System and method for breath sampling and breath analysis

A system and method for breath analysis. The system includes an exhaled gas sampling device configured to collect a substance sample from exhaled gas of a detection subject; and a sample preparation device configured to extract a selected analyte from the collected substance sample. The expiration analysis method comprises the following steps: placing the sampling disc near an expiration port of a detector; receiving exhaled gas on the sampling tray for a predetermined time, such as about 1 hour; collecting a sample of substances from the exhaled gas by adsorption on the sampling tray wherein the number and composition of adsorbed substances correspond to the average number and composition of substances exhaled over a period of time; putting the sampling disc with the collected substances into a desorption container; releasing the collected substance from the sampling tray in a desorption container by heating in an inert atmosphere; preparing a sample by adsorbing the selected analyte in the sample of substan