1、Designation: D6129 97 (Reapproved 2015)Standard Test Method forSilicon in Engine Coolant Concentrates by AtomicAbsorption Spectroscopy1This standard is issued under the fixed designation D6129; the number immediately following the designation indicates the year oforiginal adoption or, in the case of
2、 revision, 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.1. Scope1.1 This test method covers the determination of silicon inthe range from 200 to 500 ppm in engine
3、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 suitably
4、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 asstandard. No other units of measurement are included in thisstandard.1.3 This stand
5、ard 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.2. Referenced Documents2.1 AS
6、TM Standards:2D1176 Practice for Sampling and Preparing Aqueous Solu-tions of Engine Coolants or Antirusts for Testing Purposes3. 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
7、absorption spectrometer with anitrous oxide-acetylene 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 t
8、o mean dis-tilled water or water of equal quality.5.3 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 exp
9、o-sure to the atmosphere. DO NOT STORE IN GLASS.5.6 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
10、 hydroxide solution to each flask anddilute to volume 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 solu
11、tions areavailable from most laboratory supply companies.6. Sampling6.1 Sample material in accordance with Practice D1176.7. 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.1This test method is under the jurisdiction
12、of ASTM Committee D15 on EngineCoolants and Related Fluids and is the direct responsibility of SubcommitteeD15.04 on Chemical Properties.Current edition approved May 1, 2015. Published June 2015. Originallyapproved in 1997. Last previous edition approved in 2007 as D6129 - 97(2007).DOI: 10.1520/D612
13、9-97R15.2For 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.3Reagent Chemicals, American Chemical Society Specifi
14、cations, 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 Formulatory, U.S. Pharmacopeial Conven
15、tion, Inc. (USPC) Rockville,MD.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States17.2 Using the nitrous oxide-acetylene flame, optimize theinstrument operating conditions for silicon determination at the251.6 nm spectral line according t
16、o the manufacturers recom-mendations.7.3 Obtain the approximate absorbance reading of 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
17、Set the instrument to zero absorbance with the zerostandard solution.7.6 Determine and 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
18、.8. When runningmultiple samples, up to five samples may be run betweenrecalibrations.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 capabilit
19、y of internallycalibrating and directly displaying the concentration contained in thesample 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 3500000sample wt g! 310000(1)where:M = s
20、ilicon in the sample solution, mg/L.8.2 The silicon content may be expressed as specific com-pounds by use of the following conversion calculations:ppm Na2SiO35 ppm Si 34.344 (2)ppm Na2SiO35H2O 5 ppm Si 37.553ppm SiO25 ppm Si 32.1389. Precision and Bias9.1 PrecisionThe repeatability standard deviati
21、on, for asample containing 230 ppm Si, has been determined to be 3ppm. The 95 % 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 pr
22、esented on the bias ofthe procedure in this test method as no material having anaccepted reference value is available.10. Keywords10.1 atomic absorption; engine coolants; silicon; spectros-copyASTM International takes no position respecting the validity of any patent rights asserted in connection wi
23、th any item mentionedin this standard. Users of this standard are expressly advised 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 tech
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25、ion at a meeting of theresponsible technical committee, which you may attend. If you 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 Ha
26、rbor 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). Permission rights to photocopy the standard may also be secured from the Copyright Clearance Center, 222Rosewood Drive, Danvers, MA 01923, Tel: (978) 646-2600; http:/ 97 (2015)2
