Abstract: A method and infrared sensing device for determining the concentration of alveolar alcohol in a breath sample exhaled by a subject into an infrared sensing device. The presence of alcohol from the upper respiratory tract of the subject is detected by continuously monitoring alcohol and carbon dioxide, normalizing alcohol values with respect to carbon dioxide, calculating a difference between normalized alcohol concentration and carbon dioxide concentration over time, integrating (summing) the difference, and comparing the integrated difference with a threshold. This technique accurately and consistently detects the presence of mouth alcohol in the sample before the presence of carbon dioxide which originates in deep lung breath.

Abstract: An analyte detection system for non-invasively determining the concentration of an analyte in a sample is described. The detection system includes a window assembly consisting of a main layer adapted to allow electromagnetic radiation to pass therethrough, and a heater layer adapted to exchange heat to the sample. The system also includes a detector adapted to detect electromagnetic radiation emitted by the sample and passed through the window assembly. The analyte detection system also includes a control system in electrical communication with the heater layer and adapted to cause the heater layer to exchange heat to the sample. The main layer of the window assembly may be made from a variety of materials such as germanium, silicon, and chemical vapor deposited diamond.

Abstract: A method and infrared sensing device for determining the concentration of alveolar alcohol in a breath sample exhaled by a subject into an infrared sensing device. The presence of alcohol from the upper respiratory tract of the subject is detected by continuously monitoring alcohol and carbon dioxide, normalizing alcohol values with respect to carbon dioxide, calculating a difference between normalized alcohol concentration and carbon dioxide concentration over time, integrating (summing) the difference, and comparing the integrated difference with a threshold. This technique accurately and consistently detects the presence of mouth alcohol in the sample before the presence of carbon dioxide which originates in deep lung breath.