UHPLC-PDA method for monitoring catechins and caffeine in tea samples and assessment of postharvest-associated variability across multilocation samples

Herein, UHPLC coupled to a PDA-based quantification method has been developed for the simultaneous analysis of eight major catechins, namely gallocatechin, epigallocatechin, catechin, epicatechin, epigallocatechin gallate, gallocatechin gallate, epicatechin gallate, and catechin gallate, as well as caffeine. The developed method was validated using linearity studies, detection and quantification limits, accuracy studies, theoretical plate count, asymmetric factor, tailing factor, and resolution, demonstrating its reliability and efficiency for analysing the chemical composition of tea samples. To maximize overall yield, the extraction protocol was optimized by varying solvent type, extraction method, duration, and temperature variation. The developed method has been applied to investigate multilocation's and postharvest influence on caffeine and catechin content in tea leaves collected from seventeen different locations. A wide chemical diversity was observed among the samples; for example, among eight samples from Himachal Pradesh, caffeine content ranged from 13.97 to 23.25 mg/g, while catechin content ranged from 4.76 to 110.10 mg/g. Results highlighted the need for stringent protocols for post-harvest handling of unprocessed teas to avoid autooxidation during comparative analysis. Further, the developed method was applied to various marketed teas, demonstrating its efficacy for quantifying tea metabolites across diverse matrices. • UHPLC-PDA method for the simultaneous quantitative analysis of eight tea catechins and caffeine. • Method development and validation as per ICH guidelines. • Extraction procedure and solvent optimization for improved recovery. • Efficacy of the developed method for quantifying metabolites across marketed teas. • Multilocation tea leaf samples analysis to assess phytochemical variability.