Biodegradation at the Seafloor: Ultrahigh Resolution FT-ICR Mass Spectral Characterization of Natural Petroleum Seeps

Abstract

ABSTRACT We report the first resolution, identification, and characterization of nickel and vanadyl porphyrins simultaneously in weathered oil samples derived from natural seeps in Southern California. Atmospheric pressure photoionization (APPI) Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) provides ultrahigh resolving power (m/Δm50% > 1,000,000 at m/z 500) and sub-ppm mass error (<50 ppb) required to identify nickel porphyrin isotopes for unambiguous elemental composition assignment. We also report the first simultaneous identification and categorization of both vanadyl and nickel porphyrins in the same sample, without prior sample fractionation. More than 85,000 mass spectral peaks are resolved and identified in a single mass spectrum, and represent the most extensive molecular deconvolution of an organic mixture characterized to date.