Ultrahigh-resolution Fourier transform ion cyclotron resonance mass spectrometry has recently revealed that petroleum crude oil contains heteroatom-containing (N,O,S) organic components having more than 20,000 distinct elemental compositions (C(c)H(h)N(n)O(o)S(s)). It is therefore now possible to contemplate the ultimate characterization of all of the chemical constituents of petroleum, along with their interactions and reactivity, a concept we denote as "petroleomics". Such knowledge has already proved capable of distinguishing petroleum and its distillates according to their geochemical origin and maturity, distillation cut, extraction method, catalytic processing, etc. The key features that have opened up this new field have been (a) ultrahigh-resolution FT-ICR mass analysis, specifically, the capability to resolve species differing in elemental composition by C(3) vs SH(4) (i.e., 0.0034 Da); (b) higher magnetic field to cover the whole mass range at once; (c) dynamic range extension by external mass filtering; and (d) plots of Kendrick mass defect vs nominal Kendrick mass as a means for sorting different compound "classes" (i.e., numbers of N, O, and S atoms), "types" (rings plus double bonds), and alkylation ((-CH(2))(n)) distributions, thereby extending to >900 Da the upper limit for unique assignment of elemental composition based on accurate mass measurement. The same methods are also being applied successfully to analysis of humic and fulvic acids, coals, and other complex natural mixtures, often without prior or on-line chromatographic separation.

Each different molecular elemental composition-e.g., CcHhNnOoSshas a different exact mass. With sufficiently high mass resolving power (m/⌬m 50% Ϸ 400,000, in which m is molecular mass and ⌬m50% is the mass spectral peak width at half-maximum peak height) and mass accuracy (<300 ppb) up to Ϸ800 Da, now routinely available from high-field (>9.4 T) Fourier transform ion cyclotron resonance mass spectrometry, it is possible to resolve and identify uniquely and simultaneously each of the thousands of elemental compositions from the most complex natural organic mixtures, including petroleum crude oil. It is thus possible to separate and sort petroleum components according to their heteroatom class (N nOoSs), double bond equivalents (DBE ‫؍‬ number of rings plus double bonds involving carbon, because each ring or double bond results in a loss of two hydrogen atoms), and carbon number. ''Petroleomics'' is the characterization of petroleum at the molecular level. From sufficiently complete characterization of the organic composition of petroleum and its products, it should be possible to correlate (and ultimately predict) their properties and behavior. Examples include molecular mass distribution, distillation profile, characterization of specific fractions without prior extraction or wet chemical separation from the original bulk material, biodegradation, maturity, water solubility (and oil:water emulsion behavior), deposits in oil wells and refineries, efficiency and specificity of catalytic hydroprocessing, ''heavy ends'' (asphaltenes) analysis, corrosion, etc.Fourier transform ͉ ion cyclotron resonance ͉ mass spectrometry ͉ petroleum ͉ fossil fuel

Although crude acids are minor constituents in petroleum, they have significant implications for crude oil geochemistry, corrosion, and commerce. We have previously demonstrated that a single positive-ion electrospray ionization (ESI) high-field Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) experiment can resolve and identify 3000 chemically different elemental compositions of bases (basic nitrogen compounds) in a crude oil. Here, we show that negative-ion ESI high-field FT-ICR MS can selectively ionize and identify naphthenic acids without interference from the hydrocarbon background. When combined with prechromatographic separation, ESI FT-ICR MS reveals an even more detailed acid composition. An average mass resolving power, m/∆m 50% g 80 000 (∆m 50% is mass spectral peak full width at half-maximum peak height) across a wide mass range (200 < m/z < 1000), distinguishes as many as 15 distinct chemical formulas within a 0.26 Da mass window. Collectively, more than 3000 chemically different elemental compositions containing O 2 , O 3 , O 4 , and O 2 S, O 3 S, and O 4 S were determined in a South American heavy crude. Our data indicates that the crude acids consist of a mixture of structures ranging from C 15 -C 55 with cyclic (1-6 rings) and aromatic (1-3 ring) structures. The acid composition appears to be simpler than that of the corresponding hydrocarbon analogues.