Measurement of Aldehydes Using DNPH Derivatization and Water Impinger Methods

摘要

Determination of aldehydes in ambient air as well as industrial stacks is receiving increased attention because of the critical role these compounds play in tropospheric organic chemistry; including ozone formation and photochemical smog. Aldehydes and ketones are sampled using DNPH derivatization methods (EPA 0011, TO-11A, and CARB 430) as well as water impinger methods (NCASI 99.02). The acrolein chemistry associated with derivatization is complex because of the tautomerization of its hydrazone in acidified DNPH solution. In this investigation, the problems associated with the unsaturated carbonyls, i.e. acrolein, sampling and analysis are addressed in terms of equilibrium chemistry and instability of its DNPH derivative. However, the addition of extraction solvent (toluene) during sampling improved the recovery of acrolein. This study was further extended to validate water impinger sampling methods (NCASI 99.02) for carbonyls, and our lab experiments show that carbonyls, including acrolein, show excellent recovery.