Determination of dinitro- and nitropyrenes in emission particulates from diesel and gasoline engine vehicles by liquid chromatography with chemiluminescence detection after precolumn reduction

Abstract

A sensitive and selective method for the determination of 1,3-dinitropyrene (1,3-DNP), 1,6-DNP, 1,8-DNP and 1-nitropyrene (1-NP) in emission particulates from diesel and gasoline engine vehicles was developed. The method consists of three steps; sample clean-up, reduction and liquid chromatographic analysis. Particulates were collected on a glass-fibre filter using a low-volume air sampler. They were extracted with benzene-ethanol and the resulting benzene phase was cleaned by extraction with sodium hydroxide, sulphuric acid and water. DNPs and 1-NP were reduced to their corresponding diaminopyrenes (DAPs) and aminopyrene (AP), respectively, by heating the extracts in the presence of sodium hydrosulphide. DAPs and AP were separated on a reversed-phase column using an imidazole buffer-acetonitrile mixture as the mobile phase. The effluent was mixed with bis(2,4,6-trichlorophenyl) oxalate-hydrogen peroxide postcolumn reagent solution and the emitted chemiluminescence was monitored. Levels of DNPs and NP as low as 10 −13 mol mg −1 were determined in emission particulates from diesel and gasoline engine vehicles using this method.