CONSTRUCTION AND PERFORMANCE OF A GAS PURGE SYSTEM

The construction of a gas purge system for measurement of sorption kin etics is described in detail. The system features continuous monitorin g of gas-phase organic compounds using a photoionization detector, bot h open and closed modes of operation, and a convenient flask-switching design. Detector response was found to be adversely affected by small fluctuations in gas Bow rate and by electrical interference from the temperature control system. Modification of the initial design incorpo rates flow control within the detector loop and uses a proportional te mperature controller. Dynamic measurements of Henry's Law constants in the gas purge system are reproducible and agree with literature value s for most of the organic compounds tested.