Kinetic-spectrophotometric approach to the modified Berthelot procedure for serum urea determination

The results of developed kinetic-spectrophotometric method for serum urea determination by modified colorimetric Berthelot procedure were presented in this paper. To obtain high sensitivity, all reaction rates were monitored spectrophotometrically by measuring the change of absorbance with time at 700 nm. A differential variant of the tangent method was used for the processing of the kinetic data based on linear dependence of absorbance on time. The method is valid over the 0.25–2.50 µg cm−3 urea concentration interval with RSD range 8.33–2.02%. The limit of detection was calculated as 0.09 µg cm−3. The interference effects of some metal ions, anions, antibiotics, and other molecules were investigated to access the method selectivity. The method was successfully applied for the determination of urea in human quality control blood serum.