Determination of Maize and Grain Herbicides and their Transformation Products in Soil by Use of Soil Column Extraction then Liquid Chromatography with Tandem Mass Spectrometry

A multiresidue method has been developed for identification and quantitation of the herbicides most commonly used in cultivation of maize and grain, and of their transformation products, in soil samples. The analytes were isolated by soil column extraction (SCE) and the extracts were purified by use of a Carbograph-1 cartridge. Analysis was performed by liquid chromatography coupled with tandem mass spectrometric detection (LC-TISP-MS-MS) in negative-ion mode. To optimize the extraction conditions affecting the performance of SCE, e.g. the extracting solvent used, temperature, extracting volume, and solvent flow rate, were studied. To evaluate the matrix effect in SCE, recovery experiments were performed on soil samples, with different physical and chemical characteristics, fortified with the 100 ng g−1 of the target compounds. Recovery data were satisfactory and the method detection limits were between 3 and 100 ng g−1, depending on the compound.