Determination of difenzoquat in cereals by GC/MS

An analytical method by GC/MS has been established for the herbicide difenz oquat in cereals. Difenzoquat was extracted with acetone, concentrated with a rotary evaporator, and applied to an Extrelut 20 column. The column was washed with n-hexane, eluted with ethyl acetate containing 4% formic acid, and concentrated. The residue was dissolved in 0.1 mol/L NaOH solution, ads orbed on an ODS mini column, washed with 50% methanol, and eluted with ethy l acetate containing 4% formic acid. The elute was concentrated and analyze d by GC/MS. This method gave a recovery of over 80% with a C.V. below 6% an d a detection limit of 1 mu g/kg. This method, with excellent sensitivity a nd selectivity, should be useful as a routine analytical method for cereals .