Methyl and ethyl chloroformate derivatizations for compound-specific stable isotope analysis (CSIA) of fatty acids

Abstract

We evaluated methyl (MCF) and ethyl chloroformate (ECF) derivatizations as rapid and simple esterification techniques for the compound-specific stable isotope analysis (CSIA) of fatty acids. Although the fatty acids were esterified very rapidly (within 5min) at room temperature in both derivatizations, the yield of derivatives depended strongly on the chemical constituent and pH of the derivative reagent and the carbon-chain length of fatty acids. In this study, quantitative esterification was observed during ethyl esterification with ECF:ethanol:pyridine (2:60:5, v:v). In this esterification process, the accuracy of the carbon isotope (δ¹³C) measurements was always better than 0.3‰.