Chemometrics-Enhanced High-Performance Liquid Chromatography-Diode Array Detection Strategy to Quantify Protoberberine Alkaloids in Coptidis Rhizoma-Related Medicines: Solving Overlapping Signals of Similar Spectra in Varying Sample Matrices

Abstract

Quantitative detection of bioactive protoberberine-type alkaloids in Coptidis Rhizoma (CR) is an essential guarantee for efficacy control and medication safety of related Chinese patent medicines (CPMs). However, their highly similar spectral characteristics (r=0.8849–0.9863) pose particular challenges in high-performance liquid chromatography (HPLC) separations. Traditional univariate HPLC methods limited the versatility and universal applicability of routine quality assessment. In this study, an effective strategy for simultaneous quantification of six protoberberine alkaloids was presented, processing multi-channels chromatographic-spectral data with four popular second-order calibration algorithms. Specific qualitative/quantitative information of target analytes were successfully extracted from co-eluting peaks of unexpected interferences with the additional selectivity provided by "mathematical resolution". On this basis, chromatographic conditions that can be easily performed on most conventional C18 columns were explored, and a calibration set available for CR and various complex CPMs was carefully designed. Four models were overall evaluated in terms of fit, linearity and figures of merit. Alternating trilinear decomposition assisted multivariate curve resolution (ATLD-MCR) provided the optimal performance and greater tolerance of retention time shifts between different sample matrices. The average spiked recoveries were between 98.7–106.7% with standard deviations lower than 5.4%. Statistical analysis and elliptical joint confidence region test further confirmed the reliability of the predicted results. The proposed strategy provides an alternative to avoid individual interference removal and complicated experimentally separation for varying sample matrices.

Keywords: Protoberberine-type alkaloids, Mathematical separation, High-performance liquid chromatography, Second-order calibration, Coptidis Rhizoma