Determination of carboxylic acids in the picomole range after derivatization with pentafluorobenzyl bromide and electron capture gas chromatography

Abstract

A method is presented for the determination of picomole quantities of carboxylic acids by gas chromatography in combination with electron capture detection. The acids are extracted from aqueous media into dichloromethane by ion-pair extraction with tetrapentylammonium ions, and derivatized as their pentafluorobenzyl esters. These derivatives have good chomatographic properties with minimum detectable amounts of ca. 0.15 pg 250 pg or greater quantities of the acids can be used. Recoveries are ca. 90% with a precision of ca. 6% at the 10-ng level.