Kinetic spectrophotometric method as a new strategy for the determination of vitamin B9 in pharmaceutical and biological samples

In this study, a new method is proposed for the determination of trace amounts of folic acid (vitamin B9). This method is based on the inhibitory effect of folic acid on the reaction of Thionine and bromate in sulfuric acid media. The reaction can be monitored spectrophotometrically by measuring the decrease in absorbance at 601 nm (λmax). The effective variables on the reaction rate were investigated. Under optimum experimental conditions, the method allows to determine of the folic acid in a wide linear range with two linear segments. The limit of detection was 0.36 μg mL−1 of folic acid. Relative standard deviations of six replicate determinations of 5.0 and 50.0 μg mL−1 of folic acid were 1.18 and 1.02%, respectively. The interfering effect of the different species was also investigated. The method was evaluated by quantifying of folic acid in biological and pharmaceutical samples with satisfactory assay results.

The proposed method is based on the inhibitory effect of folic acid on the oxidation of Thionine in acidic media.Figure optionsDownload as PowerPoint slideHighlights
• Low detection limit and wide linear dynamic range.
• Possibility of the accurate and precise determination of analyte in various matrixes.
• In comparison with other methods: simple, rapid and low cost.