Trapping solvent during film formation

Influenee skin formation. The aim is to produee a homogeneous eure when the paint or varnish film hardens wifliout the formation of a stable surface film during the drying period. The correct composition of the solvent will avoid trapping solvents under the surface film. 

The recovery of volatile analytes by partial concurrent solvent evaporation was significantly improved by using a volatile desorption solvent (e.g. methyl acetate). This allowed a low transfer temperature to be used and the addition of a presolvent to ensure the early formation of a solvent film to enhance solvent trapping [77,117]. The concentration of analytes in the initial portion of the desorption solvent is high and falls to a low level or zero at the completion of the desorption process. The early escape of weakly trapped volatile analytes deposited at the front of the solvent film, where the analyte concentration is highest, is the main cause of their low recovery. Volatile analytes poorly trapped by the solvent film in the retention gap are transported through the gas phase faster than the front of the solvent film advances during solvent transfer. 

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