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A method is described for the liquid chromatography/tandem mass spectrometry analysis of free base porphyrins, which allows the routine and rapid recognition of alkyl substituents in the components of complex natural mixtures. The method overcomes difficulties associated with probe tandem mass spectrometry or liquid chromatography/mass spectrometry which can arise from the numerous isobaric ions present in the spectra and the associated uncertainty in assigning fragment ions to individual components. MS and MS/MS spectra of synthetic and natural free base porphyrin standards are compared to identify spectral patterns which allow recognition of extended alkyl chains. In natural mixtures, the identification of cycloalkano porphyrins with such chains is based on comparison of product ion spectra of a series of C31–C35 standards and the presence of diagnostic ions which can be attributed to losses associated with >C2 alkyl chains. Liquid chromatography/tandem mass spectrometry analysis of a free base porphyrin mixture from Serpiano oil shale is carried out to obtain MS/MS spectra of palaeoenvironmentally significant minor components. The results reveal the presence of cycloalkano porphyrins with >C2 substituents in the shale, suggesting the occurrence of photic zone anoxia in the original depositional setting. Copyright © 1999 John Wiley & Sons, Ltd.

The (22 R )-30a,30b-dihomohopan-30b-yl and tetrahymanyl esters of pyrophaeophorbide a , chlorophyll a transformation products resulting from zooplankton herbivory, occur in an extract of surface sediment from Lake Valencia (Venezuela). The former was identified by HPLC-PDA-MS comparison with a standard and the latter after reduction of the extract and GC-MS analysis of the released alcohols.

Maleimides (1 H -pyrrole-2,5-diones), degradation products of photosynthetic tetrapyrrole pigments, have been found for the first time in the polar fraction of the solvent extracts of two marine sediments deposited in restricted basins: Kupferschiefer (Permian) and Serpiano shale (Mid-Triassic). GC and GC—MS analyses of the TBDMS ( tertiary -butyldimethylsilyl) derivatives show a simple component distribution, dominated by Me Et maleimide, mainly of planktonic origin; Me n -Pr and Me i -Bu maleimides, present in low abundance, are thought on structural grounds to be derived from the bacteriochlorophylls c, d , or e of Chlorobiaceae (anoxygenic green sulfur bacteria). This is confirmed for Kupferschiefer by isotope ratio monitoring (irm) GCMS which shows them to be enriched in 13 C as a result of their photosynthetic carbon assimilation, which takes place by the reversed tricarboxylic acid (TCA) cycle. The structurally more specific Me i -Bu maleimide is, however, slightly more enriched in 13 C than Me n -Pr maleimide, suggesting that the latter is derived in part from reduction of the C 3 -acid substituent at C-17 of phytoplanktonic chlorophyll. These results provide evidence for the existence in both depositional settings of microbial communities containing Chlorobiaceae. In turn, this indicates that there must have been periods when the water column was highly stratified and anoxia extended into the zone of light penetration.

Kerogens isolated from nine samples from a single marl bed of the Gessoso-solfifera formation in the Vena del Gesso basin (Upper Miocene, Italy) were treated with CrCl 2 and Li/EtNH 2 to remove inorganic and organic sulphur, respectively. The untreated and “desulphurized” (CrCl 2 and Li/EtNH 2 ) kerogens were qualitatively and quantitatively analyzed by flash pyrolysis-gas chromatography-mass spectrometry. Typically, significant variations in the relative contributions and abundances of n -alk-1-enes/ n -alkanes, alkylated pyrroles, thiophenes and supposedly S-bound moieties released as phytenes and sterenes were observed. The first series of products ( n -hydrocarbons) contributed relatively more to the pyrolyzates of the desulphurized kerogens, suggesting an enrichment of microalgal-derived aliphatic macromolecules. These marine micro-organisms are thought to belong in part to the class of Eustigmatophyceae. Alkylated pyrroles were barely detectable in the untreated kerogen pyrolyzates, whereas they contributed significantly to those from the treated kerogens. Similar treatment of a porphyrin, octaethylporphyrin, revealed that alkyl porphyrins are thermally too stable to be cleaved upon pyrolysis. However, Li/EtNH 2 treatment reduced the porphyrin standard, such that it could generate mainly monopyrroles upon pyrolysis. It is concluded that Li/EtNH 2 treatment reduced tetrapyrrole moieties bound to the desulphurized kerogen network.

The iron porphyrin fraction of Kupferschiefer, an organic-rich sedimentary rock deposited in the Zechstein Sea during the Permian (ca. 235Myr before present) contains three minor components characterised by 1 H NMR spectroscopy. The carbon skeletons correlate specifically with members of one series of the bacteriochlorophylls d of the Chlorobiaceae, which are obligate anaerobes. Their structures therefore reveal the occurrence of anoxic conditions extending up into the zone of light penetration in the water column of the original depositional setting in the Lower Rhine Basin.

Lithium in ethylamine ( Li EtNH 2 ) treatment has been carried out on sulphur-rich kerogens from 10 sub-samples of the cycle IV marl from the Vena del Gesso evaporitic sediments (Upper Miocene, Italy). The treatment releases, after chromatography of the resulting solvent extracts, up to 30% of the kerogen total organic carbon. The biomarkers released are dominated by components of algal origin. The concentrations of the aliphatic hydrocarbons obtained are of the same order of magnitude as the bound alkanes released upon desulphurization of polar fractions from organic extracts and show similar distributions. The presence of diaromatic isoprenoids derived from Chlorobiaceae indicates that photic zone anoxia occurred during the deposition of the cycle IV marl, such conditions being more prevalent at the middle of the section. Polar material makes up by far most of the organic material released and contains in particular alcohols and amides which may result from the cleavage of ester bonds present in these immature kerogens, the amides being secondary products formed by reaction with the EtNH2. In the case of the alcohols, however, these components could also arise from cleavage of sulphide-bound moieties.

Liquid chromatography/mass spectrometry with an atmospheric pressure chemical ionization interface permits the routine study of mixtures of algal-derived, chlorophyll transformation products isolated from biological and environmental samples. Interpretation of the mass spectra of standards of chlorophyll a and three of its commonly occurring transformation products has allowed the identification of components found in extracts from zooplankton faecal pellets and a marine surface sediment. This highly sensitive technique should prove valuable for pigment analysis in environmental studies.

A suite of steryl esters of pyrophaeophorbide a ( 1a ), a water column degradation product of phytoplankton chlorophyll a, has been prepared in good yield using dicyclohexylcarbodiimide as dehydrating agent. Comparison and co-injection of these standards with the complex mixtures of steryl chlorin esters in various recent sediments, using negative ion HPLC-MS, has confirmed the structures of a number of the natural components.

Reduction of a sulphur-rich asphaltene from a crude oil (Rozel Point) with lithium in ethylamine (Li/EtNH2) affords an alkane fraction similar to that obtained from desulphurisation with Raney nickel, but in higher yield. Using Li/EtND2, deuterium-labelled alkanes were obtained, thereby confirming the presence of sulphide linkages in the asphaltene fraction. Reduction of two sulphur-rich kerogens with similar sulphur contents, Serpiano shale (M. Triassic) and Jurf Ed Darawish (JED, U. Cretaceous) afforded significant quantities of polar solvent-extractable material. Both kerogens also yielded low amounts of hydrocarbons although the amount released from JED kerogen was significantly higher. The results indicate that, whereas the kerogens contain hydrocarbon moieties intermolecularly linked by sulphide bridges, the distributions of the precursors lipids which were incorporated were different. For example, GC-MS analysis of the labelled products from JED kerogen revealed them to be dominated by steranes of algal origin, with the position(s) of deuterium labelling providing evidence of sulphide linking and cross-linking. On the other hand, the labelled products from Serpiano kerogen were dominated by hopanes of bacterial origin which were linked terminally via the side chain.

Negative-ion liquid chromatographic-mass spectrometric analysis of the pigment composition of the bottom sediment (15–20 cm) of a eutrophic lake revealed the presence of a novel series of chlorophyll transformation products, in which a series of C 27 C 30 sterols and stanols are esterified to a pyrophaeophorbide a nucleus of algal origin. The major components are algal-derived chlorophyll a and b degradation products, and the presence of a bacteriochlorophyll-related phaeophytin indicates the presence of anoxic conditions extending into the photic zone when the sediment was laid down.

The major esterified tetrapyrrole in a Miocene oil shale (Marau, Brazil) is a free base chlorin, most likely pyrophaeophorbide a, esterified to 24-ethyl-4α-methyl-5α(H)-cholestan-3β-ol, the structure being assigned by FAB-MS and 1H NMR, and by GC-MS analysis of the sterol liberated by hydrolysis. FAB-MS and electronic absorption spectrophotometric data for the second most abundant component are consistent with the mesopyrophaeophorbide counterpart. Only one other minor esterified chlorin was detected, implying a highly specific and, hence, biologically-mediated esterification. It is not clear whether the reaction took place during biosynthesis of an unknown precursor chlorophyll or resulted from esterification of a hydrolysis product(s) from a known chlorophyll (most likely chlorophyll a) after cellular disruption, although the second possibility is considered more likely.

An unusual series of quinone pigments in a pink Eocene (c. 45x106 yr) sepiolite (quincyte, France) has been characterised by spectroscopy. The structure of the major pigment (c. 75% of total), 2,8-di-isopropyl-peri-xanthenoxanthene-4,10-quinone, was confirmed by synthesis. Spectroscopy revealed six minor related components with various oxygenated C-2 substituents (C1–C3) and, generally, a C-8 isopropyl group. Although the origin of the pigments is unknown, they (or their precursors) appear to have been biosynthesised by the acyl-malonate pathway.

The Treibs hypothesis linking sedimentary 13,15-ethanoporphins to an origin from chlorophylls requires the natural occurence of a suite of intermediates on the proposed degradative pathway. Few of the putative intermediates have been isolated and identified. Through examination of the tetrapyrrole distributions of three selected sediments, the minimum number of «intermediates» necessary for the operation of a pathway of defunctionalization has been assigned, linking a precursor such as chlorophyll a to a sedimentary porphyrin with the same carbon skeleton (deoxophylloerythroetioporphyrin). This provides further structural evidence for the defunctionalization of chlorophylls to give sedimentary 13,15-ethanoporphyrins

A C32 aetio porphyrin isolated from Gilsonite bitumen (ca. 60 × 106yr) was assigned unambiguously as aetioporphyrin—III by 1H NMR analysis of its bis[porphyrinato-mercury(II) acetato]mercury(II) complex and by comparison with an authentic sample. The occurrence of this compound provides the first direct evidence that the petroporphyrins of Gilsonite are the product of reductive degradation of naturally-occurring chlorophylls, and conversion of the chlorin to the porphyrin system.

A C 20 isoprenoid alkane (1) reported to occur in several recent sediments, has been isolated from Rozel Point crude oil and its structure confirmed by synthesis.

The high-molecular-weight constituents of the branched and cyclic hydrocarbon fraction of the Messel oil shale (Eocene) have been examined by high-resolution gas chromatography and combined gas chromatography/mass spectrometry. The following compounds are present: perhydrolycopene, together with one or more unsaturated analogs with the same skeleton; a series of 4-methylsteranes in higher abundance than their 4-desmethyl analogs; two series of pentacyclic triterpanes, one series based on the hopane structure, and the other based on the 17 alpha-H hopane structure; and an intact triterpene hop-17(21)-ene. Only two additional triterpanes were detected in minor concentrations - namely, 30-normoretane and a C31 triterpane based on the hopane/lupane-type skeleton. The presence of these compounds suggests a significant microbial contribution to the forming sediment.

A C32 and a C31 alkyl porphyrin, each present in Serpiano oil shale as the vanadyl complex, have been -isolated as the demetallated compounds and their structures determined by 1H NMR spectroscopic analysis of the zinc complexes, using selective decoupling and nuclear Overhauser effects. The occurrence of these chiral optically inactive compounds with a methyl-substituted, six membered exocyclic ring extends the known series of isomeric structural types of sedimentary alkyl porphyrins.

Three series of monoaromatic steroid hydrocarbons (basepeak = m/z 239, 253 and 267) and four series of triaromatic steroid hydrocarbons (basepeak = m/z 217, 231, 245 and 259) have been recognised by computerised gas chromatography-mass spectrometry in a variety of samples of Lower Toarcian shales from the Paris Basin. An increase in the extent of aromatisation of the monoaromatic steroid hydrocarbons in the m/z 253 series (measured by the abundance of monoaromatic components relative to triaromatic components in the m/z 231 series) is observed with increasing maturity. Variations between reported maximum burial depth and extent of aromatisation are explicable partly in terms of new maximum burial depth information for some of the shales. The extent of carbon-carbon bond cracking in the side chains of the aromatic steroid hydrocarbons has only begun to be significant in certain of the deepest samples.

The high-performance liquid chromatographic separations, on 3-μm silica, of a variety of free-base alkyl porphyrins of the type isolated from sediments and petroleums, and of a number of their acetylated counterparts, have been compared. Members of pseudohomologous series and structural isomers of both aetioporphyrins and cycloalkano porphyrins are readily separable, although the method appears to be less effective for the separation of positional isomers. Substitution of a β-methyl substituent for a β-hydrogen atom results in an increase in t R , presumably partly as a result of increased basicity. The effect of the introduction of an acetyl substituent is to shorten t R in the cycloalkano components, despite the polarity increase, but to increase t R in the aetio components. The differences in t R are explicable, therefore, in terms of an interplay between basicity and polarity, brought about by changes in the structural features of the substituents. The availability of isolated components for coinjection provides a method for routine studies of the distributions of the components of sediments and petroleums.

The kinetics of the aromatisation of both rearranged and non-rearranged monoaromatics have been investigated in the laboratory under free radical conditions. These studies have indicated that the aromatisation rate constant for the non-rearranged is greater than that for the rearranged isomers at any one particular temperature. Since the members of the rearranged series coelute with their non-rearranged counterparts when both series are present in geological extracts, these results suggest that care needs to be exercised when assessing extents of maturation using monoaromatic and triaromatic steroid hydrocarbons.

Laboratory heating experiments have been carried out using a mixture of isomeric C 27 monoaromatic steroid hydrocarbons and 6(R), 10(S) pristane as organic substrate, each on a different sediment matrix. Under free radical conditions in the presence of elemental sulphur triaromatic steroid hydrocarbons and the 6(R), 10(R) and 6(S), 10(S) isomers of pristane were formed, respectively. Both the aromatisation and isomerisation reactions follow pseudo-first-order kinetics and rate constants have been measured. A qualitative investigation of the isomerisation of 5α(H)-cholestane shows that a complex mixture of C 27 isomeric steranes is formed.

Despite their inherent low volatility, a wide range of alkyl porphyrins and their various metallo-derivatives have been successfully analysed by gas chromatography on wall coated open tubular (WCOT) capillary columns. As a result of their superior peak shape (comparable ton-alkanes of similar retention times) and relatively low Kovat's retention indices (3300–3900), the bis(trialkylsiloxy)Si(IV) derivatives offer the greatest potential for the GC analysis of geological mixtures of alkyl porphyrins. Similar derivatives of porphyrins of biomedical importance, possessing polar side chains, are also amenable to GC and GC-MS analysis.

Nuclear Overhauser enhancement 1H NMR analysis of a C31 and a C32 DPEP alkyl porphyrin from the bitumen Gilsonite (Eocene, Uinta Basin, Utah, U.S.A.) and oxidative degradation studies indicate an origin from chlorophyll a .

Chemical ionisation (CI) mass spectrometry with H 2 as reagent gas has been used to obtain spectra of a number of demetallated alkyl porphyrins from an oil shale and a bitumen. The spectra give more structural informa- tion than the electron impact spectra, by way of odd electron dipyrrolic fragment ions. Thus, the structural possibilities for a novel /c30 aetio porphyrin have been narrowed to two, although 1 H NMR only reduced the possibilities to six. The spectra of four types of components containing a five, six, seven or methyl-substituted six membered exocyclic ring show, for example, that three out of four C 32 isomers can be distinguished. The technique offers promise as a tool in structural elucidation of other novel naturally occurring porphyrins.

Backbone rearrangement of 10a(methyl)-de-A-cholest-5-ene (3c), 6-ene (3d), 9-ene (3s) and 5(10)-ene (3b) affords products isomeric at C-20 and with the C-10 methyl group in the more stable equatorial position (6a. and 6b). 5-Methylene-10a(methyl)-de-A-cholestane (5) affords similar C-20 isomeric products with both the C-5 and C-10 methyls in the more stable equatorial positions (9a and 9b). The de-A-alkenes (3) provided a convenient starting point for preparation of de-A- cholesta-5,7,9-triene (7). Components (6a, 6b, 7, 9a and 9b) have been used to confirm the widespread occurrence of homologous series of de-A-steroids in marine shales with a mild thermal history.

Detailed results are presented for the distributions of triterpenoid alkanes, acids and alcohols of the hopane family in ten samples of peat from three environments, and of contributing organisms in the case of Lyne of Skene, Scotland. Extended hopanoids of the beta alpha and alpha beta configuration appear at the very earliest stage of diagenesis. Such environments appear to be characterised by particular distributions of C32 hopanoid acids and alcohols, and a high preponderance of the C31 alpha beta hopane.

A C 31 alkyl porphyrin, occurring in an oil shale as the V=O complex, has been isolated as the free base acetylated derivative whose structure has been determined by 1 H NMR spectroscopy; the parent compound provides the first circumstantial evidence for a link between sedimentary porphyprins and chlorophyll b.

Ekweozor, CM., Okogun, J.I., Ekong, D.E.U. and Maxwell, J.R., 1981. C 24 –C 27 degraded triterpanes in Nigerian petroleum: Novel molecular markers of source/input or organic maturation? In: A.W. Rose and H. Gundlach (Editors), Geochemical Exploration 1980. J. Geochem. Explor., 15: 653–662. The analyses, by gas chromatography and gas chromatography/mass spectrometry, of the triterpane concentrate of crude oils sampled from various oil fields of the Tertiary Niger delta have revealed the ubiquitous presence of a series of C 24 –C 27 tetracyclic alkanes likely to be novel degraded triterpanes. The presence in the crude oils of a C 25 tricyclic alkane, apparently structurally related to the tetracyclanes, seemed consistent with the hypothesis of sequential cleavages of the terminal rings of precursor pentacyclic triterpenoid derivatives with increasing thermal transformation of the respective petroleums. The degraded triterpanes might be useful for assessing the stages of thermal evolution of petroleum in the reservoir. A possible application, to oil exploration, of the expected variations in the concentration of the polycyclanes in crude oils with different thermal histories would be in distinguishing primary (immature) oils from mature but bio degraded oils.

The 20R and 20S isomers of 12,14α-cyclo-12,13-seco-5α(H)-cholest-13(17)-ene and the 24-metyl homologues occur widely in deep sea sediments; their presence is further evidence for the widespread occurrence of acid catalysed rearrangements in marine sediments.

The absolute stereochemistry of pristane in a sample of contemporary marine zooplankton, Messel shale (Germany) and Djatibarang (Java) crude has been determined by gas chromatographic methods. The relative stereochemistry in Irati shale (Brazil), Green River (U.S.) crude, Halibut (Australia) crude has also been determined, and confirmed for a sample of the Green River shale. The stereoisomer distributions indicate a loss of stereospecificity of the phytol-derived 6(R), 10(S) pristane with increasing geological maturation. For example, the least mature geological sample, the Eocene Messel shale, contains solely the 6(R), 10(S) isomer, whereas a mature sample, Djatibarange crude, contains 50% of the 6(R), 10(S) isomer and 25% of each of the 6(R), 10(R) and 6(S), 10(S) isomers.

Recently developed gas chromatographic—mass spectrometric (GC-MS) and high-performance liquid chromatographic (HPLC) procedures for the analysis of petroporphyrios have been employed in the search for benzoporphyrins in six sediments, a bitumen and a petroleum. In addition, structurally assigned monobenzocycloalkanoporphyrms (benzo-CAPs) isolated from Boscan crude oil (Cretaceous, Venezuela) have been used in a co-chromatographic study of these minor components (ca. 1% of total porphyrins). The petroporphyrins are generally obtained by demetallation of metalloporphyrins from samples representing a variety of geographical locations and ages ranging from Permian (ca. 235 million years) to Palaeocene (ca. 60 million years). The data show that, where the benzo-CAPs were detected, up to 24 components can occur, although the dominant member in each case is the C33 compound. Studies of a chromatographic fraction from Boscan crude oil, enriched in high-carbon-number benzo-CAPs, indicates that the series extends from at least C30 to C38 in this sample. The GC behaviour of the benzo-CAPs as the bis(tert.-butyldimethylsiloxy)Si(IV) [(TBDMSO)2Si(IV)] derivatives is characterised by the high Kovats retention indices (ca. 3900-4300; OV-1 column). Similarly, under normal-phase HPLC conditions, the free-base benzo-CAPs elute after the major alkylporphyrins. HPLC co-chromatography of the free-bases provides a rapid means of identification of the major benzo-CAPs (C32 and C33), while the GC-MS procedure allows more detailed characterisation and quantitation of the benzo-CAP distributions as their (TBDMSO)2Si(IV) derivatives.

A significantly improved method is described for the high resolution high-performance liquid chromatographic analysis of alkyl porphyrins on 3-μm silica. This improvement has been achieved by addition of varying amounts of both acetic acid and pyridine to the mobile phase. The technique is of special value in the analysis of complex mixtures of sedimentary alkyl metalloporphyrins after demetallation, and provides a complementary method to the gas chromatographic-mass spectrometric analysis of the bis-( tert .-butyldimethylsilyl)siloxyporphyrin derivatives.

The relative stereochemistry of certain acyclic isoprenoid compounds has been determined from the following sources: two intervals from a core of bottom sediment of a eutrophic lake (Esthwaite Water, U.K.); a marshy shore sediment from a small lake on the watershed of Esthwaite; the bottom sediment of a tropical lagoon (U.S. Virgin Islands); a blue-green algal mat and its underlying reduced sediment (Shark Bay, Australia); a decayed blue-green alga (Microcystis aeruginosa) from Esthwaite Water and the products of alteration of phytol as sole carbon source by a bacterial culture from Esthwaite sediment. The stereoisomeric distributions indicate that 1. (i) in the earliest stages of diagenesis of phytol in Esthwaite sediment, reduction to the dihydrophytyl skeleton (free, esterified or bound) is biological, probably microbial, 2. (ii) by analogy with earlier studies of Esthwaite, the phytanic acid in the other sedimentary situations is compatible with an origin in phytol via biological processes; the variations in the distributions reflect the differences in the populations bringing about the conversion, 3. (iii) for the samples where 6,10,14-trimethylpentadecan-2-one was examined, the stereochemistry is compatible with an origin in phytol but no distinction can be made between the pathways of oxidation (biological or chemical), and 4. (iv) conversion of phytol by the bacterial isolate under conditions of low oxygen concentration produced 2(RS),6,10,14-trimethylpentadecan-2-ol as the major saturated alcohol; the likely route for its formation is via reduction of the corresponding ketone.

Computerised capillary gas chormatographic—mass spectrometric analysis of the petroporphyrins [as their bis( tert. -butyldimethylsiloxy)Si(VI) derivatives] of Gilsonite (an Eocene bitumen, Uinta Basin, UT, U.S.A.) has revealed 123 components in the C 26 C 36 carbon number range, demonstrating the complexity of such mixtures. Four structural classes have been recognised: (i) the A class comprising 43 components with alkyl β-pyrrole substituents (formerly aetioporphyrins), (ii) the major A-2 class (one further degree of unsaturation; 57 components) containing compounds bearing an exocyclic ring, (iii) the A-4 class (two further degrees of unsaturation; 13 components), and (iv) the A-6 class (three further degrees of unsaturation; 10 components). Co-chromatography of n -alkanes, allowing computer-aided calculation of Kovats retention indices, has enabled further classification into homologous or pseudo-homologous series. Co-chromatography of derivatised porphyrins of known structure has allowed structural assignment of 9 components; at least 24 other compounds are assumed to be structurally related to these components by extrapolation on Kovats plots.

The vanadyl porphyrins from Boscan oil (Cretaceous, W. Venezuela) were isolated as 3 fractions, and degraded to maleimides (1H-pyrrole-2,5-diones) by chromic acid. Analysis of the products by GC-MS, using multiple ion detection to enhance sensitivity, revealed a major homologous series of 3-Me components with n-alkyl side chains extending to C11, and a minor series with branched alkyl side chains, the Me branch being at C-1. The origin of the extended alkyl groups is discussed.

A C25 alkane (1) proposed previously to occur in Methanobacterium barkeri and M. thermoautotrophicum 1 and to be a sedimentary biological marker for methanogenic bacteria9, has been synthesised and its occurrence confirmed.

The first synthesis of a C-30 botryococcene has been achieved by using a modified Julia reaction for the key coupling of fragments (2) and (3). The same strategy has been used in a new synthesis of a known synthetic precursor to the entire botryococcene family.

Gas chromatographic analysis of the major isoprenoid carboxylic acids and the major ketone (6,10,14-trimethylpentadecan-2-one), derived from successive chromic acid oxidations of the kerogen of Green River Formation oil shale, indicates that their stereochemistry is compatible with the hypothesis that phytol or a derivative with the same carbon skeleton and stereochemistry was incorporated into the kerogen matrix.

Heating of C 20 (Ia) and C 28 (Ie, 20R) triaromatic steroid hydrocarbons on bentonite at 200°C results in their presumed degradation to unknown products, although traces of Δ 15 and 20S (for the C 28 compound) components were observed. No short chain, C 20 (Ia) and C 21 (Ib) triaromatics were obtained from the C 28 triaromatic. Competitive heating of equal amounts of C 20 and C 28 components showed a faster rate of degradation for the long chain homologue. This suggests that the increase in short chain triaromatics in sediments upon increasing maturation may be due to preferential degradation of the long chain homologues.

A series of 5-aryl-2H-tetrazoles, 5-aryl-2H-tetrazole-2-acetic acids, and [(4-phenyl-5-aryl-4H-1,2,4-triazol-3-yl)thio]acetic acids were synthesized and tested in vitro for superoxide scavenging activity, in vivo in the carrageenan-induced rat paw edema assay, and in the reverse passive Arthus reaction. The hydroxy-substituted compounds were effective as in vitro scavengers of superoxide but were not effective as in vivo antiinflammatory agents.

The occurrence of a C34 (131 -methyl)-13,15-ethano-132,17-prop-132(152)-eno-porphyrin (1a) in the marine serpiano oil shale suggests that metabolic transformation of chlorophyll in the fossil water column may have occurred prior to sediment incorporation.

Sedimentary C32 hopanoic acid, one of the most abundant in nature and of probable bacterial origin, has been isolated for the first time as a single component and characterized by H-1 NMR. The 17 alpha H, 21 beta H configuration of the C31 alkane has been similarly confirmed.

Recent reports have suggested the use of the relative abundances of long chain (n-C37) alken-2-ones (1, 2, and 3) in Quaternary marine sediments as a palaeoclimate indicator1. Here we report the synthesis of these ketones with all-E and all-Z stereochemistry. Use of the synthesised compounds has shown that the natural counterparts in the alga Emiliania huxleyi and in marine sediments have the unusual and unexpected E configuration.