Sampling of Aldehydes and Carbonyl Compounds in Air and Their Determination by Liquid Chromatographic Techniques

Summary

A simple method for the collection of low boiling aldehydes and ketones in air has been developed. It is based on the use of small traps filled with Carbopack B adsorbent coated with suitable amounts of 2.4-Dinitrophenylhydrazine (DNPH) and H₃PO₄. Aldehydes and ketones are enriched by passing 100 to 200 L of air through the trap. After sampling, the cartridges are extracted with small volumes of CH₃CN and aliquots subjected to HPLC fractionation. Specific detection of DNPH derivatives is carried out with a UV-visible adsorbance detector set at 365 nm or by an amperometric detector working in the oxidation mode. The methods allows the determination of acetaldehyde, formaldehyde, propionaldehyde and acetone at sub-ppb levels. Typical profiles of carbonyl compounds collected in a Diesel exhaust, in urban air and in a rural area are presented. Diurnal variations of formaldehyde, acetaldehyde and acetone, occurring during a two-days photochemical smog event observed in a rural area, are reported together with the trends of ozone, PAN and toluene. The results are critically discussed.