Chemical ionization using CF3+: Efficient detection of small alkanes and fluorocarbons

The trifluoromethyl ion CF₃⁺ is evaluated as a chemical ionization (CI) precursor in a compact Fourier Transform Ion Cyclotron Resonance (FTICR) mass spectrometer. It reacts with alkanes by hydride abstraction allowing characterization and quantification of alkanes up to C4 and cyclic. With larger alkanes fragmentation occurs. Fluorocarbons react by fluoride abstraction. Rate coefficients have been measured for reaction with alkanes, fluoroalkanes, chlorofluoroalkanes as well as several common VOCs. Use of CF₃⁺ for trace analysis in air has been tested on an air sample containing traces of acetone, toluene, benzene and cyclohexane. The results are consistent with those obtained with H₃O⁺ precursor and allow additional cyclohexane quantification.