Application of enzyme/zeolite sensor for urea analysis in serum

Urea biosensor based on zeolite-adsorbed urease was applied for analysis of blood serum samples. It should be noted, that this biosensor has a number of advantages, such as simple and fast performance, the absence of toxic compounds during biosensor preparation, high reproducibility and repeatability (RSD=9% and 4%, respectively). The linear range of urea determination by using the biosensor was 0.003-0.75 mM, and the limit of urea detection was 3 μM. The method of standard addition was used for analysis of serum samples with 500-fold dilution. Total time of analysis was 10 min. Good reproducibility of urea determination in real samples was demonstrated (RSD=10%). Biosensor results were verified by using a common method of urea determination (diacetyl monoxime reaction). It was shown that by using this biosensor distinguishing healthy people from people with renal dysfunction becomes easier.