FLUOROMETRIC ASSAY FOR UREA IN URINE, PLASMA, AND TUBULAR FLUID

Simple and sensitive two-step fluorometric assays for urea in microliter and nanoliter samples of biologic fluid are presented. Urea was reacted with urease to release ammonia. The ammonia produced was combined with a pthalaldehyde-mercaptoethanol reagent at pH 7.4 to produce a stable fluorescent product. The fluorescence of unknowns and urea standards were measured using a filter fluorometer and compared. Fluorescent intensity of the reaction product varied linearly with urea concentration over a wide range (0-50 mm) for both microliter and nanoliter samples. Recovery of urea when added to urine or plasma was complete. © 1979.