Gas Chromatography Multiphoton Ionization Fourier Transform Mass Spectrometry

A capillary gas chromatograph/Fourler transform mass spectrometer (GC/FTMS) has been upgraded so that a pulsed laser operating at 266 nm can be used for multiphoton ionization (MPI). MPI Is demonstrated to be a selective ionization method for a variety of polycycllc aromatic hydrocarbons (PAHs) In both a test mixture and a sample of gasoline, and the selectivity is consistent with previous research. However, ions can now be detected at mass resolving powers of greater than 20000 (fwhm) up to m/z 200 by using the FT mass spectrometer rather than the often-used time-of-flight mass spectrometer. Detection limits for several of the PAHs are reported to be in the low picogram range (I.e., 7 pg for naphthalene) at both high (>20 000) and low (<5000) resolving powers with a linear dynamic range of 2.5 orders of magnitude. Mass measurement accuracy is also evaluated, and the typical errors are found to be approximately 1-10 ppm (5 ppm) at moderate resolving powers with low ion densities.