Abstract:

A simple, rapid, accurate and sensitive method of solid-phase extraction and ion-pair RP-HPLC was developed for the determination of folic acid (FA) in health food products. Solid-phase extraction (SPE) was performed to enrich FA extracted using a Chromabond-SB cartridge with strong anion exchange material. The addition of tetra-n-butylammonium, as an ion-pairing reagent, from samples was found to significantly increase the retention time of FA, thus leading to a well shaped and clearly separated single peak. The analysis was performed on a Lu-Na C18 column (5 μm, 250 mm×4.6 mm) using a mobile phase composed of 0.05 mol/L KH2PO4 solution, 0.01mol/L tetra-n-butylammonium and acetonitrile (88:2:10, V/V, pH 5.5) at a flow rate of 1 ml/min, with the UV detection set at 284 nm. In the range of 0.06－2.40 μg/ml, a good linear relationship between peak area and FA concentration was found, and the correlation coefficient and the LOD were 0.9996 and 0.008 μg/ml, respectively. The spike recoveries for FA in three commercial health food products ranged from 95.14% to 102.87%.

Key words: solid-phase extraction, HPLC, health food products, folic acid