CARBONYL COLLECTION EFFICIENCY OF THE DNPH-COATED C-18 CARTRIDGE IN DRY AIR AND IN HUMID AIR

The performance of the DNPH-coated C-18 cartridge with respect to samp ling of ppb-ppm levels of carbonyls has been tested in dry air (RH = 3 -7%) and in humid air (RH = 55 +/- 10%). In humid air, experiments wit h cartridge (upstream)-impinger (downstream) sampling trains indicated no cartridge breakthrough, and good agreement was found between measu red and nominal concentrations. In dry air, there was good agreement b etween measured and nominal concentrations for ketones but not for ald ehydes. For carbonyls produced in-situ as reaction products in ozone-a lkene experiments, formation yields in dry air and humid air were the same for ketones but were lower in dry air than in humid air for aldeh ydes, especially for formaldehyde. For the ca. 20 carbonyls studied, t he results indicate good performance of the DNPH-coated C-18 cartridge when sampling carbonyls in humid air and poor performance when sampli ng aldehydes, especially formaldehyde, in very dry air. Implications o f the results are briefly discussed.