SPDE features full automation for dynamic sample extraction, desorption and analysis using the CTC Combi PAL. A gas-tight 2.5mL syringe is equipped with a special needle that is coated on the inside with an extraction phase. The phase can be applied in varying degrees of thickness. The adsorption process is best described as follows: A liquid or headspace sample is drawn up into a 2.5mL syringe, thereby adsorbing analytes onto the stationary phase. A distribution balance is reached between the liquid sample matrix and the active phase. The analytes are concentrated onto the phase by repeatedly moving the plunger up and down, thereby forcing the headspace or fluid through the needle. Fast plunger speeds ensure a quick exchange of sample near the active phase.

After adsorption, the syringe picks up carrier gas from the fiber bakeout station (if necessary, the station is also used to dry the coating and syringe). Then, the autosampler moves the syringe over to the hot GC inlet, and the analytes are desorbed. Additional gas flow from the syringe forces the analytes into the inlet, thereby ensuring sharp peak shapes. This technique can be used with splitless flow for maximum sensitivity.