Determination of total coenzyme Q₁₀ in seven types of dietary supplement matrices by high-performance liquid...

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 RSD_R 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.