Array of potentiometric sensors for multicomponent analysis of blood serum

Two urea biosensors, based on carboxylated polyvinylchloride ammonium ion selective electrodes with urease immobilized with carbodiimide, were included in an array together with potassium and sodium ion selective electrodes and evaluated for simultaneous determination of urea and potassium in blood serum. The results show that it is possible to obtain principal component regression and partial least squares (PLS2) calibration models for simultaneous determination of urea (in the range 0.10-5 mM) and potassium (in the range 0.20-0.60 mM) based on a set of 9 calibration samples. The prediction errors of the concentration of urea and potassium in blood serum samples using this array and a PLS2 calibration model are lower than 13 and 5%, respectively.