High-performance anion-exchange chromatography of human urine using perchlorate gradient elution systems

A 100-microliter volume of urine was chromatographed on a 50 X 0.4 cm I.D. column packed with a macroreticular anion-exchange resin. Elution was performed with a concave ammonium perchlorate gradient from 0 to 0.25 M at a flow-rate of 0.75 ml/min and a pressure of 7.5-11 MPa. With this perchlorate gradient, no baseline drift occurred in the detection at 254 nm, and even detection at 200 nm was possible. The effect of the addition of ethanol or acetonitrile to the ammonium perchlorate solution was investigated. For the assignment of peaks, ultraviolet spectra of the peaks were measured with stopped-flow scanning spectrophotometry.