Total alkylated polycyclic aromatic hydrocarbon characterization and quantitative comparison of selected ion monitoring versus full scan gas chromatography/mass spectrometry based on spectral deconvolution.

Quantitative information of alkylated PAH is frequently used in forensic investigations to characterize petroleum releases and fate in the environment. Interference from a complex matrix often obviates target compound quantitation. Using single ion SIM or a single mass spectral pattern to analyze these homologs should result in either over- or underestimating their concentration. To confirm this hypothesis, a library of C(1)-C(4) alkylated PAH fragmentation patterns were made from automated sequential two-dimensional GC-GC/MS data and the Ion Signature deconvolution software. Based on these patterns, 1D GC/MS data was compared using single ion extraction and one fragmentation pattern per homolog against data obtained from those peaks whose scans met the spectral deconvolution criteria. Significant overestimation occurs when a single ion is used to extract peak signal for C(4)-naphthalene, C(1)-fluorene, and the C(1)- to C(3)-dibenzothiophenes. In contrast, C(2)-naphthalene, C(2)-fluorene, C(3)-phenanthrene, and C(1)-dibenzothiophene were underestimated by >50% when one fragmentation pattern per homolog was used. The Ion Signature deconvolution software makes it easy to interpret mass spectrometry data, especially in complex environmental samples like diesel fuel.