Determination of total coenzyme Q10 in seven types of dietary supplement matrices by high-performance liquid chromatography coupled with diode array detection.

An HPLC-DAD method combining selective solvent extraction and ferric chloride oxidation was validated for determining total coenzyme Q10 (CoQ10, as the sum of ubiquinone and ubiquinol) in seven distinct dietary supplement matrices, including tablets, hard- and soft-shell capsules, granules, powders, oral liquids, and gummy candies, within a single workflow. Operational reporting limits (RLs) were 3 mg/100 g for six matrices and 30 mg/100 g for soft-shell capsules, with corresponding lower limits of quantification range (LLQRs) of 10 mg/100 g and 100 mg/100 g, respectively. Spiked recoveries across all matrices ranged from 86.9 to 106.1%, with relative standard deviations (RSDs) below 5.0%. In an inter-laboratory study across six independent laboratories, analysis of a blind positive soft-shell capsule fill yielded a mean value of 19.9 g/100 g with an inter-laboratory reproducibility RSDR of 3.2%. Compared with current standards, this method eliminates multi-solvent calibrations and expands redox coverage, offering an adaptable and dependable tool for routine quality control of various CoQ10 supplements.