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Infrared CO 2 analyzer error: an effect of background gas (N 2 and O 2 )

1999; American Physiological Society; Volume: 86; Issue: 2 Linguagem: Inglês

10.1152/jappl.1999.86.2.647

8750-7587

Ran Arieli, Offir Ertracht, Y. Daskalovic,

Spectroscopy and Laser Applications

Three infrared CO2 analyzers were tested for the effect of background gases: the Ametek CD-3A (Ametek, Thermox Instruments Division, Pittsburgh, PA), the Dräger Multiwarn P CO2 (Dräger, L ubeck, Germany), and the Servomex 1440 (Servomex, Crowborough, East Sussex, UK). Various CO2 concentrations were prepared with Wösthoff precision pumps (H. Wösthoff, Bochum, Germany). Calibration with a different background gas (O2 or N2) caused a similar but systematic error in the CO2 readings of all three analyzers. When the CO2 analyzers were calibrated with N2 as the background gas, the CO2 reading in an O2-enriched atmosphere was 8% lower than the true value. Conversely, calibration with O2 as the background gas resulted in a 10% overestimation of CO2 levels when N2 was the background gas. This error may be important in a few fields of respiratory physiology.