Amperometric Enzyme-based Gas Sensor for Formaldehyde: Impact of Possible Interferences

In this work, cross-sensitivities and environmental influences on the sensitivityand the functionality of an enzyme-based amperometric sensor system for the directdetection of formaldehyde from the gas phase are studied. The sensor shows a linearresponse curve for formaldehyde in the tested range (0 - 15 vppm) with a sensitivity of1.9 μA/ppm and a detection limit of about 130 ppb. Cross-sensitivities by environmentalgases like CO₂, CO, NO, H₂, and vapors of organic solvents like methanol and ethanol areevaluated as well as temperature and humidity influences on the sensor system. The sensorshowed neither significant signal to CO, H₂, methanol or ethanol nor to variations in thehumidity of the test gas. As expected, temperature variations had the biggest influence onthe sensor sensitivity with variations in the sensor signal of up to 10 % of the signal for 5vppm CH₂O in the range of 25 - 30 °C.