High-performance liquid chromatography of water-soluble vitamins. Part 3. Simultaneous determination of vitamins B1, B2, B6, B12 and C, nicotinamide and folic acid in capsule preparations by ion-pair reversed-phase high-performance liquid chromatography

Abstract

An ion-pair reversed-phase high-performance liquid chromatographic (HPLC) method for the separation and simultaneous determination of thiamine HCl (vitamin B₁), riboflavin (vitamin B₂), nicotinamide, pyridoxine HCl (vitamin B₆), cyanocobalamin (vitamin B₁₂), ascorbic acid (vitamin C) and folic acid in capsule preparations is described. The above seven active substances were extracted from the preparations within 5 min using an electronically controlled extraction apparatus. Ion-pair reversed-phase HPLC was carried out on LiChrosorb RP-18 using methanol-water-concentrated phosphoric acid-octanesulphonic acid as the eluent. All seven active ingredients were separated in less than 4 min. The detection limits were 1–2 ng for all vitamins; however, amounts of 5–10 ng were required for the quantitative HPLC determination of the vitamins. The proposed HPLC method is suitable for the determination of these active ingredients in pharmaceutical preparations such as multivitamin capsules and has a coefficient of variation between 1.1 and 3.2%. The ease of extraction, accuracy and sensitivity of the method and the time required for analysis are emphasised.