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The bacteria containing urease convert each molecule of urea into two molecules of ammonia and one molecule of carbon dioxide gas. Bacterial electrodes have been constructed by immobilizing the Proteus vulgaris on an ammonia and a carbon dioxide gas-sensors, and were investigated for the effects of pH, temperature, buffer solution, bacterial amounts and interferences, and life time. NH3-bacterial electrode based on ammonia gas-sensor had linearity in the range of 7.0 × 10-4 ∼ 3.0 × 10-2M urea in pH 7.4, 0.05M phosphate buffer at 25℃ with a slope of 116.7 mV/decade. While CO2-bacterial electrode based on carbon dioxide gas-sensor bad linearity in the range of 7.0 × 10-4 ∼ 5. 0 × 10-2M urea in pH 7.0, 0.1M phosphate buffer at 30℃ with a slope of 45.4 ∼ 45.7mV/decade. As the clinical application, urea in urine was determined by these devices and this result was compared with spectrophotometric method. Consequently, these electrodes could be used for the analysis of many samples because of simplicity, rapidity and convenience of the experimental procedure.
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