DIN EN 16651:2015-07

This European Standard specifies a method for the quantitative determination of the urease inhibitors N-(n-Butyl)thiophosphoric acid triamide (NBPT) and N-(n-Propyl)thiophosphoric acid triamide (NPPT) content in urea based fertilizers using high-performance liquid chromatography (HPLC). For quantitative calibration, pure NBPT or NPPT reference material is used as a standard. Urease inhibitors are added to fertilizers in order to control the release and effect of nutrients in the soil in a targeted manner; that is, for example, long-term effects and thus increase nutrient efficiency. This in turn serves the goal of using as few chemical fertilizers as possible with good crop yields. The transfer of nitrogen in the form of nitrate into soil, groundwater and crops can be reduced by the use of urease inhibitors. NBPT/NPPT (traded under the name LIMUS as an additive to urea-based fertilizers) is a newly developed urease inhibitor for the determination of which in fertilizers a validated determination procedure is presented for the first time with this European standard. The method was validated under German project management in a Europe-wide collaborative trial with eleven participating laboratories. The statistical data are provided in the informative Annex A. The European Standard has been prepared by Technical Committee CEN/TC 260 "Fertilizers and liming materials" (secretariat: DIN). The national mirror committee is Working Committee NA 057-03-02 AA "Düngemittel" ("Fertilizers") at DIN Standards Committee Food and Agricultural Products (NAL).