AOAC RI ERP EBOOK FOR FERTILIZERS

Conclusions The AOAC Official Methods 959.03 (Urease Method) and 983.01 (HPLC Method) are frequently inaccurate and therefore not suitable for measuring the amounts of free and unreacted urea in liquid urea-formaldehyde condensate products. AOAC Official Method 2003.14 consistently provides more accurate analytical results for measuring the contents of free urea in these classes of fertilizers. Acknowledgements We give special thanks to Hugh Rodriguez, Thornton Laboratory, Tampa, FL, and John Hartshorn, Morral Chemical Co., Morral, OH, for collaborative support of this study. We are also indebted to Nancy Thiex and James Bartos for many helpful suggestions.