Compound-Specific Sulfur Isotope Analysis of Petroleum Gases.

We describe a simple, sensitive, and robust method for sulfur isotope ratio (S/S) analysis of ppm-level organic sulfur compounds (OSCs) in the presence of percent-level HS. The method uses a gas chromatograph (GC) coupled with a multicollector inductively coupled plasma mass spectrometer (MC-ICPMS). The GC, equipped with a gas inlet and a valve that transfers the HS to a thermal conductivity detector (TCD), enables a precise heart cut and prevents the saturation of the MC-ICPMS.

Measurement of 13C and 15N isotopic composition on nanomolar quantities of C and N.

We describe a trapping and chromatography system that cryogenically removes CO(2) and N(2) generated from sample combustion in an elemental analyzer (EA) and introduces these gases into a low-flow helium carrier stream for isotopic analysis. The sample size required for measurement by this system (termed nano-EA/IRMS) is almost 3 orders of magnitude less than conventional EA analyses and fills an important niche in the range of analytical isotopic methods. Only 25 nmol of N and 41 nmol of C are needed to achieve 1.

Methane-producing microbial community in a coal bed of the Illinois basin.

A series of molecular and geochemical studies were performed to study microbial, coal bed methane formation in the eastern Illinois Basin. Results suggest that organic matter is biodegraded to simple molecules, such as H(2) and CO(2), which fuel methanogenesis and the generation of large coal bed methane reserves. Small-subunit rRNA analysis of both the in situ microbial community and highly purified, methanogenic enrichments indicated that Methanocorpusculum is the dominant genus.