Enantioselective column coupled electrophoresis employing large bore capillaries hyphenated with tandem mass spectrometry for ultra‐trace determination of chiral compounds in complex real samples

Abstract

A new multidimensional analytical approach for the ultra-trace determination of target chiral compounds in unpretreated complex real samples was developed in this work. The proposed analytical system provided high orthogonality due to on-line combination of three different methods (separation mechanisms), i.e. (1) isotachophoresis (ITP), (2) chiral capillary zone electrophoresis (chiral CZE), and (3) triple quadrupole mass spectrometry (QqQ MS). The ITP step, performed in a large bore capillary (800 μm), was utilized for the effective sample pretreatment (preconcentration and matrix clean-up) in a large injection volume (1-10 μL) enabling to obtain as low as ca. 80 pg/mL limits of detection for the target enantiomers in urine matrices. In the chiral CZE step, the different chiral selectors (neutral, ionizable, and permanently charged cyclodextrins) and buffer systems were tested in terms of enantioselectivity and influence on the MS detection response. The performance parameters of the optimized ITP - chiral CZE-QqQ MS method were evaluated according to the FDA guidance for bioanalytical method validation. Successful validation and application (enantioselective monitoring of renally eliminated pheniramine and its metabolite in human urine) highlighted great potential of this chiral approach in advanced enantioselective biomedical applications.

Challenges and applications of isotachophoresis coupled to mass spectrometry: A review

“…(A) ITP/chiral CE‐MS setup used by Piešťanský et al. in several publications [79–81]. The upper part depicts the ITP column with TE vial and LE vial.…”

“…The close‐up shows the arrangement of electrolyte and SL components. Reprinted from [81] with permission from John Wiley & Sons. (B) ITP/CE‐MS analysis of pheniramine (PHM) and phenylephrine (PHE) spiked to human urine using heart cutting.…”

“…The group stressed the excellent sensitivity of their method compared to ITP/ITP due to higher MS compatibility of the BGE. Detection and quantification limits were in the low to medium ng/L range for pharmaceuticals [79–81]. Exemplarily, Fig.…”

Recent contributions for improving sensitivity in chiral CE

“…As it is shown in Table , during the period the time covered by this review only three in‐capillary sample preconcentration approaches have been employed to improve the sensitivity in chiral analysis using CE with UV detection, field‐amplified sample injection (FASI), sweeping, and a combination of FASI and sweeping. Other approaches such as ITP stacking and field‐amplified sample stacking have also been used, but in combination with the detection of MS (see Table ), which are described in Section .…”

“…A new multidimensional analytical approach for the ultratrace determination of pheniramine enantiomers in human urine was reported by Piestansky et al. . In this work, the authors modified a commercial coupled column CE system for online combination of ITP stacking with the chiral EKC separation and its direct connection to a triple quadrupole mass spectrometer.…”