Urinary tract infections (UTI) are common infection diseases in the hospitals, especially for the elder people. Detecting UTI for the elder people is difficult and time-consuming procedure. Since measuring nitrite directly in urine is often employed in the diagnosis of UTI, a nitrite ion selective electrode (ISE) was investigated in this study in order to detect UTI samples directly on used diapers of patients. With a commercial ISE sensor for nitrite, the detecting system was built to quickly and precisely quantify different concentrations of nitrite ions in both water solutions and real human urine samples. Good results were shown in the experiment that the nitrite can be precisely detected in the fresh urine by the ISE with the relations as Ε=224.7-21.259×Lg (C+13.476), where E is the electrode potential and C is the concentration of nitrite ions. Besides, the method of extracting urine samples from used diapers was also studied for further research. The investigation suggested that a sampling module for used diapers could be simply realized if necessary.
