Development of a methodology for the determination of carbon monoxide using a quartz crystal microbalance

Abstract

Starting from a method published in the literature for the determination of CO by a quartz crystal microbalance, important changes were made in order to solve the principal analytical problems found, as well to simplify the analytical procedure in order to become a general methodology. The new methodology allows quantitative determination of both CO and CO₂. Sensitivity for CO is governed by its conversion to CO₂ by silver oxide, which depends on the dimension of the Ag₂O column percolated by the gas. Detection limit for CO, using a crystal coated with tetramethylammonium fluoride with an amount corresponding to a frequency decrease of 18.7 kHz was 7.7 µL, and for CO₂ a detection limit of 19.2 µL was found, using a crystal with a coating amount that produced a frequency decrease of 13.6 kHz. A sample of the exhaust gas of a car was analysed and the results compared with the ones obtained by non-dispersive infrared spectrometry.