Abstract: An infrared fluid analyzer for the detection of end tidal CO.sub.2. The analyzer is comprised of an IR source that irradiates a chamber filled with gas. CO.sub.2 present in the chamber absorbs the IR radiation at a certain wavelength. An IR detector determines the amount of IR radiation passing through the chamber unabsorbed and produces a signal corresponding to the CO.sub.2 in the chamber. At predetermined intervals a zero gas is reintroduced into the chamber for the system to be recalibrated. A span gas is only needed initially for calibration purposes.

Abstract: The present invention pertains to an apparatus that is capable of correcting for inaccuracies caused by molecular collision broadening in analyzers. The apparatus includes an analyzer for analyzing a fluid. The analyzer is capable of producing an output signal corresponding to the fluid in the analyzer. The apparatus also includes a device for detecting molecular collision broadening in the fluid. The detecting device produces an output signal proportional to the molecular collision broadening. There is also a device for correcting inaccuracies in the analyzer output signal caused by molecular collision broadening. The correcting device is disposed to receive the analyzer output signal and the detecting device output signal, and is capable of producing an output signal corresponding thereto. Preferably, the detecting device includes a thermal conductivity cell and the correcting device is either a voltage control gain operational amplifier or a computer.