title: Simultaneous enantioseparation and sensitive detection of eight beta-blockers using capillary electrochromatography-electrospray ionization-mass spectrometry.
abstract: The feasibility of using vancomycin chiral stationary phase (CSP) and polar organic eluent is investigated for simultaneous enantioseparation of eight beta-blockers using CEC coupled to ESI mass spectrometric detection (ESI-MS). The internally tapered capillaries were utilized to pack CEC-MS columns. As compared to externally tapered columns, the use of internally tapered columns demonstrated enhanced stability, durability, and reproducibility. A mixture containing methanol/ACN/acetic acid/triethylamine at 70:30:1.6:0.2 v/v/v/v was considered as optimum mobile phase since it provided a good compromise between resolution and analysis time. As expected, sheath liquid and ESI-MS parameters mainly influenced the detection sensitivity. Interestingly, structural information of beta-blockers was available by varying the MS fragmentor voltage using in-house CID in the scan mode. In order to maximize the chiral/achiral resolution, various column-coupling approaches using teicoplanin as complementary CSP to vancomycin were tested. Several changes in the elution order of beta-blockers were observed using multimodal CSPs with some improvement in chiral or achiral resolution. The quantitative aspects of the CEC-MS method were demonstrated using R- and S-talinolol as internal standards. The calibration curves of beta-blockers showed good linearity in the range of 3-600 microM. The enantiomer of beta-blockers at a concentration of 30 nM was detectable. Furthermore, both 0.1 and 1% of the S-enantiomer could be precisely quantified in the presence of 99.9 and 99% of the R-isomer of beta-blocker.
authors.affiliation: Department of Chemistry, Center of Biotechnology and Drug Design, Georgia State University, Atlanta, 30302, USA.
authors.forename: Jack
authors.initials: J
authors.lastname: Zheng
authors.forename: Shahab A
authors.initials: SA
authors.lastname: Shamsi
mesh_terms: D000319:Adrenergic beta-Antagonists / Q000032:analysis* / Q000302:isolation & purification*; D020374:Chromatography, Micellar Electrokinetic Capillary / Q000379:methods*; D012680:Sensitivity and Specificity; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods*
chemical_list: D000319:Adrenergic beta-Antagonists