Determination of Folic Acid by Ultra-High Performance Liquid Chromatography in Certain Malt-based Beverages after Solid-Phase Extraction

The aim of the present work was to develop and validate an efficient Ultra-High Performance Liquid Chromatography (UHPLC) method for the determination of folic acid (FA) in malt-based beverages. Solid-phase extraction (SPE) procedure was used for cleanup and preconcentration of the malt-based beverages before the UHPLC analysis. The analysis was performed in a C18 column (2.1x50 mmx1.8 µm) using a solvent system of ACN: 0.1 % formic acid in water (10:90, v/v) by isocratic elution. Injection volume was 5 µL. The flow rates of the mobile phase were maintained at 0.2 mL min ‒1 for 0.00–4.00 min and 0.5 mL min ‒1 for 4.01–12.00 min. Methyl paraben was used as the internal standard (IS). The FA and IS signals were detected at 284 nm and 254 nm, respectively. Under these conditions, FA and IS were separated in 3.6 min and 11.4 min, respectively. The method was successfully validated in terms of precision, accuracy, linearity, limits of detection (LOD) and quantification (LOQ) parameters. The relative standard deviations for intra- and inter-day precision were less than 1.5%. Good linearity with a high correlation coefficient was achieved over the concentration range of 20.13 µg L −1 – 2004 µg mL −1 for FA. The LOD and LOQ values were 6.66 µg L −1 and 20.13 µg L −1 , respectively . Good recovery values were found ranged between 99.1% and 106% for boza and vitamin fortified malt drink. The proposed method was successfully applied for the determination of FA in malt beers, vitamin fortified malt drinks and boza samples.