Development of a thermo desorption sensor system for the detection of residual solvents in packaging materials

Application specific sensor systems (formerly electronic noses) use static headspace for the volatile generation from condensed phase samples. This extraction method is very simple to implement, but suffers many drawbacks, i.e. in terms of efficiency or sensitivity to partitioning and is very time-consuming. To circumvent these problems, we developed a new method using dynamic extraction of volatiles (stripping). Although this method is known for GC (gas chromatography), the utilization of direct thermal desorption (DTD) in conjunction with gas sensors is quite novel. The unhandy cold trapping step can be avoided by a software integration of the instantaneous volatile concentration over the stripping time, calculated from the sensor response after a proper linearization and calibration. The estimated released residual solvents quantities from paper packaging were compared with the actual ones provided by DTD/GC-FID, and the results were found in good agreement and thus this technique can become an alternative to GC.