Real-Time Monitoring of Fragrance Release from Cotton Towels by Low Thermal Mass Gas Chromatography Using a Longitudinally Modulating Cryogenic System for Headspace Sampling and Injection

摘要

An innovative headspace sampling and injection systemnfor gas chromatography was designed using a longitudi-nnally modulating cryogenic system mounted around thensampling loop of a two-position loop injector. The setupnwas hyphenated to a fast low thermal mass gas chromato-ngraph, allowing transient concentrations of semivolatilenanalytes to be monitored in real time with a time resolu-ntion of 4.5 min. The performance of the instrument, andnin particular its cryotrapping efficiency, was characterizednusing a mixture of long-chain alkanes, methyl esters, ethylnesters, and alcohols of different volatilities. The device wasnfound to be ideally suited to the analysis of semivolatilencompounds with boiling points ranging between 190 andn320 °C, which are typical for a majority of perfumery rawnmaterials. The new instrument was successfully used tonmonitor the release of eight odorant compounds fromncotton towels to which fabric softener had been appliednthat alternatively contained the fragrance in free form ornin microencapsulated form. The analytical results, un-nprecedented in their level of precision and time resolutionnfor such an application, evidenced the major impact ofnmicroencapsulation technology on the kinetics of fra-ngrance release during the drying of the towels and on thentriggering of additional fragrance release by applyingnmechanical stress to the fabric to rupture the microcap-nsule walls.