Polypyrrole-coated capillary in-tube solid phase microextraction coupled with liquid chromatography-electrospray ionization mass spectrometry for the determination of β-blockers in urine and serum samples

Polypyrrole was coated on fused silica capillary's inner surface (GC precolumn) by chemical polymerization. At first, this coated capillary was used successfully for automated in-tube solid-phase microextraction (SPME) and beta-blockers' determination in urine and serum samples when coupled with liquid chromatography-electrospray ionization mass spectrometry (LC-ESI-MS). In-tube SPME is an extraction technique for analytes in aqueous samples, in which analytes are extracted from the sample directly to stationary phase (polymer coating) inside an open tubular capillary by repeated sample solution's draw-eject cycles. Compared with previous study using Omegawax 250 capillary for beta-blockers' extraction [Kataoka, H.; Narimatsu, S.; Lord, H. L.; Pawliszyn, J. Anal Chem 1999, 71, 4237-4244], polypyrrole-coated capillary showed better extraction ability fur most of compounds studied and therefore lower detection limits were achieved. The optimum extraction conditions are similar to those used for Omegawax 250 capillary. Other operating conditions are similar to our previous study [Kataoka, H.; Narimatsu, S.; Lord, H. L,; Pawliszyn, J. Anal Chem 1999, 71, 4237-4244]. beta-blockers extracted by the capillary are desorbed easily by mobile phase flow without significant carryover. Using in-tube SPME-LC-ESI-MS with selected ion monitoring, beta-blockers' calibration curves are linear from 1 to 100 ng/mL with correlation coefficients above 0.9954 (n = 24), and detection limites (S/N = 3) less than 0.1 ng/mL for most compounds. This method was successfully applied to beta-blockers' analysis in biological samples. (C) 2000 John Wiley & Sons, Inc.