Simultaneous enantioseparation and sensitive detection of eight β‐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.

Sensitive chiral analysis by CE: An update

“…CEC was also hyphenated to ESI-MS for the chiral analysis of drugs [47,48]. In CEC, the separation was carried out mainly in a packed capillary column (PCC).…”

“…In CEC, the separation was carried out mainly in a packed capillary column (PCC). Thus, Zheng and Shamsi [47] showed the feasibility of using a vancomycin CSP for the simultaneous enantioseparation of eight bblockers by CEC-ESI-MS. Internally tapered capillaries were employed to pack CEC-MS columns (see Fig. 8A), which were fabricated by a novel procedure described by the same research group [48].…”

“…Next, data on the reproducibility of this CEC-MS system using warfarin and bblockers as model analytes were presented. Last, the applicability of performing quantitative CEC-MS with these PPCs was demonstrated for the simultaneous enantioseparation of b-blockers achieving LODs , 3610 28 M [47,48]. Figure 8B shows the sensitive detection of one enantiomer (the pharmacological active S-propranolol) at 0.1% in R-propranolol, which is the limit above which impurities have to be identified according to ICH guidelines [1].…”

Recent accomplishments in the field of enantiomer separation by CEC

“…7) [58][59][60]. Most of the recent research, however, mainly focused on the advancement of the basic understanding of the separation mechanisms [61,62], making macrocyclic antibiotic-based CEC approaches fit for practical applications by improving column (packing) technology [63,64] and investigating the MS-hyphenation capabilities of CEC [65]. TAG ( Fig.…”

“…ESI-MS detection was employed in combination with a vancomycin-based CSP (3 mm) for the simultaneous separation of eight b-blockers by CEC by Zheng et al [65]. They utilized internally tapered capillary columns (vide infra) of 75 mm id for the packing of CSP.…”