PNNL

Abstract

Non-invasive biomonitoring for chemicals of interest in law enforcement and similar monitoring of pesticides together with their metabolites can not only save money but can lead to faster medical attention for individuals exposed to these chemicals. This study describes methods developed for the analysis of gamma-valerolactone (GVL), delta-valerolactone (DVL), acephate, and azinphos methyl in saliva and serum. Liquid chromatography/mass spectrometry (LC/MS) operated in the negative ion mode and in the positive ion mode and gas chromatography/mass spectrometry (GC/MS) were used to analyze GVL and DVL. Although both analytical techniques worked well, lower detection limits were obtained with GC/MS. The lactones and their corresponding sodium salts were spiked into both saliva and serum. The lactones were isolated from saliva or serum using newly developed extraction techniques and then subsequently analyzed using GC/MS. The sodium salts of the lactones are nonvolatile and require derivatization prior to analysis by this method. N-methyl-N-(t-butyldimethylsilyl)-trifluoroacetamide (MTBSTFA) was ultimately selected as the reagent for derivatization because the acidic conditions required for reactions with diazomethane caused the salts to undergo intramolecular cyclization to the corresponding lactones. In vitro studies were conducted using rat liver microsomes to determine other metabolites associated with these compounds. Azinphos methyl and acephate are classified as organophosphate pesticides, and are known to be cholinesterase inhibitors in humans and insects, causing neurotoxicity. For this reason they have both exposure and environmental impact implications. These compounds were spiked into serum and saliva and prepared for analysis by GC/MS. Continuation of this research would include analysis by GC/MS under positive ion mode to determine the parent ions of the unknown metabolites. Further research is planned through an in vivo analysis of the lactones and pesticides. These methodologies could be extended for further analysis of other similar compounds as well as chemical and biological warfare agents.