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Rapid detection of DNA damage could serve as a basis for in vitro genotoxicity screening for new organic compounds. Ultrathin films (20-40 nm) containing myoglobin or cytochrome P450(cam) and DNA grown layer-by-layer on electrodes were activated by hydrogen peroxide, and the enzyme in the film generated metabolite styrene oxide from styrene. This styrene oxide reacted with double stranded (ds)-DNA in the same film, mimicking metabolism and DNA damage in human liver. DNA damage was detected by square wave voltammetry (SWV) by using catalytic oxidation with Ru(bpy)(3)(2+) (bpy = 2,2'-bipyridine) and by monitoring the binding of Co(bpy)(3)(3+). Damaged DNA reacts more rapidly than intact ds-DNA with Ru(bpy)(3)(3+), giving SWV peaks at approximately 1 V versus SCE that grow larger with reaction time. Co(bpy)(3)(3+) binds more strongly to intact ds-DNA, and its SWV peaks at 0.04 V decreased as DNA was damaged. Little change in SWV signals was found for incubations of DNA/enzyme films with unreactive organic controls or hydrogen peroxide. Capillary electrophoresis and HPLC-MS suggested the formation of styrene oxide adducts of DNA bases under similar reaction conditions in thin films and in solution. The catalytic SWV method was more sensitive than the Co(bpy)(3)(3+) binding assay, providing multiple measurements over a 5 min reaction time.

A new, accurate, and experimentally simple method has been developed to determine dimensionless Henry's law constants using the static headspace method. The method appears applicable to a wide range of volatile and semivolatile organic compounds. Themethod worked well even for methyl tert-butyl ether (MTBE), despite its very high water solubility and hence, low Henry's law constant. The approach developed extends the usefulness of the static headspace method in obtaining real-time, accurate information for assessing environmental problems.

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Comprehensive two-dimensional gas chromatography (GC × GC) with flame ionization detection has been applied to oil spill source identification. An oil spill case from the U.S. Coast Guard's Marine Safety Laboratories (MSL) was analyzed by GC × GC. A slightly weathered, marine diesel fuel spill sample was qualitatively and quantitatively compared to two potential source samples. The high resolving power of GC × GC separated several hundred components from the petroleum matrix. Compounds of similar chemical structure were grouped together in an ordered two-dimensional chromatogram. In these ordered groups, numerous small peaks representing minor components were separated and detected. This was especially helpful in determining compounds and compound classes to be used in the analysis. Several classes of compounds were found to be useful for comparing the samples, including alkanes, cycloalkanes, alkylbenzenes, alkylnaphthalenes, and anthracene/phenanthrenes. The GC × GC analysis resulted in a match between the spill sample and one of the source samples. This result was consistent with HRGC and GC/MS analyses employed by the MSL.

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