Improved monitoring of halogenated organic pollutants in natural, iron containing, and bimetallic systems
Shira, Brian A.
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The now notorious pesticide, 2,2-bis (4-chlorophenyl)-1,1,1-trichloroethane (DDT), was once used widely in the US. While many sites show a marked reduction in the levels of DDT, sites associated with the manufacture of the DDT still demonstrate abnormally high levels of the compound and its metabolites. Until recently, the residues DDD and DDE were thought to be the terminal residues although other metabolites have recently been identified, namely 2,2-bis (4-chlorophenyl)-1-chloroethylene (DDMU) from DDE and dichlorobenzophenone (DBP) from DDT. Little work has been done on the identification of polar degradation products of DDT. DDA was one of the first metabolites of DDT that was isolated and it has been called ï¿½perhaps the universal DDT metabolite in microorganisms, plants, animals, and higher animalsï¿½. The goals of this study were to determine if o,pï¿½-DDA was present in river water samples, and to develop a method for the determination of the enantiomeric ratio of o,pï¿½-DDA utilizing typical environmental laboratory equipment such as a benchtop GC/MS. The limitations of other methods as well as the success of selected ion monitoring (SIM) mode detection will be discussed. Toxaphene is the name given to the complex mixture of polychlorinated bornanes of the average elemental composition C10H10Cl8 that was applied as a pesticide. Toxaphene residues have not received more attention in the environmental arena due to the complexity of the mixture present in technical toxaphene, a lack of suitable standards, and the slow development of analytical methods for detection and quantitation of toxaphene. This work reports the development of a new analytical methodology based on ESI-TOF-MS without the use of a prior chromatographic separation. Toxaphene was incubated with zero valent iron and a bimetallic system containing magnesium and palladium to reductively dechlorinate toxaphene. Results from the ESI-TOF-MS analysis are compared to GC/ECD results for homologue distribution data and to evaluate the effectiveness of the remediative schemes. The determination of the oxidation state of both oxidized and reduced cytochrome c with ESI-FTICR-MS was investigated. Through this work, it has been demonstrated that although electrochemical processes are occurring during the electrospray process, ESI-MS can preserve the oxidation state of the introduced sample.