QUANTIFICATION OF AMMONIA IN HUMAN BREATH BY THE SELECTED-ION FLOW TUBE ANALYTICAL METHOD USING H3O-2(+) PRECURSOR IONS( AND O)

We show how our selected ion Bow tube mass spectrometric technique for trace gas analysis can be used to determine the concentrations of amm onia in alveolar breath from single exhalations using both H3O+ and O- 2(+) precursor ions for chemical ionization. Thus, data are presented of the alveolar ammonia concentrations in the breath of six healthy vo lunteers following the ingestion of a liquid protein meal, which show that consistent values are obtained using these two precursor ions. Al veolar breath ammonia concentrations (which range from 200 to 1750 ppb in these individuals) are compared with those obtained from bag sampl es of breath from the same individuals. (C) 1998 John Wiley & Sons, Lt d.