Determination of vitamin B12 in multivitamin tablets by multimode high-performance liquid chromatography

Quantitative determination of vitamin B-12 in B-complex tablets was performed by using multimode high-performance liquid chromatography. The multivitamin tablets (B-1, B-6 and B-12) were sonicated for 30 min in methanol-water (50:50, v/v) and diluted to appropriated volume with the same solvent. The resulting solution was filtered and the filtrate was analysed on a phenylpropanolamine bonded silica column (15 cm x 4.6 mm I.D., 5 mu m). The optimized mobile phase was 30 mM phosphate buffer (pH 3.00) containing 6% (v/v) acetonitrile at a flow-rate of 1 ml min(-1) and the detection was measured at 361 nm. The calibration graph prepared using standards was linear from 0.05 to 0.25 mu g The determination limit was 25 ng, the relative standard deviation was 0.47% and recovery from tablet solution was 100%. An analysis was completed in 5 min. The new method is simple, rapid and precise. (C) 2000 Elsevier Science B.V. All rights reserved.