Determination of dispersants in gasoline and diesel oil

Abstract

This research is intended to use in the quantitative determination of dispersant additive in gasoline and diesel oil by HPLC/GPC method. This method is used to determine the high molecular weight as polymer which in dispersant package but did not in base oil. The method is directed measurement and is independent of base oil or other small additive. Therefore the method is very accurate, fast and reproducible. The repeatability is more than 95%. The optimum conditions in HPLC/GPC method were PLgel 5 µm 50 A 300x7.5 mm, 100 ℃. Of the EMD temperature, 8 l/min of Nitrogen gas flow rate and 1 ml/min of THF as mobile phase flow rate. In diesel case it must be separated dispersant molecules away from base diesel with conditions such as 2 g. Alumina neutral as absorbent, 10 ml Hexane, 10 ml THF and 25 ml diesel sample. The concentration of dispersant additive in unknown sample was determined by compared the peak area of the first peak in unknown sample with standard calibration curve known sample.