title: Computerised gas chromatographic-mass spectrometric analysis of complex mixtures of alkyl porphyrins.
abstract: Computerised capillary gas chromatography-mass spectrometry (GC-MS) analysis of complex mixtures of alkyl porphyrins, as their bis-(trimethylsiloxy)silicon(IV) and bis(tert.-butyldimethylsiloxy)silicon(IV) derivatives, is described.  The latter derivative is more suitable for routine GC-MS analysis.  This computerised GC-MS approach, when applied to the alkyl porphyrins of two geological samples, a bitumen (Gilsonite, Eocene age, UT, U.S.A.) and a crude oil (Boscan, Cretaceous age, West Venezuela), has revealed the highly complex compositions of these fractions.  Computer-aided data processing, using relative retention index (RRI) calculations, facilitated the classification of the chromatographic peaks according to structural type and membership of pseudo-homologous series.  Computerised GC-MS is compared with, and contrasted to high-performance liquid chromatography as a means of petroporphyrin analysis.
authors.affiliation: Organic Geochemistry Unit, University of Bristol, U.K.
authors.forename: P J
authors.initials: PJ
authors.lastname: Marriott
authors.forename: J P
authors.initials: JP
authors.lastname: Gill
authors.forename: R P
authors.initials: RP
authors.lastname: Evershed
authors.forename: C S
authors.initials: CS
authors.lastname: Hein
authors.forename: G
authors.initials: G
authors.lastname: Eglinton
mesh_terms: D002623:Chemistry Techniques, Analytical / Q000379:methods; D002851:Chromatography, High Pressure Liquid; D001330:Electronic Data Processing; D008401:Gas Chromatography-Mass Spectrometry / Q000295:instrumentation / Q000379:methods*; D019015:Geologic Sediments / Q000032:analysis*; D005844:Geology / Q000379:methods; D006838:Hydrocarbons / Q000032:analysis; D017646:Organosilicon Compounds / Q000032:analysis*; D010578:Petroleum / Q000032:analysis; D011166:Porphyrins / Q000032:analysis* / Q000302:isolation & purification; D012984:Software
chemical_list: D006838:Hydrocarbons; D017646:Organosilicon Compounds; D010578:Petroleum; D011166:Porphyrins; C006647:asphalt