Enhanced Performance of Nafion Dryers in Removing Water from Air Samples Prior to Gas Chromatographic Analysis

Abstract

Nafion tube dryers were tested for applications of sample preparation prior to gas chromatographic analysis. Steady-state and timedependent drying efficiency were measured for four similar dryers using a 50-mL/min sample flow at 95 percent relative humidity at room temperature. A procedure was developed in which water removal efficiency was temporarily enhanced by a factor of 20 as compared with the steady state. This was accomplished by heating the dryer while purging it with a dry sample stream immediately prior to processing the gas sample of interest. The procedure was tested on an automated gas chromatographic system equipped with a cryogenic sample preconcentrator. Data for 15 volatile organic compounds of interest showed no effect of this procedure on sample integrity; some improvement in run-to-run precision was observed.