General description of filter techniques

Principle:

1. Sorption of analyte(s) from air A to sorbent material P in the filter: volumes up to several hundred m³ air are sucked through one filter by high volume sampler
   
   
   
   Note: This is an expression for partition equilibrium (note: non-equilibrium conditions prevail if flow rates are too high to allow attainment of local equilibrium for analyte(s) between the air and the sorbent phases)
   
   
2. Thermal desorption of analyte from sorbent in an oven coupled to a GC system