[Simultaneous enzyme determination of C-14 glucose and C-14 fructose in human body fluids]

A new enzymatic method for simultaneous estimation of radioactivity of 1-14C-glucose and 1-14C-fructose is described. It is based on the isomerisation of 1-14C-fructose to 1-14C-glucose by phosphoglucoseisomerase (EC 5.3.1.9) and on its enzymatic removal as ribulose-5-phosphate and 14CO2. The method is specific, reproducible, and gives over 97% recoveries of glucose and fructose concentrations up to 11 mmol/1 in aquos and biological solutions.