A Single-Laboratory Validation of a UPLC Method for Determination of Folic Acid in Various Dietary Supplement Dosage Forms.

This article focuses on the development and validation of a single-laboratory ultra-performance liquid chromatography/diode-array detector (UPLC/PDA) method for determining folic acid content in various dietary supplement dosage forms, including tablets, two-piece capsules, powder drinks, softgels, and gummies. The method was validated according to AOAC INTERNATIONAL Standard Method Performance Requirements (SMPR®) 2022.002, demonstrating strong linearity, low limits of detection and quantification, good repeatability (relative standard deviation ≤4.82%), and recovery rates within 95.48–104.72% across different supplement matrices. Specificity and system suitability studies confirmed the method's accuracy and precision without interference from supplement ingredients. Overall, the UPLC/PDA method was found to be fast, reliable, and suitable for routine folic acid analysis in diverse dietary supplement forms.