In situ derivatization/solid-phase microextraction coupled with gas chromatography/negative chemical ionization mass spectrometry for the determination of trichloroethylene metabolites in rat blood

An in situ derivatization solid-phase microextraction (SPME) method has been developed for the determination of the trichloroethylene (TCE) metabolites, trichloroacetic acid (TCA), dichloroacetic acid (DCA) and trichloroethanol (TCOH), in rat blood. The analytical procedure involves derivatization of TCA and DCA to their ethyl esters with acidic ethanol, headspace sampling using SPME, and gas chromatography/negative chemical ionization mass spectrometry (GC/NCI-MS) determination. Parameters affecting both derivatization efficiency and the headspace SPME procedure, such as the concentration of sulfuric acid, amount of ethanol, derivatization-extraction temperature and time, sample preheating time, agitator speed and desorption conditions, were optimized. The method showed good linearity over the range of 1-1000 ng/mL in rat blood for each metabolite with correlation coefficients (R(2)) higher than 0.99. The intra-day and inter-day precision and accuracy were less than 10%. The relative recoveries for all analytes were greater than 84%. Validation results demonstrated that selected ion monitoring of the (35)Cl and (37)Cl isotopes using NCI resulted in reliable and sensitive quantitation of all three TCE metabolites. This validated method was successfully applied to study the toxicokinetic behavior of TCE metabolites following a 1 mg/kg oral dose of TCE.