Reports have indicated that a metabolic byproduct of Vitamin B6 produces 4-pyridoxic acid.(1) This metabolite has fluorescent properties to could “cross-talk” with quinine (i.e., increase the fluorescent signal used for quinine and result in artificially high quinine values).(2) What techniques could we employ to separate 4-pyridoxic acid and quinine in the urine sample? This is a BSL-2 lab.