Dynamic drying and sampling set-up allowing to remove water from fresh plant material prior to thermal desorption-gas...

Fresh plant material can contain a high amount of water, sometimes even more than 30 %. This often hampers the analysis of the volatile compounds by gas chromatography (GC). So, a novel dynamic drying and sampling set-up based on thermal desorption (TD) prior to GC was developed and optimized. This study aimed to reduce the water content and to maximally protect the original volatiles in the fresh plant material for analysis. The method involved three sequential tubes with sample, desiccant and sorbent, respectively, offering effective performance for absorbing water and collecting volatiles. Key parameters such as heating temperature and sweep gas volume (gas flow multiplied by heating time) were systematically optimized to maximize analyte transfer efficiency. Comparative analysis with headspace-GC revealed superior recovery and reduced water content for the new approach. Method development was performed using defrosted rosemary. Next, the proposed method was applied to fresh plants, including also thyme and mint. Further, the developed approach can also distinguish between plants from natural and polluted sources due to the variation in chemicals which could be found in a traffic-contaminated environment.