Solid-phase microextraction (SPME) has been directly coupled to an ion-trap mass spectrometer (MS) for the determination of the model compound lidocaine in urine, hereby applying MS/MS [fragmentation of [M + H](+) (m/z 235) to a fragment with m/z 86]. The throughput of samples has been increased using non-equilibrium SPME with polydimethylsiloxane (PDMS) fibers. The effect of temperature on the sorption and the desorption was studied. Elevated temperatures during sorption (65degreesC) and desorption (55degreesC) had a considerable influence on the speed of the extraction. The desorption was carried out with a home-made desorption chamber allowing thermostating. Only 1 min sorption and 1 min desorption were performed, after which IMS detection took place, resulting in a total analysis time of 3 min. Detection limits below 1 ng/mL could be obtained despite yields of only 2.1 and 1.5% for a 100- and a 30-mum PDMS-coated fiber, respectively. Furthermore, the determination of lidocaine in urine had acceptable reproducibilities, i.e., relative standard deviations (RSDs) below 10%. A limit of quantitation (RSD <15%) of about 1 ng/mL was obtained. No extra wash step of the extraction fiber was required after desorption if a 30-μm coating was used, whereas not all the analyte was desorbed from the 100-μm coating in a single desorption. Therefore, the SPME-MS/MS system with a 30-μm PDMS-coated fiber for rapid non-equilibrium SPME at elevated temperatures has interesting potential for high-throughput analysis of biological samples.
- solid-phase microextraction
- ion-trap mass spectrometry
- high-throughput analysis
- PERFORMANCE LIQUID-CHROMATOGRAPHY
- BIOLOGICAL SAMPLES