Accelerated solid-phase dynamic extraction of toluene from air.

Solid-phase dynamic extraction (SPDE) belongs to the most innovative sample preparation and enrichment techniques. However, there is still a lack of knowledge on the fundamentals of SPDE and its applicability in the field of environmental monitoring. A homemade sampling device is constructed to make a detailed study of SPDE kinetics for toluene extraction. It proved that at least 50 aspirating and dispensing cycles were necessary to obtain toluene equilibration between gas and coating phase. A mechanistic model is proposed to explain that in every dispensing step during SPDE, significant losses of retained analytes (up to 48%) occur due to desorption processes. A new accelerated solid-phase dynamic extraction procedure (ASPDE) has been developed that avoids dispensing stages during extraction. The resulting extraction time proves to be 1.7 min, being a reduction by a factor of 37 compared with the SPDE extraction time. ASPDE proved to have high potential in ambient/indoor air monitoring. The limit of detection for toluene was determined to be 56 ppb(v), i.e. a factor of respectively, 6 and 35 lower than obtained with SPME and conventional headspace sampling with gas syringe.