DS EN 15688:2008 Fertilizers - Determination Of Urease Inhibitor N-(N-Butyl)Thiophosphoric Triamide (Nbpt) Using High-Performance Liquid Chromatography (Hplc) Describes a method for the quantitative determination of the urease inhibitor N-(n-butyl)thiophosphoric triamide (NBPT) content in water-soluble matrices, i.e. urea based fertilizers using high perfor