Liquid chromatography/mass spectrometry of the thermally labile herbicides, chlorsulfuron and sulfometuron methyl

Abstract

An on-line liquid chromatographic/mass spectrometric technique with direct liquid introduction (DLI) was investigated for the analysis of chlorsulfuron, the active ingredient of Glean® herbicide and sulfometuron methyl, the active ingredient of Oust® herbicide. These compounds are thermally labile and cannot be analysed by gas chromatography. Our work reported here demonstrates that with DLI-liquid chromatography/mass spectrometry (LC/MS) we can eliminate thermal decomposition and obtain a mass spectrum with complete fragmentation pattern and abundant protonated molecular ion. The amount of fragmentation and abundance of the protonated molecular ion can be changed by varying the source pressure or temperature. This effect is valuable for identification and quantification purposes. In addition, the study includes a comparison of chlorsulfuron spectra obtained by both DLI-LC/MS and commercial thermospray LC/MS interface.