EXTRACTIVE PENTAFLUOROBENZYLATION USING A POLYMERIC PHASE-TRANSFER CATALYST - A CONVENIENT ONE-STEP PRETREATMENT FOR GAS-CHROMATOGRAPHIC ANALYSIS OF ANIONIC COMPOUNDS

An extractive pentafluorobenzylation procedure has been established fo r gas chromatographic analysis of various anionic compounds using a po lymer-bound phase-transfer catalyst and pentafluorobenzyl bromide as t he derivatization reagent. The efficiency of five polymer-bound cataly sts was compared, and tri-n-butylmethylphosphonium bromide, polymer bo und (0.75 mequ Br-/g, 200-400 mesh) was found to be the most effective . Varieties of carboxylates and phenolates in aqueous samples were rea dily extracted as pentafluorobenzyl (PFB) derivatives with the excepti on of certain compounds, such as picrate which is a weak base and ster ically-hindered. The conditions for extractive derivatization for both individual and simultaneous analyses were optimized. Simultaneous der ivatization could be performed under moderate conditions (i.e. at pH 6 .5, 60 degrees C). Traces of such anionic compounds, even in a relativ ely large volume of aqueous sample, could be efficiently captured and converted by the catalyst, and then concentrated in a small-volume org anic layer as PFB derivatives. (C) 1997 Elsevier Science B.V.