Determination of the sulfonylurea herbicides chlorsulfuron and metsulfuron-methyl in soil,water and plant material by gas chromatography of their pentafluorobenzyl derivatives

The measurement of the sulfonyl urea herbicides, chlorsulfuron and metsulfuron-methyl as pentafluorobenzyl derivatives has been investigated and the kinetics of reaction optimised. The reaction product was identified by mass spectroscopy as N,N-bis(pentafluorobenzyl)-2-chlorobenzenesulfonamide. Amounts of herbicide derivative as low as 0·1 pg per injection can be detected. Suitable conditions for both packed and capillary chromatography are given. Application of the method to residue determination is discussed and the method is shown to be suitable for residues in soil and water but less so for plant material.