The detection of xenobiotic substances in the environment is of great concern in epidemiological and toxicological studies. Low concentration and extensive metabolism of active principles could reduce the possibility to confirm the presence of this kind of analytes in sewage or river waters. The purpose of this study is to compare degradation compounds similar to those formed in oxido/reductive metabolic pathways by adopting a photocatalytic process as a model-system and afterwards to identify them in biological and environmental samples, beside parent compounds. Liquid chromatography appears to be the best technique for direct analysis of these samples (neither derivatization nor complex extraction procedure for polar compounds), together with an ion trap MSn detection that empowers diagnostic identification and metabolites characterization. LC-MS analyses were accomplished both on a ion-trap instrument and a triple quadrupole system, with electrospray interfaces. Chromatographic separation were achieved on octadecylsilica reversed phase column. Photodegradation model was applied to cocaine. Parent drug and metabolites were found and measured in real samples coming both from a toxicology laboratory (human plasma and urine) and from water treatment plants (river and sewage waters). Many oxidative potential metabolites and some hydrolysis sub-products were formed in the simulation model (cocaine photocatalytic degradation) and then identified in biological and environmental samples. MSn analysis allowed discriminating isobaric compounds with dissimilar fragmentation pathways, offering a selective determination tool.
Drugs of abuse as water contaminants: LC-MSn characterization of metabolic and environmental degradation of cocaine
GIANCOTTI, Valeria Rachele;AIGOTTI, Riccardo;CALZA, Paola;MEDANA, Claudio;BAIOCCHI, Claudio
2006-01-01
Abstract
The detection of xenobiotic substances in the environment is of great concern in epidemiological and toxicological studies. Low concentration and extensive metabolism of active principles could reduce the possibility to confirm the presence of this kind of analytes in sewage or river waters. The purpose of this study is to compare degradation compounds similar to those formed in oxido/reductive metabolic pathways by adopting a photocatalytic process as a model-system and afterwards to identify them in biological and environmental samples, beside parent compounds. Liquid chromatography appears to be the best technique for direct analysis of these samples (neither derivatization nor complex extraction procedure for polar compounds), together with an ion trap MSn detection that empowers diagnostic identification and metabolites characterization. LC-MS analyses were accomplished both on a ion-trap instrument and a triple quadrupole system, with electrospray interfaces. Chromatographic separation were achieved on octadecylsilica reversed phase column. Photodegradation model was applied to cocaine. Parent drug and metabolites were found and measured in real samples coming both from a toxicology laboratory (human plasma and urine) and from water treatment plants (river and sewage waters). Many oxidative potential metabolites and some hydrolysis sub-products were formed in the simulation model (cocaine photocatalytic degradation) and then identified in biological and environmental samples. MSn analysis allowed discriminating isobaric compounds with dissimilar fragmentation pathways, offering a selective determination tool.
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