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

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 mu L, and for CO2 a detection limit of 19.2 mu L 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.