The water-soluble vitamins thiamine (B(1)), riboflavin (B(2)), pantothenic acid (B(5)), and pyridoxine (B(6)) are separated by high-performance liquid chromatography. The mobile phase, column temperature, and flow rate are optimized so that the chromatograph can be used with a Fourier-transform infrared (FTIR) detector. Reproducibility, linearity, and detection limits are evaluated for method validation. Finally, this method is successfully transferred to liquid chromatography-FTIR with a standard mixture.