HPLC Determination of Water-soluble Vitamins in Multi-vitamin Pills

Sample of multi-vitamin pills was dissolved in 0.01 mol·L-1 HCl,and the solution in a definite volume was filtered with 0.45 μm filtering membrane and used for HPLC analysis.The Dikma C18 column was used as stationary phase,and solutions of 0.1 mol·L-1 KH2PO4 (adjusted to pH 3.5 with H3PO4) containing 1% by volume of acetonitrile mixed with acetonitrile-H2O(6+4) solution in different ratios were used as mobile phase in the gradient elution.UV-detection was used in the determination.Linearity between values of peak area and concentration of 6 water soluble vitamins,namely vitamin B1,vitamin C,vitamin B6,nicotinamide,calcium pantothenate,and vitamin B2,were proved by linear regression analysis,giving correlation coefficients over 0.999 9.Detection limits (3S/N) found for these vitamins were in the range of 0.1 to 0.3 mg·L-1.Precision of the method was tested by 6 determination of the same sample,giving values of RSD′s (n=6) of 2.0%,2.2%,1.8%,2.8%,4.7% and 1.5% for the 6 vitamins respectively.Recovery was tested by standard addition method,results of average recovery found for the 6 vitamins were 98.1%,108.7%,101.8%,99.7%,105.7% and 92.7% respectively.