PENTAFLUOROBENZYL CHLOROFORMATE DERIVATIZATION FOR ENHANCEMENT OF DETECTION OF AMINO-ACIDS OR ALCOHOLS BY ELECTRON-CAPTURE NEGATIVE-ION CHEMICAL-IONIZATION MASS-SPECTROMETRY

Pentafluorobenzyl chloroformate (PFB-chloroformate) has been utilized as a derivatization reagent to impart electron affinity and provide st ructurally relevant fragmentation in electron capture negative ion che mical ionization mass spectrometry (ECNICI-MS). Phenylalanine (Phe) an d decanol were used as model analytes. The conditions used for their d erivatization and the chromatographic and mass spectrometric propertie s of the derivatives are reported. Phenylalanine in aqueous solution w as derivatized in one step by using PFB-chloroformate and a mixture of water, ethanol, and pyridine. The phenylalanine N-pentafluorobenzyl-o xycarbonyl ethyl ester (N-PFBC-Phe-OEt) exhibited good gas chromatogra phic properties and in ECNICI-MS, a dominant [M - 181](-) fragment car ries most of the ion current. Selected ion monitoring experiments on N -PFBC-Phe-OEt resulted in the facile detection of 400 fmol of material . Decanol was derivatized by using anhydrous conditions, and the resul tant pentafluorobenzyl carbonate also exhibited a predominant [M - 181 ](-) ion in ECNICI-MS. Initial results indicate that the ECNICI-MS mol ar response of the decyl pentafluorobenzyl carbonate derivative is six -fold that of the decyl pentafluorobenzoate.