QUALITY-CONTROL OF RAPESEED OIL METHYL-ESTERS BY DETERMINATION OF ACYL CONVERSION

A simple procedure for the evaluation of vegetable oil conversion to m ethyl esters of fatty acids has been developed. These methyl esters, p repared by the transesterification of vegetable oil with methanol, are used as alternative fuel for diesel engines. A method of gas-liquid c hromatography (GLC) on packed columns is used to determine the convers ion of acyls bound in acylglycerols to methyl esters. This procedure i s based on comparison of the peak areas of methyl esters in fuel sampl es before and after reaction with an effective transesterification rea gent, which will trans form unreacted acylglycerols to methyl eaters. A correlation between the bound glycerol content, determined by the th in layer chromatography/flame-ionization detector method, and the acyl conversion, determined by GLC, is given. In acyl conversions to methy l esters over 96.0%, the bound glycerol content is less than 0.25% by weight.