GAS-CHROMATOGRAPHIC DETERMINATION AND GAS-CHROMATOGRAPHIC MASS-SPECTROMETRIC DETERMINATION OF DIALKYL PHOSPHATES VIA EXTRACTIVE PENTAFLUOROBENZYLATION USING A POLYMERIC PHASE-TRANSFER CATALYST

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-phas e catalysts were compared and among them tri-n-butylmethylphosphonium bromide, polymer bound [0.75 mequiv. Br-/g, 200-400 mesh (TB-0.75)], w as found to be the most effective. The dialkyl thiosphosates and dialk yl dithiophosphates in an aqueous sample were readily extracted in the form of their pentafluorobenzyl (PFB) derivatives when the reaction m ixture consisting of buffered aqueous sample, toluene, pentafluorobenz yl bromide and TB-0.75 was stirred at 45 degrees C. The extractive pen tafluorobenzylation of dimethyl phosphate and diethyl phosphate was ef fected with an additional reaction at 90 degrees C. It was also found that DAP, even in a relatively large volume of aqueous sample, could b e captured efficiently by this catalyst.