AN AIRCRAFT MEASUREMENT TECHNIQUE FOR FORMALDEHYDE AND SOLUBLE CARBONYL-COMPOUNDS

An aircraft technique was developed for measuring ambient concentratio ns of formaldehyde and a number of soluble carbonyl compounds, includi ng glycolaldehyde, glyoxal, methylglyoxal, glyoxylic acid, and pyruvic acid. Sampling was achieved by liquid scrubbing using a glass coil sc rubber in conjunction with an autosampler which collected 5-min integr ated liquid samples in septum-sealed vials. Analysis was performed on the ground after flight using high-performance liquid chromatography f ollowing derivatization of the carbonyl analytes with 2,4-dinitropheny lhydrazine; the limit of detection was 0.01 to 0.02 parts per billion by volume (ppbv) in the gas phase. Although lacking a real-time capabi lity, this technique offers the advantage of simultaneously measuring six carbonyl compounds, savings in space and power on the aircraft, an d a dependable ground-based analysis. This technique was deployed on t he Canadian National Research Council DHC-6 Twin Otter during the 1993 summer intensive of the North Atlantic Regional Experiment. The data obtained on August 28, 1993, during a pollutant transport episode are presented as an example of the performance and capability of this tech nique.