Simultaneous Detection of Anionic Toxic Substances Using GC-MS Analysis of Pentafluorobenzyl Derivatives

Abstract

  A method for the simultaneous detection of anionic toxic substances and related compounds (azide, cyanide, thiocyanate, sulfide, ethyl methylphosphonate, isopropyl methylphosphonate, pinacoryl methylphosphonate (PMPA), methylphosphonate (MPA), nitrate, nitrite) has been developed using gas chromatography-mass spectrometry after pentafluorobenzyl (PFB) derivatization. The PFB derivatives of the analyte anions separated on a HP-5 capillary column were identified by the characteristic electron impact ionization mass spectra (EI-MS). Cyanide gave three kinds of derivatives, and two PMPA diastereomers were separated. The PFB derivative of nitrite could be clearly identified because of the poor resolution from that of nitrate and the absence of distinctive fragmentation ions on EI-MS. The effect of reaction conditions on the yield of the PFB derivatives was investigated. As catalysts, tetradecyldimethylbenzylammonium chloride (TDMBA) and polymer bound tributylmethylphosphonium chloride (TC) were examined. The effect of phosphate (pH 7.0) and borate (pH 9.3) buffer were examined. The pentafluorobenzylation with TC in borate buffer gave the best degree of efficiency except for thiocyanate. The highest yields of PFB derivatives in beverages and blood samples were also given using TC and borate buffer just the same as when tested in water. The derivatization values were 75-100% in the tea sample and 12-100% in the canned coffee sample. For the blood sample, five fold dilution was proved to be necessary in order to avoid coagulation. The derivatization efficiency values were 6-93% in the blood sample. The derivatization yield of MPA was considerably low in the coffee and blood samples.