2 Paint materials 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 roomtempera
12、ture. 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, manual or au
13、tomatic, encom-passed by the description in Test Method E 203. Apparatusshould be equipped with a 25-mL buret, Class A, or equivalent.5.2 Syringe, 100-L capacity, with needle.5.3 Syringes, 1-mL and 10-mL capacity, without needle, butequipped with caps.1This test method is under the jurisdiction of A
14、STM Committee D01 on Paintand Related Coatings, Materials, and Applications and is the direct responsibility ofSubcommittee D01.21 on Chemical Analysis of Paints and Paint Materials. Currentedition approved Jan. 10, 2002. Published March 2002. Originally published asD 4017 81. Last previous edition
15、D 4017 96a.2Annual Book of ASTM Standards, Vol 11.01.3Annual Book of ASTM Standards, Vol 06.01.4Annual Book of ASTM Standards, Vol 15.05.5Available from the Superintendent of Documents, U.S. Government PrintingOffice, Washington, DC 20402.6Available from Hoechst Celanese Corporation, Hydranal Techni
16、cal Center, U.S.Highway 43, Bucks, AL 36512.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.6. Reagents6.1 Purity of ReagentsReagent grade chemicals shall beused in all tests. Unless otherwise indicated, it is intended thatall reagen
17、ts shall conform to the specifications of the Commit-tee on Analytical Reagents of the American Chemical Society,where such specifications are available.7Other grades may beused, provided it is ascertained that the reagent is of sufficientlyhigh purity to permit its use without lessening the accurac
18、y 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 Karl Fischer Reagent.86.3.1 Nonpyridine Based Karl Fischer Reagent (KFR).6.4 Pyridine.6.5 1-Ethylpiperidi
19、ne.96.6 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 dates on the reagent bottle.7. Hazards7.1 Karl Fischer reagent contains four toxic compounds,namely iodine,
20、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 spillage, wash with large quantities of water.7.2 Treat pyridine and methanol solvents with the same careas K
21、arl 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 the samecare as the chemicals listed in 7.1 and 7.2.8. Procedure8.1 Standardization of Karl Fischer Reagent
22、: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 % of the volume present.8.1.2 Fill the 100-L syringe to about half full with distilledwater and weigh to
23、 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 least 30s.8.1.3.1 The use of the catalyst greatly increases the reactionrate between water and Karl Fische
24、r reagent. To obtain reliableresults, increase the electrode sensitivity and reduce titrationrate to a minimum. Most instruments have controls for thesefunctions. Consult the instructional manual for information onthese controls.8.1.4 Empty the contents of the syringe into the titratorvessel. Immedi
25、ately 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 mean of at least two suchdeterminations. Carry out calculations retaining at least oneextra decimal figure b
26、eyond 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.The value for F should be recorded to the four significant digitsand should be the mean of at least two d
27、eterminations. 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 and catalyst, as described in 8.1.1 and 8.1.3 in thestandardization procedure. Best results are obtained
28、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.NOTE 2Paint samples tend to settle in the syringe and give highpercent water content. Obtain a freshly stirred or mixed specimen for
29、 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 solven
30、t 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 ofsolven
31、t in 8.2.1.7Reagent 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 United States
32、 Pharmacopeiaand National Formulary, U.S. Pharmaceutical Convention, Inc. (USPC), Rockville,MD.8So-K-3 available from Fischer Scientific Co., or equivalent has been foundsuitable for this purpose.9Use 1-ethylpiperidine, manufactured by the Aldrich Chemical Co., Milwaukee,WI 53233, for the best resul
33、ts.TABLE 1 Specimen GuidelinesExpectedwater,%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 401728.2.5 Titrate the specimen slowly with KFR to the end pointdescribed in 8.1.3.8.2.6 Reweigh the emptied
34、 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 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 microbure
35、t 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 measure moisture levels down to 1 ppm(0.0001 %) by this approach.NOTE 3Specimens with less than 0.1 % water may require
36、 specialhandling techniques to prevent pickup of atmospheric moisture. Theprecision of this test method was determined with specimens containinghigher water levels.9. Recommendations for Good Results9.1 Make sure electrodes are clean.9.2 Follow manufacturers instructions to ensure that vent-ing into
37、 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 analyzed. Paints and paint materials are often slow todissolve or disperse. To ensure that all of the water is extractedi
38、nto 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.9.7 Use only Aldrichs 1-ethylpiperidine.6It has been foundthat other brands produce variable results.9.8 For difficu
39、lt-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 titration vessel by rinsing withfresh pyridine. Do not use methanol or other solvents.10.2 DrynessCheck frequently to be
40、 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 response is slug-gish or otherwise off standard, take the following steps, in turn,to correct the problem. Test the ele
41、ctrode 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 concentrated hy-drochloric acid for at least 1 min. Rinse first with distilledwater, then with methanol.10.3.3 Follow manuf
42、acturers instructions on resetting endpoint meter.10.3.4 Replace power source. See manual for replacementprocedure.10.3.5 Replace the electrode.11. Precision and Bias1011.1 The precision estimates are based on an interlaboratorystudy in which one operator in each of seven differentlaboratories analy
43、zed 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 Practice E 180. The within-laboratorycoefficient of variation was found to be 0.9 % relative at 23 df,and the bet
44、ween-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 % confidence level.11.1.1 RepeatabilityTwo results, each the mean of dupli-cate determinations, obtained by the sa
45、me 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, obtained by operators in different labo-ratories should be considered suspect if they differ by morethan 5.5 % relative.1
46、1.2 BiasBias cannot be determined because there are noaccepted standards for water content of paints.12. Keywords12.1 Karl Fischer reagent method; moisture content; watercontent10Supporting data are available from ASTM International Headquarters. RequestRR:D01-1096.D 40173APPENDIXES(Nonmandatory Inf
47、ormation)X1. TEST METHOD FOR KARL FISCHER WATER DETERMINATION FOR LATEX PAINTS USINGEXTRACTION WITH METHANOL11X1.1 ScopeX1.1.1 If variable results are obtained with the pyridinemethod, the methanol extraction method is recommended.X1.1.2 This test method is applicable to paints based onlatex technol
48、ogy, 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 o
49、f the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.X1.2 Referenced DocumentsX1.2.1 ASTM Standards:D 3960 Practice for Determining Volatile Organic Com-pound (VOC) Content of Paints and Related Coatings3E 180 Practice for Determining the Precision of ASTMMethods for Analysis and Testing of Industrial and SpecialtyChemicals4X1.2.2 Other Standard:EPA Reference Method 24, Determination of Volatile MatterContent, Water Content, Density, Volume Solids, and
