A Laser Induced Fluorescence-Based Instrument for In-Situ Measurements of Atmospheric Formaldehyde

Direct, in situ detection of gas phase formaldehyde (HCHO) via laser induced fluorescence in a White-type multipass cell is demonstrated with a (3 sigma) limit of detection of similar to 0.051 parts per billion by volume in a 1 s sampling time. Calibration is performed in two ways: using permeation tubes and with air bubbled through an aqueous solution of HCHO. The concentration of HCHO output from the bubbler is measured by cavity ring-down spectroscopy. Measurement of ambient HCHO is carried out at the University of Wisconsin, Madison for a period of several days.