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 goal of this study was to provide a means to selectively detect phosphorus-containing compounds, which fluorine does by generating PF5. PF4+, the main fragment ion of PF5, provides a sensitive (10 pg/s), selective, and linear (> 105 dynamic range) channel for phosphorus-containing analytes. This fluorine-rich environment also provides new ways to selectively 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 application of phosphorus-selective detection was attempted by examination of a plasma sample from a patient who had been treated with cyclophosphamide. The phosphorus-selective channel showed six peaks: one is derivatized phosphate, two are t-butyldimethylsilyl (TBDMS) derivatives of cyclophosphamide, another two are TBDMS derivatives of 4-hydroxy-yclophosphamide, and one is from underivatized cyclophosphamide. The simultaneous detection of chlorinecontaining compounds confirmed our results for those peaks related to cyclophosphamide and its metabolite