Gas chromatography with ion trap detection to determine six herbicides in atmospheric samples

Abstract

Six auxin-type herbicides in air, rain and dew samples were extracted and derivatised to the volatile 2,3,4,5,6-pentafluorobenzyl derivatives, followed by confirmation and quantification using gas chromatography with ion trap detection. The extraction recovery of 2,4-dichlorophenoxyethanoic acid and its dimethylamine salt from fortified tubes (air samples), distilled water (rain samples) and filter-paper (dew samples) was acceptable. The powerful selectivity of the gas chromatograph with ion trap detection allowed quantification of the herbicides irrespective of extraneous peaks present at the same retention time. In addition, automatic confirmation was accomplished without using a mass spectrometer. For 2,4-dichlorophe-noxyethanoic acid, the method has a limit of detection of 0.72 ng m^–3 in air, 8.39 ng l^–1 in rain water and 5.21 ng per 491 cm² of exposed filter-paper (dew sample).