A new spectral deconvolution - selected ion monitoring method for the analysis of alkylated polycyclic aromatic hydrocarbons in complex mixtures.

A new gas chromatography/mass spectrometry (GC/MS) method is proffered for the analysis of polycyclic aromatic hydrocarbons (PAH) and their alkylated homologs in complex samples. Recent work elucidated the fragmentation pathways of alkylated PAH, concluding that multiple fragmentation patterns per homolog (MFPPH) are needed to correctly identify all isomers. Programming the MS in selected ion monitoring (SIM) mode to detect homolog-specific MFPPH ions delivers the selectivity and sensitivity that the conventional SIM and/or full scan mass spectrometry methods fail to provide. New spectral deconvolution software eliminates the practice of assigning alkylated homolog peaks via pattern recognition within laboratory-defined retention windows. Findings show that differences in concentration by SIM/molecular ion detection of C1-C4 PAH, now the standard, yield concentration differences compared to SIM/MFPPH of thousands of percent for some homologs. The SIM/MFPPH methodology is also amenable to the analysis of polycyclic aromatic sulfur heterocycles (PASH) and their alkylated homologs, since many PASH have the same m/z ions as those of PAH and, thus, are false positives in SIM/1-ion PAH detection methods.