Dispersive solid-phase microextraction for the UV-vis spectrophotometric determination of riboflavin (vitamin B2) in foodstuffs and pharmaceuticals.

A simple and sustainable dispersive solid-phase microextraction method was developed for the spectrophotometric determination of riboflavin (vitamin B2) at 440 nm in foodstuffs and pharmaceuticals. A new solid phase, a full biobased hydrophobic poly (3-hydroxy butyrate)-poly (lipoic acid-poly(dimethyl siloxane) graft copolymer (PHBdLipDS-UV-241), was synthesized and subsequently characterized using FTIR, 1H NMR, XPS, SEM, DSC and TGA techniques. The synthesized solid phase was found to be reusable for at least 18 cycles under the optimized conditions. The effect of matrix interferences was investigated. Limit of detection, limit of quantitation, and linear dynamic range were determined to be 0.16 μg/L, 0.53 μg/L, and 0.5-90 μg/L, respectively. The vitamin B2 contents of two standard reference materials were determined, with recovery values ranging from 94.3% to 96.0%. The proposed method was applied to foodstuffs and pharmaceuticals. The amount of vitamin B2 in the real samples were determined using analyte addition (spike-recovery) tests, yielding recoveries between 91.0% and 98.5%. Riboflavin contents of the real samples were between 0.45 and 391.3 μg/g. The amount of vitamin B2 of the analyzed samples ranged from 0.45 to 391.3 μg/g.