Chemometrics-enhanced high-performance liquid chromatography-diode array detection strategy to quantify protoberberine alkaloids in varying Coptidis Rhizoma-related medicines

•Chemometrics-enhanced HPLC-DAD strategy to quantify six protoberberine alkaloids in various matrices.•Second-order calibration provides collinearity resolution and additional selectivity for chromatography.•ATLD-MCR algorithm exhibited the optimal and stable performance for varying sample matrices.•Chromatographic condition and calibration set are universally applicable for routine assessment.•Accurate quantitation can be obtained without individual pretreatment and complex optimizations.