Comparative analysis of official analytical methods for tocopheryl esters for food additive quality control.

Tocopheryl esters are widely used as nutritional fortifiers and antioxidant additives, making accurate quantification essential for regulatory compliance and quality control. However, official analytical methods differ among jurisdictions, which can cause method-dependent variability. Here, the official procedures for d-α-tocopheryl acetate, dl-α-tocopheryl acetate, and d-α-tocopheryl succinate prescribed in Korea, China, and Japan were reproduced and validated according to ICH Q2(R1). Although all methods met the criteria, sensitivity, recovery, and precision differed by analytical principle (GC-FID, HPLC-PDA, and titration). Recoveries ranged from 86.34 to 114.86% (GC-FID), 94.13-99.75% (HPLC-PDA), and 99.86-100.45% (titration), with intra-day RSD below 2.6% for all methods. Measurement uncertainty, estimated using ISO GUM and Eurachem approaches with a coverage factor k = 2, yielded expanded uncertainties (U) of 4.87-10.39%, revealing method-specific contributions from calibration, sample preparation, and repeatability. The discrepancies were linked to methodological design, underscoring the value of comparative evaluation in food additive analysis.