Bertocchi P, Compagnone D, Palleschi G
Dipartimento di Scienze e Tecnologie Chimiche, Università di Roma Tor Vergata, Italy.
Biosens Bioelectron. 1996;11(1-2):1-10. doi: 10.1016/0956-5663(96)83708-0.
Amperometric enzyme probes for ammonium and urea have been assembled and evaluated using immobilized glutamate dehydrogenase and urease enzymes coupled with platinum electrodes. Analytical parameters such as pH, buffer, temperature, probe life-time, enzyme immobilization, cofactor concentration and response time have been optimized. Ammonium was detected in the range 10(-5)-3 x 10(-4) mol l-1. Better reproducibility and stability were achieved using the enzyme GLDH type III and NADH at a concentration of 10(-3) mol l-1. Urea has been determined in the range 10(-5)-3 x 10(-4) mol l(-1) using the enzyme urease first in solution and then immobilized on nylon net. The analysis was based on an amperometric measurement which gives a linear relationship between current and analyte concentration. This considerably improved the sensitivity of the analysis when compared with the potentiometric-based procedures. Moreover, this method does not suffer from the potassium ion interference which affects the potentiometric nonactin-based NH+4 electrodes. Analysis of ammonium and urea were carried out in standard solutions and in saliva samples. Results compared with a spectrophotometric reference procedure correlated well.
已使用固定化谷氨酸脱氢酶和脲酶与铂电极相结合的方法组装并评估了用于铵和尿素的安培型酶探针。对诸如pH值、缓冲液、温度、探针寿命、酶固定化、辅因子浓度和响应时间等分析参数进行了优化。铵的检测范围为10(-5)-3×10(-4) mol l-1。使用III型GLDH酶和浓度为10(-3) mol l-1的NADH可实现更好的重现性和稳定性。首先在溶液中使用脲酶，然后将其固定在尼龙网上，已测定尿素的范围为10(-5)-3×10(-4) mol l(-1)。该分析基于安培测量，电流与分析物浓度之间呈线性关系。与基于电位法的程序相比，这大大提高了分析的灵敏度。此外，该方法不受影响基于非actin的电位法NH+4电极的钾离子干扰。在标准溶液和唾液样品中进行了铵和尿素的分析。与分光光度参考程序相比的结果相关性良好。
