The present paper describes a method for the fluorometric determination of
uric acid in blood serum by its reaction with uricase (UOx). The procedure
is based on the changes in fluorescence that take place during the enzymati
c reaction of UOx with uric acid when the solution is excited at 287 nm and
the emission is measured at 330 nm. A mathematical model which relates the
analytical signal to the analyte concentration was developed and the model
also served to obtain some of the thermodynamic constants of the system (t
he Michaelis constant and the turnover number). The optimum reaction condit
ions and its analytical characteristics were studied, linear response range
(3 x 10(-5)-6 x 10(-4) M) and reproducibility (4%, n = 7). The method was
applied to the determination of uric acid in three blood serum samples. The
results were compared with those obtained by a commercial clinical analyze
r and no systematic errors were observed. (C) 2001 Elsevier Science B.V. Al
l rights reserved.