Abstract: Disclosed herein is an apparatus and process for determining the vapor pressure of materials in a mixture at relatively low vapor pressures by a gas saturation procedure. The process comprises passing an inert gas over a sampled material at a controlled flow rate to create a vapor of the sampled materials that may be collected and analyzed. Of particular importance, this method and apparatus provides a means of collecting vaporized samples over an extended period of time and, therefore, allows even minor components of mixtures to be considered in the final vapor pressure analysis. The apparatus also includes a means for determining whether sampled material has progressed as vapor beyond the means of collecting the sampled material.