AN ARTIFACT IN AIR CARBONYLS SAMPLING USING C-18 DNPH-COATED CARTRIDGE

A sampling artifact is observed when collecting carbonyl compounds in ambient air using 2,4-dinitrophenylhydrazine (DNPH)-coated C-18 cartri dges. While lower carbonyls (C-1-C-4) are not significantly affected, ca. 80% of C-5-C-8 carbonyl concentrations are due to artifact formati on. Furthermore, several high molecular weight carbonyls, containing u p to 18 carbons, were artificially produced during sampling probably d ue to reactions between ambient ozone and C-18 sorbent matrix. The use of ozone trap is recommended for carbonyls sampling with DNPH-coated solid sorbents. The most suitable sampling system is a DNPH-coated sil ica gel cartridge connected to an upstream crystalline KI trap. (C) 19 98 Elsevier Science B.V.