Colorimetric Carbon Dioxide Analysis
Colorimetric detectors make use of the fact that CO2
forms acidic solutions in water. Paper impregnated with an aqueous solution of a
pH sensitive dye (e.g., metacresol purple) can be maintained inside a hydrophobic
filter. When CO2
-containing gas comes into contact with the test paper,
the pH drops and the indicator changes color. Disposable devices (e.g., Easy Cap,
Nellcor Puritan Bennett, Pleasanton, CA) can analyze CO2
semi-quantitatively
and can be used to confirm tracheal intubation in the field.[163]
