A spectrophotometric method for determining the amount of folic acid in fortified salt

Analytical methods for quantifying and monitoring the degradation of micronutrients added to food are crucial to food fortification programs. In the case of folic acid in fortified salts, there are difficulties in developing an effective analytical method due to interference of salt in the standard HPLC methods, as salt precipitates in the HPLC column. To circumvent the problem, a spectrophotometric method was developed to quantify folic acid and monitor its degradation in salt. A distinct absorption wavelength was selected for folic acid in sodium carbonate solution. Of the three wavelengths where maximum absorption was observed for folic acid, 285 nm was selected as being selective for folic acid in the presence of pteroic acid, glutamic acid, aminobenzoic acid, and other products of degradation of folic acid. The method was calibrated for 1-25 μg/mL folic acid (R² = 1). The recovery was 100 ± 1.2% and 100 ± 1.8% for folic acid in salt and solution, respectively. The limit of detection and quantification for this method is 0.011 μg/mL and 0.033 μg/mL, respectively. The method is accurate, precise, and selective for folic acid in the presence of potential products of folic acid degradation, and is suitable for monitoring folic acid degradation in fortified salt.