Gas chromatographic procedure for the determination of meta- and para-hydroxyphenylacetic acids

m- and p-Hydroxyphenylacetic acids have been identified and quantitated in rat brain by gas chromatography of their pentafluoropropionyl hexafluoroisopropyl diesters. The procedure differs from those employed in earlier studies on the catecholic acids in that a support-coated open-tubular column was used, a preliminary purification of the acids by thin-layer chromatography was carried out, and excess derivatizing reagent was removed by extraction with a phosphate buffer.