Development of an HPLC-PDA-based analytical method for quantifying thiodipropionic acid in vegetable oil

Lipid oxidation in edible oils causes quality deterioration, necessitating effective antioxidants. Thiodipropionic acid (TDPA), an undesignated food additive in Korea, has attracted attention due to its high thermal stability. In this study, an HPLC-PDA method was developed and validated for quantifying TDPA in vegetable oils. The method demonstrated excellent specificity, linearity (R² > 0.999), sensitivity, accuracy, and precision, with detection and quantification limits of 0.44 and 1.33 μg/mL, respectively. Measurement uncertainty analysis identified the calibration curve and reference material as major contributors. TDPA was not detected in 50 commercial vegetable oil samples. Under accelerated oxidation conditions (60 °C for 12 days), TDPA retained more than 70% of its initial concentration and showed delayed yet sustained suppression of lipid oxidation compared to BHA and BHT. These results indicate that TDPA may function as a long-acting antioxidant and that the validated method is suitable for regulatory monitoring and food safety assessment.