摘要
Ⅰ. INTRODUCTIONThe stable isotope label method has an important application in the fields of agriculture, biology, medical science or the like. The various label substances made by <sup>15</sup>N stable isotope can show the metabolism of each tissue within living body. The determination of stable isotope abundance is the key of this method. The classical analysis of <sup>15</sup>N abundance in ammonium is first to change the sample into N<sub>2</sub> gas by chemical reaction, then to
