Determination of the herbicide isoproturon in cereal grains and pasta by LC with LC/MS confirmation

Abstract

A method was developed for the determination of the herbicide isoproturon in wheat, maize, oats and pasta, with a limit of determination of 0.05 mg kg⁻¹. Isoproturon was extracted from moistened samples using a mixture of acetone, hexane and dichloromethane. The resulting extract was cleaned-up by solid-phase extraction using aminopropyl-bonded silica cartridges and analysed by reversed-phase liquid chromatography with photodiode array detection. Confirmation was by electrospray liquid chromatography-mass spectrometry. Recoveries from seven samples of each of the four matrices spiked with isoproturon at 0.05 and 0.5 mg kg⁻¹ were in the range 88–104%. The method was used to monitor cereal grains and pasta as part of the UK food monitoring programme.

Keywords:

• cereals
• pasta
• herbicide residues
• isoproturon
• liquid chromatography
• electrospray mass spectrometry

Acknowledgements

Work was funded by the UK Ministry of Agriculture, Fisheries and Food (now part of the Department for Environment, Food and Rural Affairs) through the Pesticides Safety Directorate.