Development and Validation of Direct UV-Spectrophotometric Methods for the Analysis of Folic Acid in Bulk and Dosage Form

Folic acid (FA) is an important nutrient for several physiological functions, including DNA synthesis, amino acid homeostasis, and normal blood production. With the increased circulation of counterfeit and substandard drugs worldwide, it is vital to ensure the quality of the FA tablets using a simple and validated analytical method that can be applied for routine QC of FA tablets in developing countries or worldwide. We developed two validated spectrophotometric methods for the quantitation of FA in tablet dosage forms. The developed methods were applied to bulk and FA powdered tablets dissolved in alkaline media using a 0.1 N NaHCO₃ solution (method 1) and a 0.1 N NaHCO₃/0.1N HCl solution (method 2). The established wave lengths λ_max were found to be at 256, 283, and 366 nm (method 1) and at 295 nm (method 2). Method validation parameters included linearity, accuracy, precision, LOD, and LOQ. The accuracy and precision (RSD%) of the methods were tested by direct sample/standard comparison (n = 5) and found to be simple, selective, and robust. Good linearity was achieved, with correlation coefficients ≥0.9923 and limits of detection and quantification ranging from 1.46 to 2.44 μg/mL and from 4.45 to 7.38 μg/mL at 256, 283, and 366 nm (method 1). Likewise, the LOD and LOQ values of method 2 were 1.53 and 4.66 μg/mL, respectively. The assay results for FA tablets were 102–107% for method 1, with RSD% between 3.73 and 7.75%. For method 2, the assay results for FA tablets were 106.54 ± 2.34% with a linearity of 0.9998. These developed methods provide a simple alternative to the important published methods for assaying of FA in tablet formulations.