ASTM D4053 Test Method for Benzene in Motor and Aviation Gasoline by Infrared Spectroscopy
11. Procedure
11.1 Clean the cell with isooctane or similar solvent and dry by means of a source of vacuum.
11.2 Fill the absorption cell with the gasoline to be tested. Both cell and sample should be at ambient temperature during this operation. If moisture condensation is a problem, blanket the cell with a dry, inert atmosphere. Use care to avoid formation of air pockets in the cell and scan immediately to prevent bubbles from forming. Observe the cell during the scan period to check for bubble formation.
11.3 Scan the infrared spectrum from 690 cm(-1) (14.99 µm) to 440 cm(-1) (22.73 µm) versus a clear reference block in the reference beam (for double-beam operation); follow the directions of the manufacturer for quantitative analysis.
11.4 Determine the corrected net absorbance of the benzene band as described in 10.3.3.
11.5 Divide the benzene band corrected net absorbance, as found in 11.4, by the cell path length in millimetres.
12. Calculation
12.1 Calculate the benzene content of the gasoline in liquid volume % by entering the calibration curve of 10.3.6 or the equation in Note 2 with the value of the benzene band found in 11.5.
12.2 If the results are desired on a weight basis, convert to mass %, as follows:
B = V x 0.8844/R
where:
B = benzene, mass %
V = benzene, volume % and
R = relative density of sample, 15/15°C.
