Measurement of uric acid in biologic fluids using an ion-exchange separation.

HE MAJOR METHODS CURRENTLY IN USE for the determination of uric cid in biologic fluids are the colorimetric (1-3), the titrimetric (4), and he enzymatic (5-7). All of these methods are performed directly on the luid to be measured and are therefore subject to the effects of interfering ubstances present in these fluids. Since the colorimetric and titrimetric echnics depend on the reducing ability of uric acid, they are nonspecific nd are susceptible to many conditions which interfere with color deelopment or iodometric titration (8, 9). In addition, intensely colored luids, such as bile, cannot be studied by these technics. The enzymaticpectrophotometric method is specific but, because of the presence of roteins, it is necessary to measure relatively small changes in absorption f ultraviolet light in the presence of very high total absorption. Initial recipitation of protein may coprecipitate a variable amount of uric cid (8). The method to be described eliminates these difficulties by first isoating the uric acid from the biologic fluid to be studied. This is achieved y ion-exchange separation. The purified uric acid may then be measured ither by the colorimetric or the enzymatic technics or simply by the