1、Designation: D 6129 97 (Reapproved 2007)Standard Test Method forSilicon in Engine Coolant Concentrates by AtomicAbsorption Spectroscopy1This standard is issued under the fixed designation D 6129; 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.1. Scope1.1 This test method covers the determination of silicon inthe range from 200 to 500 ppm in engi
3、ne coolant concentratesby atomic absorption. This method is as accurate and precise asphotometric methods, while requiring considerably less opera-tor time and avoiding problems with reagent instability.1.1.1 Coolants with silicon content outside of this rangemay be analyzed by this method by suitab
4、ly adjusting thesample size. Care should be taken to ensure that the glycolcontent of the working standards corresponds to that of thesample solution being analyzed.1.2 The values stated in SI units are to be regarded as thestandard.1.3 This standard does not purport to address all of thesafety conc
5、erns, 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.2. Referenced Documents2.1 ASTM Standards:2D 1176 Practice for Sampling and Prepar
6、ing Aqueous So-lutions of Engine Coolants or Antirusts for Testing Pur-poses3. Summary of Test Method3.1 The sample is dissolved in water and the silicon contentis determined from a standard curve established at the time thesample is run. An atomic absorption spectrometer with anitrous oxide-acetyle
7、ne flame is used.4. Apparatus4.1 Atomic Absorption Spectrometer, with nitrous oxide-acetylene flame.4.2 Hollow-Cathode Lamp, for silicon.5. Reagents5.1 Reagent grade chemicals shall be used in all tests.35.2 References to water shall be understood to mean dis-tilled water or water of equal quality.5
8、.3 Standard Silicon Solution, 1000 mg/L (see Note 1).5.4 Ethylene Glycol (propylene glycol should be used whenanalyzing PG-based coolants).5.5 Sodium Hydroxide, 5 % in water (see Note 1). Whenpreparing from solid sodium hydroxide avoid prolonged expo-sure to the atmosphere. DO NOT STORE IN GLASS.5.6
9、 Working standards: 0, 20, 40, and 60 mg/L silicon.5.6.1 Prepare these solutions by pipeting 2.0, 4.0, and 6.0mL of the 1000 mg/L standard silicon solution into separate100 mL volumetric flasks. Add 10.0 mL of ethylene glycol and2.0 mL of 5 % sodium hydroxide solution to each flask anddilute to volu
10、me with water. Prepare the zero standard solutionby adding 10.0 mL ethylene glycol and 2.0 mL 5 % sodiumhydroxide solution to another 100 mL volumetric flask anddiluting to volume with water.NOTE 1Standard silicon solutions and sodium hydroxide solutions areavailable from most laboratory supply comp
11、anies.6. Sampling6.1 Sample material in accordance with Test MethodD 1176.7. Procedure7.1 To the nearest 0.001 g, weigh 5 g of sample into a 50 mLvolumetric flask. Dissolve in and dilute to volume with water.7.2 Using the nitrous oxide-acetylene flame, optimize theinstrument operating conditions for
12、 silicon determination at the251.6 nm spectral line according to the manufacturers recom-mendations.1This specification is under the jurisdiction ofASTM Committee D15 on EngineCoolants and is the direct responsibility of Subcommittee D15.04 on ChemicalProperties.Current edition approved April 1, 200
13、7. Published April 2007. Originallyapproved in 1997. Last previous edition approved in 2002 as D 6129 - 97(2002).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
14、 standards Document Summary page onthe ASTM website.3Reagent 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., P
15、oole, Dorset, U.K., and the United States Pharmacopeiaand National Formulatory, U.S. Pharmacopeial Convention, Inc. (USPC) Rockville,MD.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.7.3 Obtain the approximate absorbance reading of
16、thesample solution versus the zero standard solution (containingglycol and sodium hydroxide).7.4 Choose the working standard solutions that will giveabsorbance readings lower and higher than that of the sample.7.5 Set the instrument to zero absorbance with the zerostandard solution.7.6 Determine and
17、 record the absorbance of each workingstandard solution.7.7 Determine and record the absorbance of the samplesolution.7.8 Recheck the standards to verify the calibration. If thecalibration has changed, repeat 7.5-7.8. When running multiplesamples, up to five samples may be run between recalibrations
18、.7.9 Plot a standard curve using absorbance versus mg/Lsilicon (see Note 2).7.10 From the standard curve determine the mg/L of siliconcontained in the sample solution.NOTE 2If the instrument in use has the capability of internallycalibrating and directly displaying the concentration contained in the
19、sample solution, manual construction of a calibration curve is, of course,unnecessary.8. Calculation8.1 Calculate the silicon content of the sample as follows:silicon, ppm 5M 3 500 000sample wt g!310 000(1)where:M = silicon in the sample solution, mg/L.8.2 The silicon content may be expressed as spe
20、cific com-pounds by use of the following conversion calculations:ppm Na2SiO35 ppm Si 3 4.344 (2)ppm Na2SiO35H2O 5 ppm Si 3 7.553ppm SiO25 ppm Si 3 2.1389. Precision and Bias9.1 PrecisionThe repeatability standard deviation, for asample containing 230 ppm Si, has been determined to be 3ppm. The 95 %
21、repeatability limit has been determined to be 8ppm. The reproducibility standard deviation has been deter-mined to be 8 ppm. The 95 % reproducibility limit has beendetermined to be 22 ppm.9.2 BiasNo information can be presented on the bias ofthe procedure in this test method as no material having an
22、accepted reference value is available.10. Keywords10.1 atomic absorption; silicon; engine coolants;spectroscopyASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of this standard are expressly advise
23、d that determination of the validity of any such patent rights, and the riskof infringement of such rights, are entirely their own responsibility.This standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years andif not revised, either re
24、approved or withdrawn. Your comments are invited either for revision of this standard or for additional standardsand should be addressed to ASTM International Headquarters. Your comments will receive careful consideration at a meeting of theresponsible technical committee, which you may attend. If y
25、ou feel that your comments have not received a fair hearing you shouldmake your views known to the ASTM Committee on Standards, at the address shown below.This standard is copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,United States. Individual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website(www.astm.org).D 6129 97 (2007)2
