NITROGEN TRIFLUORIDE - A NEW REACTANT GAS IN CHEMICAL-REACTION INTERFACE MASS-SPECTROMETRY FOR DETECTION OF PHOSPHORUS, DEUTERIUM, CHLORINE, AND SULFUR

A new set of reactions that involve fluorine have been investigated in chemical reaction interface mass spectrometry (CRIMS). The primary go al of this study was to provide a means to selectively detect phosphor us-containing compounds, which fluorine does by generating PF5. PF4+, the main fragment ion of PF5, provides a sensitive (10 pg/s), selectiv e, and linear (> 10(3) dynamic range) channel for phosphorus-containin g analytes. This fluorine-rich environment also provides new ways to s electively and simultaneously detect hydrogen isotopes, chlorine, and sulfur. NF3 as a reactant gas provides the most comprehensive array of elemental and isotopic detection yet available for CRIMS. An applicat ion of phosphorus-selective detection was attempted by examination of a plasma sample from a patient who had been treated with cyclophospham ide. The phosphorus-selective channel showed six peaks: one is derivat ized phosphate, two are t-butyldimethylsilyl (TBDMS) derivatives of cy clophosphamide, another two are TBDMS derivatives of 4-hydroxy-eyeloph osphamide, and one is from underivatized cyclophosphamide. The simulta neous detection of chlorine-containing compounds confirmed our results for those peaks related to cyclophosphamide and its metabolite.