James Claude Carnahan

Polychlorinated Biphenyl Dechlorination in Aquatic Sediments

The polychlorinated biphenyl (PCB) residues in the aquatic sediments from six PCB spill sites showed changes in PCB isomer and homolog (congener) distribution that indicated the occurrence of reductive dechlorination. The PCB dechlorinations exhibited several distinct congener selection patterns that indicated mediation by several different localized populations of anaerobic microorganisms. The higher (more heavily chlorinated) PCB congeners that were preferentially attacked by the observed dechlorination processes included all those that are either pharmacologically active or persistent in higher animals. All the lower (less heavily chlorinated) PCB congeners formed by the dechlorinations were species that are known to be oxidatively biodegradable by the bacteria of aerobic environments.

Comprehensive, quantitative, congener-specific analyses of eight aroclors and complete PCB congener assignments on DB-1 capillary GC columns

Abstract We have determined complete polychlorinated biphenyl (PCB) congener assignments and weight percent distributions for all major (> 0.5 wt %) PCB components of Aroclors 1221, 1232, 1242, 1016, 1248, 1254, 1260, 1262 that are resolved by DB-1 (polydimethylsiloxane) capillary GC columns. Aroclor components present between 0.05 and 0.5 wt % were also identified but not quantified. Quantitation was done using a combination of GC-ELCD (Hall electrolytic conductivity detector) and GC-MS measurements. All 209 PCB congeners have been assigned to the 124 peaks that can be resolved on DB-1 columns. The data support use of these eight Aroclors individually or in customized standards for calibrating the comprehensive, quantitative, congener-specific PCB analyses that are necessary for accurate quantitation of the complex and often radically altered mixtures of PCBs typically found in the environment.

A study of copper oxide catalysts used in the methylchorosilane reaction and determination of the fate of oxygen

The relative effectiveness of CuO and Cu2O were compared as catalysts for the methylchlorosilane (MCS) reaction. MCS reactions catalyzed by CuO had higher rates (0.15 g/g Si-h) than MCS reactions catalyzed by Cu2O (0.08) AND higher selectivities (4–5 points in % Di higherfor CuO). A synthetic method was found for making 17O-labeledCu2O based on reaction of CuCl with excess NaCl and >2equivalents of Na17OH. The Na17OH was made from17O-enriched water and Na. The % enrichment of theCu2O was determined by reduction of the Cu2O with H2 to form Cu and water and then subsequent reaction of the water product with Me2SiCl2 to make cyclo-octamethyltetrasiloxane (D4). The 17O enrichment of the D4 wasthen determined by mass spectroscopy. Thus Cu2O was made with27% 17O ±5%. The labeled Cu2Owas used as the catalyst in the MCS lab reactor. A 14% enrichmentin 17O in D4 and dichlorotetramethyldisiloxane(MClMCl) was found vs. the controlexperiment with natural abundance oxygen Cu2O. Thus all of the oxygen from the copper oxide catalyst ends up as siloxane; 50% of the oxygen in the product siloxane comes from other sources. Copper oxide catalyst was used in the presence of the phosphorus promoters Cu3P and PEt3. In both phosphorus promoter experiments, the resultant MCS lab beds were subjected toacetonitrile extraction and then NMR analysis of the extracts. Theseextracts showed that phosphorus-containing species were present and thatwhen Cu3P was the promoter, phosphorus products containing17O were present. Thus for Cu3P, some of thephosphorus reacts with the 17O from the Cu2O catalyst.

Levels of bioactive PCDF congeners in PCB dielectric fluids from capacitors and transformers

Abstract The levels of three pharmacologically active PCDF congeners, namely the 2,3,7,8,-tetra-, 2,3,4,7,8-penta-, and 1,2,3,7,8,9-hexachlorodibenzofurans, were measured by a precise two-dimensional gas chromatographic mass spectrometric procedure in PCB dielectric fluids taken from both used and unused capacitors and transformers, as well as in Aroclor standards. It was found that the electrical uses did not cause increases in bioactive PCDF levels.