Petroleomics: a test bed for ultra-high-resolution Fourier transform ion cyclotron resonance mass spectrometry.

Within a relative abundance dynamic range of approximately 10,000:1, the world's most compositionally complex organic mixture is petroleum crude oil. As such, it provides the most challenging target for mass spectral resolution and identification of molecules below m/z 2000. The mass "splits" in petroleum include most of those that also appear in proteomics, metabolomics and other complex organic mixture analysis. Therefore, petroleum provides an excellent test bed for optimizing mass spectrometer performance in general. The presence of multiple elemental compositions spanning less than 1 Da in mass facilitates mapping and correction of rf phase variation across a Fourier transform ion cyclotron resonance mass spectrum, as well as exposing otherwise inaccessible systematic mass deviations, for additional improvement in mass resolving power and mass accuracy by a factor of up to 5. Internal mass calibration, combined with systematic peak assignment for successive homologous series, enables automated elemental composition assignment of tens of thousands of peaks in a single mass spectrum.