APPLICATION OF A NOVEL 1,1'-DIMETHYLFERRICINIMUM DYE FOR THE DETERMINATION OF URIC-ACID IN URINE

Water-soluble 2-hydroxypropyl-beta-cyclodextrin (Hp-beta-CyD), a cycli c and nonreducing oligosaccharide was used to enclose a hydrophobic gu est molecule 1,1'-dimethylferrocene (DMF) to form a water-soluble yell ow complex. At high concentrations (300 mM), Hp-beta-CyD enclosed up t o 100 mM DMF. The yellow complex was electrochemically oxidized (plati num vs Ag/AgCl poised at +450 mV) to form a blue dye, 1,1'-dimethylfer ricinium (DMF(+)). This is a one-electron transfer process and the fer ricinium cation formed exhibited an absorption peak at 650 nm. The con centrated DMF(+) was stable for at least 4 mo at 4 degrees C and insen sitive to a wide pH variation (pH 2-11).