ASTM D6129-97(R2021) pdf free download

ASTM D6129-97(R2021) pdf free download.Standard Test Method for Silicon in Engine Coolant Concentrates by Atomic Absorption Spectroscopy
1. Scope
1.1 This test method covers the determination of silicon in the range from 200 ppm to 500 ppm in engine coolant concentrates by atomic absorption. This method is as accurate and precise as photometric methods, while requiring consider- ably less operator time and avoiding problems with reagent instability. 1.1.1 Coolants with silicon content outside of this range may be analyzed by this method by suitably adjusting the sample size. Care should be taken to ensure that the glycol content of the working standards corresponds to that of the sample solution being analyzed. 1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard. 1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appro- priate safety, health, and environmental practices and deter- mine the applicability ofregulatory limitations prior to use. 1.4 This international standard was developed in accor- dance with internationally recognized principles on standard- ization established in the Decision on Principles for the Development of International Standards, Guides and Recom- mendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
2. Referenced Documents
2.1 ASTM Standards: 2 D1176 Practice for Sampling and Preparing Aqueous Solu- tions of Engine Coolants orAntirusts for Testing Purposes
3. Summary of Test Method
3.1 The sample is dissolved in water and the silicon content is determined from a standard curve established at the time the sample is run. An atomic absorption spectrometer with a nitrous oxide-acetylene flame is used.
4. Apparatus
4.1 Atomic Absorption Spectrometer, with nitrous oxide- acetylene flame. 4.2 Hollow-Cathode Lamp, for silicon.
5. Reagents
5.1 Reagent grade chemicals shall be used in all tests. 3 5.2 References to water shall be understood to 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 when analyzing PG-based coolants). 5.5 Sodium Hydroxide, 5 % in water (see Note 1). When preparing from solid sodium hydroxide avoid prolonged expo- sure to the atmosphere. DO NOT STORE IN GLASS. 5.6 Working standards: 0 mg ⁄L, 20 mg ⁄L, 40 mg ⁄L, and 60 mg ⁄L silicon. 5.6.1 Prepare these solutions by pipeting 2.0 mL, 4.0 mL, and 6.0 mL of the 1000 mg/L standard silicon solution into separate 100 mL volumetric flasks. Add 10.0 mL of ethylene glycol and 2.0 mL of 5 % sodium hydroxide solution to each flask and dilute to volume with water. Prepare the zero standard solution by adding 10.0 mL ethylene glycol and 2.0 mL 5 % sodium hydroxide solution to another 100 mL volumetric flask and diluting to volume with water. N OTE 1—Standard silicon solutions and sodium hydroxide solutions are available from most laboratory supply companies.
7. Procedure
7.1 To the nearest 0.001 g, weigh 5 g ofsample into a 50 mL volumetric flask. Dissolve in and dilute to volume with water. 7.2 Using the nitrous oxide-acetylene flame, optimize the instrument operating conditions for silicon determination at the 251.6 nm spectral line according to the manufacturer’s recom- mendations. 7.3 Obtain the approximate absorbance reading of the sample solution versus the zero standard solution (containing glycol and sodium hydroxide). 7.4 Choose the working standard solutions that will give absorbance readings lower and higher than that of the sample. 7.5 Set the instrument to zero absorbance with the zero standard solution. 7.6 Determine and record the absorbance of each working standard solution. 7.7 Determine and record the absorbance of the sample solution. 7.8 Recheck the standards to verify the calibration. If the calibration has changed, repeat 7.5 – 7.8. When running multiple samples, up to five samples may be run between recalibrations. 7.9 Plot a standard curve using absorbance versus mg/L silicon (see Note 2). 7.10 From the standard curve determine the mg/L of silicon contained in the sample solution.