Determination of urinary 4-pyridoxic acid levels as 4-pyridoxic acid lactone using high-performance liquid chromatography.
A high-performance liquid chromatography method for quantitation of urinary 4-pyridoxic acid excretion is presented. Urine samples were treated with HCl to form 4-pyridoxic acid lactone. Acid-treated urine samples were diluted and analyzed by cation-exchange chromatography involving post-column alkalinization and fluorescence detection. Absence of interfering fluorescent urinary compounds was demonstrated by analyzing urine samples without lactonization and rechromatography of aliquots of 4-pyridoxic acid lactone peaks employing reverse-phase chromatography. The method is suitable for determination of urinary 4-pyridoxic acid excretion in nutritional, metabolic, and pharmacokinetic studies.
D002851:Chromatography, High Pressure Liquid; D006801:Humans; D007202:Indicators and Reagents; D007539:Isonicotinic Acids / Q000652:urine*; D011735:Pyridoxic Acid / Q000031:analogs & derivatives / Q000652:urine*
D007202:Indicators and Reagents; D007539:Isonicotinic Acids; C036509:4-pyridoxic acid lactone; D011735:Pyridoxic Acid