The permeation coefficients of H2O and O2 through polymeric O-rings were obtained in this study. Increases of trace level impurities in an ultra-high purity nitrogen purge gas due to the permeation processes were measured using an atmospheric pressure ionization mass spectrometer (APIMS). In this paper, the experimental results of nine different O-ring samples (Kalrez, Chemraz, Teflon, Vespel, Viton) are reported. The Kalrez "wet" O-ring showed the lowest moisture permeation coefficient of 1.5×-1010 [cm3 gas(STP). cm polymer]/[cm2 polymer · sec · torr] and Vespel displayed the lowest oxygen permeation coefficient of 0.01×-1010 [cm3 gas(STP) · cm polymer]/[cm2 polymer · sec · torr] and room temperature. In addition, permeation coefficients at 50°C and 75°C are presented. The activation energies varied from about 18 to 51 kJ/mole/°K for both H2O and O2.

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