ASTM D3237 Test Method for Lead In Gasoline By Atomic Absorption Spectroscopy
5. Apparatus
5.1 Atomic Absorption Spectrometer, capable of scale expansion and nebulizer adjustment, and equipped with a slot burner and premix chamber for use with an air-acetylene flame.
5.2 Volumetric Flasks, 50-mL, 100-mL, 250-mL, and 1-L sizes.
5.3 Pipets, 2-mL, 5-mL, 10-mL, 20-mL, and 50-mL sizes.
5.4 Micropipet, 100-µL, Eppendorf type or equivalent.
6. Reagents
6.1 Purity of Reagents - Reagent grade chemicals shall be used in all tests. Unless otherwise indicated, it is intended that all reagents shall conform to the specifications of the Committee on Analytical Reagents of the American Chemical Society, where such specifications are available.
6.2 Purity of Water - Unless otherwise indicated, references to water shall be understood to mean reagent water as defined by Types II or III of Specification D1193.
6.3 Aliquat 336 (tricapryl methyl ammonium chloride).
6.4 Aliquat 336/MIBK Solution (10 % volume per volume) - Dissolve and dilute 100 mL (88.0 g) of Aliquat 336 with MIBK to 1 L.
6.5 Aliquat 336/MIBK Solution (1 % volume per volume) - Dissolve and dilute 10 mL (8.8 g) of Aliquat 336 with MIBK to 1 L.
6.6 Iodine Solution - Dissolve and dilute 3.0 g of iodine crystals with toluene to 100 mL.
NOTE 1 - Warning: Flammable. Vapor harmful.
6.7 Lead Chloride (PbCl2).
6.8 Lead-Sterile Gasoline - Gasoline containing less than 0.005 g Pb/gal (1.32 mg Pb/L).
NOTE 2 - Warning: Extremely flammable. Harmful if inhaled. Vapors may cause flash fire.
NOTE 3 - To confirm lead concentrations of less than 0.005 g Pb/gal (1.32 mg Pb/L) refer to Test Methods D1368 and D3116. A procedure for the purification of gas turbine fuel appears in Appendix A 4 of Test Method D2550 and can be used to decrease the lead concentration of low lead gasoline in lead-sterile gasoline.
6.9 Lead, Standard Solution (5.0 g Pb/gal (1.32 g Pb/L)) - Dissolve 0.4433 g of lead chloride (PbCl2) previously dried at 105°C for 3 h in about 200 mL of 10 % Aliquat 336/MIBK solution in a 250-mL volumetric flask. Dilute to the mark with the 10 % Aliquat solution, mix, and store in a brown bottle having a polyethylene-lined cap. This solution contains 1321 µg Pb/mL, which is equivalent to 5.0 g Pb/gal.
6.10 Lead, Standard Solution (1.0 g Pb/gal (264 mg Pb/L)) - By means of a pipet, accurately transfer 50.0 mL of the 5.0 g Pb/gal (1.32 g Pb/L) solution to a 250-mL volumetric flask, dilute to volume with 1 % Aliquat/MIBK solution. Store in a brown bottle having a polyethylene-lined cap.
6.11 Lead, Standard Solutions (0.02, 0.05, and 0.10 g Pb/gal (5.3, 13.2, and 26.4 mg Pb/L)) - Transfer accurately by means of pipets 2.0, 5.0, and 10.0 mL of the 1.0-g Pb/gal (264 mg Pb/L) solution to 100-mL volumetric flasks; add 5.0 mL of 1 % Aliquat 336 solution to each flask; dilute to the mark with MIBK. Mix well and store in bottles having polyethylene-lined caps.
6.12 Methyl Isobutyl Ketone (MIBK), (4-methyl-2-pentanone).
7. Sampling
7.1 Take samples of gasoline in compliance with the instructions in Practice D4057.
7.2 Collect sample in a metal container that can be sealed against leakage and store under temperature-consistent conditions prior to analysis.
