However, breath testing is technically difficult be-Breath testing for volatile organic compounds cause most breath VOCs are excreted in nanomolar (VOCs) provides an intrinsically safe method for in-(10 09 M) or picomolar (10 012 M) concentrations. Since vestigating human metabolism. An improved breaththese levels are too low for detection by most instrucollecting apparatus (BCA) is described which was acmentation, breath VOCs must be concentrated prior to ceptable to patients, simple to use, highly sensitive, assay. This, in turn, requires special apparatus for the and free from chemical contamination. VOCs in 10.0 L collection and concentration of breath. Several ad hoc alveolar breath and 10.0 L room air were collected onto methods have been described, utilizing cold trapping adsorptive traps. Using automated instrumentation, (18), adsorptive binding (19), and chemical trapping VOCs were thermally desorbed and assayed by gas (19) to capture the VOCs in the breath while allowing chromatography/mass spectroscopy. Twenty normal the free passage of the nitrogen and oxygen (1).
volunteers were studied, and the alveolar gradient
Progress in breath testing has been limited by the (concentration in breath minus concentration in air) lack of generally accepted and standardized methodolwas determined for the most abundant VOCs. A total ogy for the collection and analysis of breath VOCs. This of 1259 VOCs were observed and tentatively identified report describes a new breath-collecting apparatus in the breath of normal subjects. The mean alveolar (BCA) which was developed from an earlier prototype gradients were positive in 461 VOCs and negative in (2). The BCA is portable and ''user-friendly,'' and pro-798 VOCs. The method provided a sensitive and convevides samples which can be analyzed by standard assay nient assay for breath VOCs and permitted tentative techniques. determination of their origin from either inside or outside the body. α§ 1997 Academic Press MATERIALS AND METHODS device. Hospitalized patients, including some who were 272