Rapid determination of thiamine, riboflavin, niacinamide, pantothenic acid, pyridoxine, folic acid and ascorbic acid in Vitamins with Minerals Tablets by high-performance liquid chromatography with diode array detector

A simple, isocratic, and stability-indicating high-performance liquid chromatography (HPLC) method has been developed for the rapid determination of thiamine (VB1), niacinamide (VB3), pyridoxine (VB6), ascorbic acid (VC), pantothenic acid (VB5), riboflavin (VB2) and folic acid (VB9) in Vitamins with Minerals Tablets (VMT). An Alltima C18 column (250 mm × 4.6 mm i.d., 5 μm) was used for the separation at ambient temperature, with 50 mM ammonium dihydrogen phosphate (adjusting with phosphoric acid to pH 3.0) and acetonitrile as the mobile phase at the flow rate of 0.5 ml min−1. VB1, VB3, VB6, VC and VB5 were extracted with a solution containing 0.05% phosphoric acid (v/v) and 0.3% sodium thiosulfate (w/v), and were then simultaneously analyzed by using the mobile phase of phosphate buffer-acetonitrile (95:5, v/v), while VB2 and VB9 were extracted with a solution containing 0.5% ammonium hydroxide solution (v/v), and were then simultaneously analyzed by using the mobile phase of phosphate buffer-acetonitrile (85:15, v/v). The detection wavelengths were 275 nm for VB1, VB3, VB6, VC, 210 nm for VB5, and 282 nm for VB2 and VB9. The method showed good system suitability, sensitivity, linearity, specificity, precision, stability and accuracy. All the seven water-soluble vitamins were well separated from other ingredients and degradation products. Method comparison indicated good concordance between the developed method and the USP method. The developed method was reliable and convenient for the rapid determination of VB1, VB3, VB6, VC, VB5, VB2 and VB9 in VMT.