Absorptiometric determination of monolinuron in herbicide formulations

Abstract

The method described depends on the hydrolysis of monolinuron in boiling 4 N hydrochloric acid to yield p-chloroaniline. A portion of the diluted solution is treated with sodium nitrite and the diazotised p-chloroaniline coupled with 1-naphthol in alkaline solution to give a red colour, the optical density being measured at 500 nm. The colour develops immediately and is stable, thus permitting the use of differential absorptiometry. The method has been satisfactorily applied to technical samples and monolinuron formulations, with an error of 0·8 per cent.