Urinary excretion of xanthurenic acid and zinc in diabetes: 1) Separation of xanthurenic acid-Zn2+ complex by ion-exchange chromatography.

In view of the relevance of urinary xanthurenic acid (XA) and zinc in diabetes, a chromatographic procedure has been devised which allows separation of XA from its complex with Zn2+. The procedure involves chromatography on DEAE-Sepharose CL-6B at pH 7.2 with a stepwise Tris-HCl concentration gradient. The ultraviolet absorption difference spectra due to formation of the XA-Zn2+ complex allowed the estimate of the binding molar ratio in the XA-Zn2+ complex. This corresponds to a 1:1 as estimated on the basis of the Hill plot of the experimental data.