Two-step preconcentration for analysis of exhaled gas of human breath with electronic nose

The two-step preconcentrator, which performs concentrating volatile organic compounds (VOCs) and removing water vapor from samples, was suggested for the analysis of the exhaled gas of human breath. The suggested two-step preconcentrator consisted of two separate adsorbent stages, and it was operated simply by the serial adsorption/desorption of these two adsorbent stages. By using an additional adsorbent stage, the performance of water removal was improved four times without loss of the VOCs, compared with that of the conventional single-step preconcentrator. The suggested two-step preconcentrator is considered to be widely applicable to many fields in which interference by water vapor is critical. (c) 2005 Elsevier B.V. All rights reserved.