2.4. Breakthrough Test

The above described preconcentrator was mounted on the set-up showed in Figure 4. The 5 mL/min of an equimolar 1 ppm BTEX mixture diluted in nitrogen (Air Products SAS, Aubervilliers, France) flowed through the preconcentration unit. This concentration was too high to be analyzed by a standard gas chromatograph (µBTEX-1 In’Air Solutions, Strasbourg, France) equipped with a 200 µL sampling loop. Therefore, the gas stream from the preconcentrator outlet was diluted prior to the analysis using an additional flow of 95 mL/min of nitrogen (99.999% purity, Messer, Folschviller, France) to avoid saturation of the gas chromatograph detector. The whole diluted gas stream was connected directly to the chromatograph sampling loop which was constantly renewed. Every 11 min, the content of the sampling loop was injected into the separation column and analyzed.

Schematic drawing of set-up used for breakthrough experiments.