Abstract: Apparatus is disclosed for pre-treating and spectrally analyzing a sample of matter, including a structure for promoting reaction of an analyte to produce characteristic effects of the analyte measurable by an optical analysis device. The structure defines a sheltered region for containing the analyte, a support surface within the region for supporting a filtering medium, an exposure path for exposing the analyte to an energy source and an optical path leading out of the sheltered region along which radiation characteristic of a property of the analyte proceeds to the optical analysis device.