Simultaneous determination of water-soluble vitamins excreted in human urine after eating an overdose of vitamin pills by a HPLC method coupled with a solid phase extraction.

We have applied a quick and convenient method for determining water-soluble vitamins excreted in human urine. We found that the Sep-Pak C(18) cartridge was useful for preconcentration and recovery of water-soluble vitamins in urine with minimized loss of vitamins. The recovery of vitamins was well over 90%. The separation was carried out by gradient elution with 90/10 (v/v%) methanol/water with 0.1% trifluoroacetic acid (TFA) and water with 0.1% TFA on a muBondapak C(18) column. The separation was completed within 15 min. We measured concentrations of water-soluble vitamins excreted in urine after swallowing an overdose of vitamin pills on purpose, and found that the concentration of each vitamin increased rapidly to the maximum in 2-3 h and decreased swiftly.