Development of the continuous monitoring method of blood ammonia

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An attempt was made to develop a method to determine blood ammonia concentration continuously. As the sensor for ammonia detection, lr-Pd MOS diode was constructed, which showed a linear voltage change of 200 mV for 0-15 ppm change in ammonia. An another diode ammonia sensor (TGS # 814D by Figaro) was also tested which showed a lineality between 0-80 ppm. In addition, ammonia gas glass electrode which uses polytetrafluoro-ethylene as an ammonia permeable membrane showed wide range of lineality of electrode output, i.e. 0.1 -20 mM. Because the electrode system has advantages that it is usable for both gas and liquid and that modification of housing is easy, this system was used for further analyses.This system to measure ammonia concentration continuously was applied for the detection of blood urea, for which urease was immobilized to spherical cellulose gel with diameter of 50 m and packed in 70 1 of chamber. Blood was perfumed through the chamber and the increase of ammonia concentration was used for the detection of blood urea concentration, and the system gave highly significant correlation between the emf of the electrode and log of urea concentration between 0.1 and 100 mM. This system was successfully applied for the continuous monitoring of blood, urea concentration during hemodialysis of a patient was kidney disorder.These results suggests that the system developed in this study is applicable for the automated control of hemodialysis of patients with kidney disfunction and also for the monitoring of sanitary condition in confined space such as space craft.