Abstract
Since the production and use of chemical products are performing a marked growth, the charge, for fast and efficient mechanisms of environmental pollution control and monitoring, has increased. This charge has been made even more present in the rural scenario, especially with regard to fertilizers and nitrogen compounds, which have a high pollution potential. Several methods are used to urea determination, but usually they require a pretreatment or they are unsuitable for monitoring in situ. For this reason, urea biosensor can be a fast and cost-effective analytical technique to be used in extensive monitoring programs.
Urea enzyme sensors based on potentiometric detection of ammonium ion, ammonia gas and carbon dioxide have been reported. In this study, the potential applicability of the potentiometric urea biosensor to real samples has been studied. The biocomponent used was jack beans, Canavalia ensiformis, a vegetal tissue rich in urease. The vegetal tissue was immobilized on nylon net by glutaraldehyde in order to improve the enzyme stability and the lifetime of the urea biosensor. Moreover, an ammonium ion-selective electrode was been chosen as the transducer.
The instrument was applied to commercial urea fertilizer solutions and an environmental sample, the sugar-cane vinasse. The linear concentration range calibration curve was 1–20 ppm urea with a response time of 15 min. Urea biosensor could be reused for 70 days and the response was more than 95 % reproducible. Moreover, the urea biosensor was tested in real samples with qualitative promising responses.
