1、Designation: D 1123 99 (Reapproved 2003)e1Standard Test Methods forWater in Engine Coolant Concentrate by the Karl FischerReagent Method1This standard is issued under the fixed designation D 1123; the number immediately following the designation indicates the year oforiginal adoption or, in the case
2、 of revision, 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.e1NOTEDefinitions, 3.1
3、, was changed to Descriptions of Terms editorially in April 2007.1. Scope1.1 These test methods cover the determination of the waterpresent in new or unused glycol-based coolant concentratesusing a manual (Test Method A) or an automatic (Test MethodB) coulometric titrator procedure.1.2 Many carbonyl
4、 compounds react slowly with the Fis-cher reagent, causing a fading end point and leading to highresults. A modified Fischer reagent procedure is included thatminimizes these undesirable and interfering reactions.1.3 This standard does not purport to address all of thesafety problems, if any, associ
5、ated 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. For specific hazardsstatements see Sections 8 and 16.2. Referenced Documents2.1 ASTM Standards:2D 156
6、 Test Method for Saybolt Color of Petroleum Prod-ucts (Saybolt Chromometer Method)D 1176 Practice for Sampling and Preparing Aqueous So-lutions of Engine Coolants or Antirusts for Testing Pur-posesD 1193 Specification for Reagent WaterE 203 Test Method for Water Using Volumetric Karl FischerTitratio
7、n3. Terminology3.1 Definitions of Terms Specific to This Standard:3.1.1 color end pointthat point during the titration whenthe color change from yellow to orange-red is sharp and easilyrepeated. The orange-red color must persist for at least 30 s inorder to indicate an end point.3.1.1.1 DiscussionVi
8、ew the color by transmitted daylightor by transmitted light from an artificial daylight lamp, such asone that complies with the specification given in Test MethodD 156.3.1.2 instrument end pointfor the purpose of these tests,that point in the titration when two small platinum electrodes,upon which a
9、 potential of 20 to 50 mV has been impressed, aredepolarized by the addition of 0.05 mL of Fischer reagent (6mg of water/mL), causing a change of current flow of 10 to 20A that persists for at least 30 s.3.1.2.1 DiscussionThis end point is sometimes incor-rectly called the “dead stop,” which is the
10、reverse of the above.4. Summary of Test Methods4.1 These test methods are based essentially on the reduc-tion of iodine by sulfur dioxide in the presence of water. Thisreaction can be used quantitatively only when pyridine and analcohol are present to react as follows:I21 SO21 H2OSO31 2HI (1)4.2 In
11、order to determine water, Karl Fischer reagent isadded to a solution of the sample in anhydrous high-puritymethanol until all water present has been consumed. This isevidenced by the persistence of the orange-red end point color,or alternatively by an indication on a galvanometer or similarcurrent-i
12、ndicating device that records the depolarization of apair of noble metal electrodes. The reagent is standardized bythe titration of water.NOTE 1It is believed that these methods give all the informationrequired for determining the water in coolant formulations. Shouldadditional information on water
13、determinations be needed, referenceshould be made to Test Method E 203.5. Significance and Use5.1 The total apparent water in engine coolant concentrateas determined by Karl Fischer titrations consists of the fol-lowing: (1) water present in the original glycol base; (2) wateradded (for example, inh
14、ibitor solutions); (3) water of hydrationof inhibitors (for example, Na2B4O75H2O); ( 4) water formed1These test methods are under the jurisdiction of ASTM Committee D15 onEngine Coolants and are the direct responsibility of Subcommittee D15.04 onChemical Properties.Current edition approved May 10, 1
15、999. Published August 1999. Originallypublished as D 1123 50. Last previous edition D 1123 93.2Annual Book of ASTM Standards, Vol 05.01.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.in the chemical reaction between borate and ethyl
16、ene glycol,producing boratediol condensate and water; and ( 5) quantita-tive interference by the reaction of the reagent with inhibitorssuch as tetraborate or sodium hydroxide.TEST METHOD AMANUAL TITRATION6. Apparatus6.1 Titration Vessel For color end point titrations, use a100 or 250-mL volumetric
17、flask, which need not be calibrated.For instrument end point, a 250-mL flask fitted with inter-changeable electrodes (Fig. 1)3may be used. This is particu-larly good for titrations of coolant concentrate that is deeplycolored from dye or any other cause. For permanently mountedassemblies, the vessel
18、 should have a capacity about equal tothat of a 300-mL tall-form beaker and should be provided witha tight-fitting closure to protect the sample and reagent fromatmospheric moisture, a stirrer, and a means of adding sampleand reagents and removing spent reaction mixture. It isdesirable to have a mea
19、ns for cooling the titration vessel to icetemperature.6.2 Instrument Electrodes, platinum with a surface equiva-lent to two No. 26 wires, 4.76-mm long. The wires should be3 to 8 mm apart and so inserted in the vessel that the liquid willcover them.6.3 Instrument Depolarization Indicator, having an i
20、nternalresistance 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 galvanometer or radio tuning eye circuit.46.4 Buret Assembly for Fischer reagent, consisting of a
21、 25or 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 moist air, all vents must be protectedagainst atmospheric moisture by adequate drying tubes con-tainin
22、g anhydrous calcium sulfate.6All stopcocks and jointsshould be lubricated with a lubricant not particularly reactive7with the reagent.6.5 Weighing Bottle, of the Lunge or Grethen type, orequivalent.6.6 Some laboratory equipment suppliers offer a Karl Fis-cher apparatus. The noted model or its equiva
23、lent has beenfound to be suitable.87. 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
24、specifications are available.9Other grades may beused, provided it is first ascertained that the reagent is ofsufficiently high purity to permit its use without lessening theaccuracy of the determination.7.2 Unless otherwise indicated, references to water shall beunderstood to mean reagent water, Ty
25、pe IV, conforming toSpecification D 1193.7.3 Karl Fischer Reagent, equivalent to 5 mg of water/mL.107.4 Methanol (WarningSee 8.1.)Anhydrous, high pu-rity.8. Hazards8.1 MethanolPoison; flammable; may be fatal or causeblindness if swallowed; cannot be made non-poisonous; harm-ful if inhaled.9. Samplin
26、g9.1 A representative sample of the contents of the originalcontainer shall be obtained as directed in Test Method D 1176;even if two phases are present, the water-insoluble phaseshould not be separated.3Flasks made by Rankin Glass Blowing Co., 3920 Franklin Canyon Rd.,Martinez, CA have been found s
27、atisfactory for this purpose.4A type similar to the Precision Scientific Co. “Aquatrator” or Fisher ScientificCo. “Fisher Titrimeter,” is suitable for the measurement of the instrument end point.5A type similar to Catalog No. J-821 of Scientific Glass Apparatus Co.,Bloomfield, NJ, or Catalog No. 750
28、 of Eck and Krebs, New York, NY, has beenspecifically designed for this purpose and presents the minimum contact of reagentwith stopcock lubricant.6Indicating Drierite has been found satisfactory for this purpose.7Suitable lubricants include Apiezon N. (James G. Biddle and Co., Philadelphia,PA); Hig
29、h Vacuum Silicone Grease (Dow Corning Co., Midland, MI); Sisco 300(Swedish Iron and Steel Co., New York, NY).8Metrohm Herisau, Karl Fischer Titrator Type E-452 available from BrinkmannInstruments, Inc., Cantaigue Road, Westbury, NY 11590.9Reagent Chemicals, American Chemical Society Specifications ,
30、 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, U.S. Pharmacopeial Convention, Inc.
31、 (USPC), Rockville,MD.10Reagents, as the pyridine-free hydranal reagent, available from Fisher Scien-tific, Pittsburgh, PA 15219.NOTE 1All dimensions in millimetres.FIG. 1 Titration Flask AssemblyD 1123 99 (2003)e1210. Standardization of Reagent10.1 Standardize the Fischer reagent at least once, pri
32、or touse, each day the procedure is used, by either the color orinstrument end point (see Section 3) method, using the proce-dure as used for titrating the sample (Section 11).10.1.1 Add to each 250 mL flask 25 mL of anhydrous, highpurity methanol. Stir rapidly. Titrate with Karl Fischer reagentacco
33、rding to 11.2. Add to the solution 0.15 to 0.18 g of water(to 60.1 mg) by use of an accurately sized syringe. Titrateagain and record the volume of titrant used. Repeat standard-ization two more times.10.1.2 Calculate the equivalency factor of the reagent interms of water content per millilitre as f
34、ollows:Equivalency factor, F , mg of water/mL 5 A/B (2)where:A = mg of water used in the standardization, andB = Karl Fischer reagent required, mL.11. Procedure11.1 Introduce 30 to 50 mL of the anhydrous high-puritymethanol into a 250 mL Erlenmeyer flask, making sure, if aninstrument end point appar
35、atus is used, that the electrodes arecovered by this amount of methanol. If the color end point is tobe determined, make up a second flask as well.11.2 Adjust the stirrer, if any, to provide adequate mixingwithout splashing. Titrate the mixture to the instrument endpoint (3.1.2), or the color end po
36、int (3.1.1), with Karl Fischerreagent. If the color end point is to be observed, titrate one flaskto match the first. Set aside the first flask as a comparisonstandard for titrating the sample.11.3 To the titration mixture thus prepared, add an amountof sample as indicated in Table 1. Exercise care
37、when thesample is transferred so that water is not absorbed from the air,particularly under conditions of high humidity. Again, titratethe mixture with Karl Fischer reagent to the same instrument orcolor end point previously employed. Record the amount ofreagent used to titrate the water in the samp
38、le.NOTE 2When using the volumetric flask-type titration vessel inhumid climate, place a piece of thin paraffin wax over the mouth of thevessel. Provide a small hole for introducing the buret tip. In less humidclimates it is sufficient to lower the tip of the buret deeply into the longneck of the tit
39、ration flask.NOTE 3In 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 interrupted, touch the burettip to the neck of the flask to remove droplets which, if not remo
40、ved,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.12. Calculation12.1 Calculate the total water content (free plus apparent) ofthe sample as follows:Water, weight % 5 VF/10M (3)where:V = mL of Kar
41、l Fischer reagent required by the sample,F = equivalency factor for Karl Fischer reagent, mg ofwater per mL of reagent, andM = sample used, g.13. Precision and Bias13.1 PrecisionThe following data should be used forjudging the acceptability of results (95 % probability):13.1.1 RepeatabilityDuplicate
42、 results by the same opera-tor should be considered suspect if they differ by more than thefollowing amount:Repeatability 0.5 mL of titrant13.1.2 ReproducibilityThe result submitted by one labo-ratory should not be considered suspect unless it differs fromthat of another laboratory by more than the
43、following amount:Water Content, % Reproducibility, % of mean0.1to1.0 151.0to10 513.2 BiasSince there is no accepted reference materialsuitable for determining the bias for the procedure in this testmethod, bias has not been determined.TEST METHOD BCOULOMETRIC TITRATION14. Apparatus14.1 Coulometric T
44、itrator11,12A complete control unitwith titration chamber and clamp, platinum sensing electrodes,generator, magnetic stirrer, and meeting requirements 14.2 and18.1.14.2 The instrument used for determining water in liquids isdesigned and calibrated to deliver a known number of milli-amperes of curren
45、t which generates sufficient iodine to neu-tralize a known number of micrograms of water per minute.14.3 In order to determine the water content of enginecoolants, this method requires a two-part titration solution thatis brought to zero dryness by iodine produced by the generatorwhen the instrument
46、 is powered up. The sample is added andthe water content is read directly in micrograms.14.4 Glass Syringe, 50-mL, for removing excess solutionfrom the titration chamber.14.5 Syringe, 25-L, fitted with a 11.5-cm hypodermicneedle for introduction of samples into the titration chamber.11This procedure
47、 is patented by the Photovolt Corp. under U. S. Patent3,726,778 and has been included in the standard under Paragraph 11.2 of theRegulations Governing ASTM Technical Committees. Procedure A is a non-patented alternative method.12A detailed drawing is available from ASTM Headquarters. Request Adjunct
48、No. 12-415330-00.TABLE 1 Recommended Sample SizesWater Content,weight %SampleSize,gSample Method2.5 to 10 0.3 Introduce samples by using weigh bottles ordisposable, accurate syringes. Obtain sampleweight by difference.0.5to2.5 3Below 0.5 20D 1123 99 (2003)e1314.6 Syringe, 1-L, fitted with a 11.5-cm
49、hypodermic needlefor standardization of instrument.14.7 Fluorocarbon Sealing Grease,13to seal the titrationchamber against atmospheric moisture.14.8 Septums, to seal sample port but allow introduction ofsamples by a needle with a minimum of moisture contamina-tion. Septum caps should be replaced as required to prevent airleakage as indicated by instrument drift.15. Reagents1415.1 Generator Solution(Warningsee 16.1)Providesiodine in the reaction mixture.15.2 Titration Solutions, supplied in two parts, Part A andPart B. The two parts are mixed prior to a
