An instrument to mass spectrometrically analyze volatile compounds trapped or formed in an intractable solid matrix such as a polymer or resin‐fiber composite is described. Samples are precisely abraded inside the ion‐source housing of a time‐of‐flight mass spectrometer, and the evolved compounds are mass analyzed. By use of appropriate data acquisition and analysis techniques, either qualitative or quantitative information about the indigenous volatile compounds can be obtained. In the latter case, distribution profiles of the trapped compound(s) can be measured. Typical results for water in an epoxy resin and the pertinent experimental variables in obtaining accurate distribution profiles are discussed.