Emissions of Carbonyl Compounds from Vehicles Fuelled with Different Gasolines

Abstract

Carbonyl compounds (formaldehyde, acetaldehyde, acrolein, benzaldehyde and acetone) were sampled using Sep-Pak DNPH-Silica cartridges placed inside the exhaust pipes of several cars using various fuels; some of the cars were equipped with catalytic converters. The DNPH-hydrazones formed were analysed by high-performance liquid chromatography. Formaldehyde was the major compound found most often in the exhaust gases, both with hot and cold engines, although sometimes acetaldehyde was the major compound in exhaust from cold engines. Concentrations of the other substances tested for were markedly lower. With a cold engine, those vehicles with or without a catalytic converter and fuelled with 98-octane unleaded gasoline had the high est levels of carbonyl compounds in their emissions: converters do not work efficiently under these conditions. Vehicles without catalytic converters and using super leaded or gas oil (diesel) had lower levels of emissions. When the engine was warmed up and fuelled with 98-octane unleaded gasoline, formal dehyde concentrations in the exhaust gases increased in two types of cars; concentrations of the other carbonyl compounds decreased when a catalytic converter was present, but increased without. Using super leaded or gas oil in a warmed-up engine (without a catalytic converter), the amount of formalde hyde also increased, although that of the other compounds did not change much. Diesel cars emitted the lowest levels of carbonyl compounds. However, all vehicles can contribute to an increase in outdoor and indoor levels of these compounds, especially those of formaldehyde, in air.