title: On-line concentration sample stacking coupled with water-in-oil microemulsion electrokinetic chromatography.
abstract: This study describes for the first time, the ability of a normal stacking mode (NSM) on-line concentration step coupled with water-in-oil (W/O) microemulsion electrokinetic chromatography (MEEKC), using six common penicillin antibiotics (oxacillin, penicillin V, penicillin G, nafcillin, ampicillin, and amoxicillin) as test analytes. Optimization of penicillin separation in the conventional W/O MEEKC system demonstrated that change in the type and concentration of the oil phase (1-butanol) and column temperature had a pronounced effect on the separation. With the subsequent development of the NSM coupled with W/O MEEKC, improved separation and detection sensitivities were observed when an organic solvent plug (1-propanol; 1.04 cm) was placed between the W/O microemulsion and the sample solutions. This could be attributed to the solution viscosity difference between the aqueous sample zone and the organic solvent plug causing the penicillin to be stacked in this 1-propanol plug. The optimal NSM W/O MEEKC provided about 12-fold increase in detection sensitivity compared with conventional sample injection (50 mbar, 3 s). Finally, this proposed method was successfully applied in the analyses of several food samples (porcine organs) spiked with penicillin.
authors.affiliation: Department of Chemistry and Center for Nanotechnology at CYCU, Chung Yuan Christian University, 200 Chung Pei Road, Chung-Li, 320, Taiwan. hyhuang@cycu.edu.tw
authors.forename: Hsi-Ya
authors.initials: HY
authors.lastname: Huang
authors.forename: Wan-Ling
authors.initials: WL
authors.lastname: Liu
authors.forename: Brenda
authors.initials: B
authors.lastname: Singco
authors.forename: Shih-Huan
authors.initials: SH
authors.lastname: Hsieh
authors.forename: Yung-Han
authors.initials: YH
authors.lastname: Shih
mesh_terms: D000433:1-Propanol; D000818:Animals; D020374:Chromatography, Micellar Electrokinetic Capillary / Q000379:methods*; D004655:Emulsions / Q000737:chemistry*; D005504:Food Analysis / Q000379:methods*; D007668:Kidney; D008099:Liver; D008460:Meat / Q000032:analysis; D008956:Models, Chemical; D010406:Penicillins / Q000032:analysis; D015203:Reproducibility of Results; D013552:Swine
chemical_list: D004655:Emulsions; D010406:Penicillins; D000433:1-Propanol