Paraffinic hydrocarbons in the Orgueil, Murray, Mokoia and other meteorites.

Small samples of the Orgueil (Wiik Type I), Murray (Wiik Type II), Mokoia (Wiik Type III) and other meteorites (Alais, Ivuna, Al Rais, Bells, Cold Bokkeveld, Mighei, Nogoya, Santa Cruz, Grosnaja, Kaba, Lance, Ornans, Chainpur, Karoonda, Warrenton, and St. Caprais) were extracted with organic solvents, fractionated by silica gel chromatography, and analyzed by gas chromatography and by a new gas chromatographic-mass spectrometric technique. Only the high molecular weight hydrocarbons eluted by n-heptane were analyzed. The following observations were made: All meteorites contain paraffinic hydrocarbons in varying amounts and with a certain distribution. Normal and isomeric alkanes from Cl5 to about C25 with a maximum at C19-C21 were found in the Orgueil, Murray and Mokoia meteorites. Pristane and phytane, two saturated polyisoprenoid hydrocarbons, known to be degradation products of chlorophyll, were found in all meteorites except the Ornans, although in several (Type I and Type III, except Mokoia) the amounts were very small. No predominance of odd over even carbon-number hydrocarbons was observed except in the C22-C27 normal alkane range of some samples of the Orgueil. The concentration of alkanes in certain samples of the Orgueil was found to be about one order of magnitude lower than in others indicating a significant heterogeneity in the distribution of hydrocarbons. Practically all the meteorites of Type II and some of Type III (Mokoia) gave an essentially identical or very similar hydrocarbon chromatographic pattern, indicating a common origin for the hydrocarbons. The distribution of paraffinic hydrocarbons, including pristane and phytane, in some of these meteorites was found similar to that of microfossil-bearing pre-Cambrian rocks 2 x 10(9) years old or older. The Orguiel was similar to the Gunflint chert and Type II meteorites were similar to the Soudan rock. It remains to be seen whether these hydrocarbons were formed on the earth-moon system as suggested by Urey, on the asteroids, in the solar nebula, or whether they may be the result of a unique terrestrial contamination process.