Abstract
An apparatus for ammonia (NH_3) determination by using gas permeation/gas chromatograph (GC) had been developed. The apparatus was composed of mainly GC and a thermoregulator including a permeation plate assembly for gas permeation. Urea and NH_3 in urine were determined at pH 6.5 by using the apparatus and the usefulness of the proposed method was also disscussed on the results from the measurement of both compounds. The precision of the measurement was within 6% as coefficient of variation and the detection limit was 4.5μg for the permeated NH_3. An analytical time required was within 20 min for both the compounds and the time was more than 60 min shorter in comparison with that by the both methods of the indophenol (IP) method and the urease-indophenol (UI) method. A correlations between the proposed method, and the IP method or the UI method, were also good, and their correlation coefficients were 0.98 and 0.97, respectively. But the determined values by the proposed method were slightly higher than those of the both other methods. Also, chromatographic patterns of NH_3 and total NH_3 with urine samples collected from normal and abnormal subjects were determined and compared. In comparison with their chromatographic patterns, the screening between diseases was easier and more precise in the proposed method.
