1、Designation:D612997(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 revi
2、sion,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 coolant con
3、centratesby 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 adjusting the
4、sample 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 standard does not pu
5、rport 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 ASTM Standards:2D1176
6、 Practice for Sampling and Preparing Aqueous Solu-tions of Engine Coolants orAntirusts 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 absorption spectromete
7、r 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 to mean dis-tilled water or
8、 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 expo-sure to the atmosphere.DO NOT ST
9、ORE 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 hydroxide solution to each flask anddilute
10、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.NOTE1Standard silicon solutions and sodium hydroxide solutions areavailable from most laboratory supply c
11、ompanies.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 of ASTM Committee D15 on EngineCoolants and Related
12、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/D6129-97R15.2For referenced ASTM standards,visit the ASTM websi
13、te,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 Specifications,AmericanChemical Society,Washington,DC.For suggestions on
14、 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 Convention,Inc.(USPC)Rockville,MD.Copyright ASTM International,100 Barr Harbor Driv
15、e,PO Box C700,West Conshohocken,PA 19428-2959.United States1 7.2 Using the nitrous oxide-acetylene flame,optimize theinstrument operating conditions for silicon determination at the251.6 nm spectral line according to the manufacturers recom-mendations.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 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,
