ASTM D4046 Test Method for Alkyl Nitrate in Diesel Fuels by Spectrophotometry
9. Procedure
9.1 Pipet 1.0 mL of test specimen into a 10-mL volumetric flask and dilute to volume with isopropyl alcohol.
9.2 Pipet 1.0 mL of the sample test specimen prepared in 9.1 into a 125-mL separatory funnel. To another funnel add 1.0 mL of blank isopropyl alcohol.
NOTE 4 - A more accurate blank would be obtained if the same base stock as the samples diluted with isopropyl alcohol, were used.
9.3 Follow steps 8.4-8.9.
NOTE 5 - If an absorbance is too high, dilute an aliquot of the solution five-fold with blank solution and correct calculations accordingly.
9.4 Subtract the absorbance of the blank from the absorbance of the samples and calculate the result using the slope of the calibration curve.
Alkyl nitrate, volume % = CD
where:
C = slope of the calibration curve and
D = absorbance of the sample.
