ISO 8603:1993

Solid fertilizers — Determination of urea nitrogen content — Gravimetric method using xanthydrol

The principle of the method specified is precipitation of the urea with xanthydrol in acetic acid solution, filtration of the dixanthylurea precipitate, drying, and weighing. This method is not applicable to fertilizers containing cyanamide or the condensation products of urea and aldehydes.