title: Hollow fiber-based liquid-phase microextraction combined with on-line sweeping for trace analysis of Strychnos alkaloids in urine by micellar electrokinetic chromatography.
abstract: A new method for the enrichment of Strychnos alkaloids in biological samples via liquid-phase microextraction (LPME) based on porous polypropylene hollow fibers combined with on-line sweeping in micellar electrokinetic chromatography (MEKC) was developed. Strychnos alkaloids were first extracted from urine sample which was adjusted to alkaline conditions (0.5 mol l(-1) NaOH). The unionized analytes were subsequently extracted into 1-octanol impregnated in the pores of hollow fibers, and then into an acidic acceptor solution (100 mmol l(-1) H3PO4) inside the hollow fiber. The extract was analyzed directly by on-line sweeping in MEKC. In the method, the compound berberine was used as the internal standard (I.S.) for the improvement of the experimental reproducibility. The calibration curve was linear over a range of 20-200 ng ml(-1) for both strychnine and brucine in human urine sample, with a correlation coefficient of 0.996 and 0.997, respectively. The detection limits (S/N=3:1) for strychnine and brucine were 1 and 2 ng ml(-1), respectively. The LPME-sweeping method has been successfully applied to the analysis of strychnine and brucine in real urine sample, indicating that LPME-sweeping-MEKC is a promising combination for analysis of basic drugs present at low levels in some biological matrices.
authors.affiliation: Key Laboratory of Bioinorganic Chemistry, College of Science, Agricultural University of Hebei, Baoding 071001, China.
authors.forename: Chun
authors.initials: C
authors.lastname: Wang
authors.forename: Cairui
authors.initials: C
authors.lastname: Li
authors.forename: Xiaohuan
authors.initials: X
authors.lastname: Zang
authors.forename: Dandan
authors.initials: D
authors.lastname: Han
authors.forename: Zhimei
authors.initials: Z
authors.lastname: Liu
authors.forename: Zhi
authors.initials: Z
authors.lastname: Wang
mesh_terms: D002138:Calibration; D020374:Chromatography, Micellar Electrokinetic Capillary / Q000379:methods*; D006801:Humans; D012015:Reference Standards; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013331:Strychnine / Q000031:analogs & derivatives* / Q000652:urine*; D031451:Strychnos / Q000737:chemistry*
chemical_list: C083806:brucine; D013331:Strychnine