Determination of ethane, pentane and isoprene in exhaled air using a multi-bed adsorbent and end-cut gas-solid chromatography.

A method for the determination of exhaled ethane, pentane and isoprene was developed and validated. The method was based on pre-concentration of the analytes on a multi-bed solid adsorbent tube containing Tenax TA, Carboxen 569 and Carboxen 1000, thermal desorption and gas chromatography (GC) with flame ionisation detection (FID). A pre-column in an end-cut GC system was used to avoid problems with water and strongly retained substances.