Analysis of Folic Acid in Commercial Pharmaceuticals and the Effect of Food Beverages on Its Stability

Abstract

Folic acid is essential to one-carbon metabolism and prevention of folate-responsive neural tube defects, but its quantitative determination in pharmaceutical and beverage matrices is vulnerable to matrix interference. This laboratory study measured folic acid in four commercial tablet products (coded A–D) using an indirect ferric chloride–2,2′-bipyridyl spectrophotometric assay (0.5–18 µg/mL; 520 nm) and explored five media: distilled water, diluted coffee (1:20), diluted orange juice (1:10), diluted green tea (1:10), and undiluted Seven-Up. A descriptive questionnaire was also administered to an academic convenience sample (n = 66). Apparent folic acid concentrations differed markedly between products and media. In distilled water, values ranged from 1.174 to 21.170 µg/mL. Across beverage media, measured values ranged from 3.697 to 12.109 µg/mL, but changes were non-monotonic and matrix dependent; therefore, they cannot be interpreted as degradation or bioavailability without beverage-matched calibration, recovery testing, and a stability-indicating chromatographic comparator. In the questionnaire, 78.78% had heard of folic acid, 60.60% understood its importance, 51.51% reported supplement use, and 29.16% of married respondents reported pregnancy planning. The assay is suitable for exploratory screening, but the present data do not establish pharmacopeial compliance, beverage-induced loss, or in-vivo interaction. Confirmatory analysis should use validated HPLC/UPLC with labeled-strength normalization, replicate preparations, forced-degradation specificity, and formal statistical testing.