Urea is a white, crystalline solid containing 46% nitrogen. Due to its high nitrogen content, urea is the most widely used source of nitrogen for nitrogen-based fertilizers worldwide. The accurate determination of urea in urea-based fertilizers is important for regulatory and product quality purposes. This is especially true for those fertilizers in which the urea content is physically or chemically modified. Most of these fertilizer products contain some amount of free (unreacted) urea, which is a readily available nitrogen source, and as such cannot be accounted as part of the slow or controlled-release nitrogen component.
This application note demonstrates the suitability of the PerkinElmer LC 300 HPLC System for performing determination of free urea in urea-based fertilizers via AOAC Official Method 2003.14 through the analysis of five commercially available fertilizer products.