Extraction of intrinsic column peak profiles of narrow-bore and microbore columns by peak deconvolution methods.

The intrinsic peak profiles (free from the delay and dispersion caused by state-of-the art UHPLC systems) generated by narrow-bore and microbore chromatographic columns used in liquid chromatography-mass spectrometry (LC-MS) proteomic analyses are extracted from two different deconvolution methods. The first method is based on the classical discrete Fourier transform (DFT) while the second method refers to the Taylor expansion of the continuous Fourier transform (FT). The two numerical methods are compared regarding the accurate determination of the intrinsic peak profiles of the non-retained compound (toluene) expected on a narrow-bore 2.1 mm × 100 mm column packed with 1.6 µm CORTECS-C18 superficially porous particles and installed on three different LC systems (ACQUITY i-class UPLC, ACQUITY H-class UPLC, and Arc LC systems). The DFT-based method is most relevant when the low-frequency band of the chromatographic peak does not overlap with the high-frequency bands related to the experimental baseline noise (pump/detector). The Taylor expansion-based method is successful for the extraction of the intrinsic peak profiles of narrow-bore 2.1 mm i.d. columns packed with sub-2 µm particles installed on standard UHPLC systems. When the LC system dispersion significantly exceeds that of the column, the DFT-based method is preferred over the Taylor expansion-based method and is successfully applied to extract the intrinsic peak profiles generated by a microbore 1.0 mm × 100 mm column packed with 1.8 µm HSS-C18 fully porous particles (volume variance ∼ 0.15 µL2 for the non-retained compound toluene) run on the low-dispersion ACQUITY i-class UPLC system (∼ 1 µL2 volume variance). This result opens up promising avenues for the development, quality control, and LC-MS analyses of microbore 1 mm i.d. columns using the state-of-the-art UHPLC instruments at flow rates larger than 0.1 mL/min.

Mass spectrometry detection of basic drugs in fast chiral analyses with vancomycin stationary phases / 药物分析学报

Current trends in chiral analysis of pharmaceutical drugs are focused on faster separations and higher separation efficiencies. Core-shell or superficially porous particles (SPP) based chiral stationary phases (CSPs) provide reduced analysis times while maintaining high column efficiencies and sensitivity. In this study, mobile phase conditions suitable for chiral analyses with electrospray ionization LC-MS were systematically investigated using vancomycin as a representative CSP. The performance of a 2.7 μm SPP based vancomycin CSP (SPP-V) 10 cm × 0.21 cm column was compared to that of a corresponding 5 μm fully porous particles based analogue column. The results demonstrated that the SPP-V column provides higher efficiencies, 2–5 time greater sensitivity and shorter analysis time for a set of 22 basic pharma-ceutical drugs. The SPP-V was successfully applied for the analysis of the degradation products of racemic citalopram whose enantiomers could be selectively identified by MS.