Differentiation of isomeric polyaromatic hydrocarbons by electrospray Ag(I) cationization mass spectrometry

Abundant Ag(I)‐cationized complexes of 13 polyaromatic hydrocarbons (PAHs), [Ag+PAH] + and [Ag+2(PAH)] + , were readily generated by electrospray ionization (ESI). In‐source collision‐induced dissociation (CID) of the [Ag+2(PAH)] + complex yielded the monomer complex [Ag+PAH] + , which fragmented further to yield the radical molecular ion [PAH] +. . Based on significant differences in relative intensities of [Ag+2(PAH)] + , [Ag+PAH] + and [PAH] +. , isomeric PAHs can be differentiated. The [PAH] +. /[Ag+PAH] + ion intensity ratio was found to increase with decreasing ionization potentials (IPs) of PAHs. The ratio was significantly different for the isomeric PAHs studied over a wide range of PAH concentrations (1.6–100 nmol/mL), and showed good measurement reproducibility; the coefficient of variation of inter‐day measurements was in the range 3–12% for four representative PAHs (n = 5). Detection limits for phenanthrene, pyrene, chrysene and benzo[a]pyrene, in the form of the monomer complexes [ 107 Ag+PAH] + and measured in the selected‐ion monitoring (SIM) mode, were 0.31, 0.63, 0.16 and 1.25 pmol/5 μL injection, respectively (S/N ratio ∼2–3). Copyright © 2003 John Wiley & Sons, Ltd.