Multivariate approach for the enantioselective analysis in micellar electrokinetic chromatography-mass spectrometry. I. Simultaneous optimization of binaphthyl derivatives in negative ion mode.

A mixture of two molecular micelles polysodium N-undecenoxy carbonyl-L-leucinate, (poly-L-SUCL) and polysodium N-undecanoyl leucylvalinate, (poly-L-SULV) was utilized in micellar electrokinetic chromatography-electrospray ionization-mass spectrometry (MEKC-ESI-MS) to simultaneously separate and detect enantiomers of binaphthyl derivatives. Separation parameters such as background buffer composition, voltage, temperature, and nebulizer pressure were optimized using a multivariate central composite design (CCD). Baseline enantioseparation for both analytes was achieved. The CCD was also used in the optimization of sheath liquid and spray chamber parameters to achieve optimum ESI-MS response. The results demonstrate that CCD is a powerful tool for the optimization of MEKC-MS parameters and the response surface model analysis can provide in-depth statistical understandings of the significant factors required to achieve maximum enantioresolution and ESI-MS sensitivity.