A prototype model low level carbon monoxide analyzer was developed using fluorescent cell and negative chopping techniques to achieve a device superior to state of art NDIR (Nondispersive infrared) analyzers in stability and cross-sensitivity to other gaseous species. It is clear that this type of analyzer has that capacity. The prototype analyzer, which is a self-contained unit powered from 115V 60HZ line, showed an ultimate detectivity to CO of approximately 1 ppm. and no measurable cross sensitivity to any other gaseous species at the level normally found in the ambient atmosphere. The theory and results of the research are summarized. (NTIS)