Since the discovery of HP (Helicobacter pylori) and its close association with gastritis and peptic ulceration, it has been important to establish a practical method for conveniently testing HP infection. Because of the strong urease activity of HP, the urea administered orally is broken down into NH3 and CO2 by the HP urease in the patient's stomach. Then the NH3 is absorbed by the blood and excreted in the urine. The HP infection can be detected with15N — tracing method,15NH
excretion test, using15N — urea as a tracer compound. Performing on the detection with a optical spectrometer made by us for measuring the15N — abundance in the urine is reported.A group of 24 patients was detected. The results are accurate and similar to microbiological tests. The optical spectrometer is cheaper, simpler and more convenient to operate than a mass spectrometer in measuring15N abundance. Using the optical instrument, the15NH
excretion test could be widely used in hospitals.