Gas chromatographic determination and gas chromatographic-mass spectrometric determination of dialkyl phosphates via extractive pentafluorobenzylation using a polymeric phase-transfer catalyst

Abstract

A GC and GC-MS procedure was established for dialkyl phosphates (DAP), including dialkyl thiophosphates and dialkyl dithiophosphates (alkyl = Me, Et) via extractive pentafluorobenzylation using a polymeric phase-transfer catalyst (tri-phase catalyst). The abilities of five tri-phase catalysts were compared and among them tri- n-butylmethylphosphonium bromide, polymer bound [0.75 mequiv. Br −/g, 200–400 mesh (TB-0.75)], was found to be the most effective. The dialkyl thiosphosates and dialkyl dithiophosphates in an aqueous sample were readily extracted in the form of their pentafluorobenzyl (PFB) derivatives when the reaction mixture consisting of buffered aqueous sample, toluene, pentafluorobenzyl bromide and TB-0.75 was stirred at 45°C. The extractive pentafluorobenzylation of dimethyl phosphate and diethyl phosphate was effetted with an additional reaction at 90°C. It was also found that DAP, even in a relatively large volume of aqueous sample, could be captured efficiently by this catalyst.