title: Development of in-tube solid-phase microextraction coupled to pressure-assisted CEC and its application to the analysis of propranolol enantiomers in human urine.
abstract: A successful hyphenation of in-tube solid-phase microextraction (SPME) and pressure-assisted CEC (pCEC) was developed by installing a poly(methacrylic acid-co-ethylene glycol dimethacrylate) monolithic capillary to the six-port valve in a CEC system. The device designed was appropriate for on-line in-tube SPME coupled to pCEC or muHPLC. The evaluation of this hyphenation was first carried out for in-tube SPME-muHPLC with analytical capillaries packed with 3 microm octadecyl silica (ODS). Theobromine (TB), theophylline (TP), and caffeine (CA) were chosen as model drugs for an easy comparison with the results obtained by in tube SPME-HPLC. The detection limits of these three analytes were improved more than 100 times when compared with the direct analysis by muHPLC. Then in-tube SPME-pCEC with CEC capillaries packed with perphenylcarbamoylated beta-CD-bonded silica particles was applied to the determination and analysis of propranolol enantiomers in human urine. Under optimal extraction and separation conditions, the experimental LODs were 4 and 7 ng/mL for (S)-propranolol and (R)-propranolol, respectively. The calibration curves showed good linearity for both (S)-propranolol (R(2) = 0.9997) and (R)-propranolol (R(2) = 0.9996) over the concentration range from 20 to 5000 ng/mL. Reproducibility of the method was also investigated with intra- and interday precisions lower than 10% for both enantiomers at different concentration levels.
authors.affiliation: Department of Chemistry, Wuhan University, Wuhan, P. R. China.
authors.forename: Bo
authors.initials: B
authors.lastname: Lin
authors.forename: Ming-Ming
authors.initials: MM
authors.lastname: Zheng
authors.forename: Siu-Choon
authors.initials: SC
authors.lastname: Ng
authors.forename: Yu-Qi
authors.initials: YQ
authors.lastname: Feng
mesh_terms: D002110:Caffeine / Q000652:urine; D053801:Capillary Electrochromatography / Q000379:methods*; D011312:Pressure; D011433:Propranolol / Q000652:urine*; D052617:Solid Phase Microextraction; D013805:Theobromine / Q000652:urine; D013806:Theophylline / Q000652:urine
chemical_list: D002110:Caffeine; D011433:Propranolol; D013806:Theophylline; D013805:Theobromine