DETERMINATION OF BARBITURATES BY SOLID-PHASE MICROEXTRACTION (SPME) AND ION-TRAP GAS-CHROMATOGRAPHY MASS-SPECTROMETRY

Solid-phase microextraction (SPME) in conjunction with quadrupole ion trap GC-MS was applied to the determination of a series of barbiturate s. A 65 mu m Carbowax-divinylbenzene (DVB) SPME fiber was used to succ essfully extract a series of eight barbiturates from aqueous solution. Absorption kinetics and distribution coefficients for the 65 mu m Car bowax-DVB SPME fiber were determined for the compounds. In addition th e method was evaluated with respect to linearity, limit of detection, precision, desorption time, and the effect of salt. Limits of detectio n reached 1 ng/ml for the barbiturates. Linearity was established for the barbiturates over a concentration range of 10-1000 ng/ml, with coe fficients of correlation 0.99. Overall, the precision of the method fe ll between 2.2%-6.5%, depending on the barbiturate. SPME was applied t o the identification and quantitation of the barbiturates in a urine m atrix. The method was validated by analyzing a reference standard pent obarbital-spiked urine sample. Both standard addition and internal sta ndard with [H-2(5)]-pentobarbital techniques were evaluated, with reco veries found to be 93% and 104%, respectively. SPME was then used to r apidly screen a urine specimen tested positive for barbiturates, and b utalbital was detected and quantified. (C) 1997 Elsevier Science B.V.