In vivo studies on the long‐term persistence of volatiles in the breath

The long‐term persistence of five volatiles in the breath was studied to determine the effects of respiration and the physical properties of each of the volatiles. The long‐term persistence of each of the volatiles in the breath was modelled successfully and used to show that the breath volatile concentration 1 min after consuming the solution was greater when panelists exhaled at a slower rate. The air–water partition coefficient ( K aw ) was influential in controlling the initial stages of persistence; compounds with a higher K aw were found to decay at a much faster rate than compounds with a low K aw . The decay rate during the later stages was constant for all the volatiles, which indicates that the rate‐limiting factor during the later stages of persistence does not depend on the individual properties of the volatiles.