A Detailed Molecular Characterization of High Organic Content Liquids Used in Agriculture.

Little is known about the composition of various types of high organic content liquids (HOCL) available for agricultural use. In an attempt to better understand HOCL, we analyzed two HOCLs, a standard humic acid and a material prepared by Actagro called HOCL-879. Currently, HOCL’s are characterized by their total carbon, humic acid and organic matter content which tells us little about their composition. Alternatively, fourier transform ion cyclotron resonance mass spectrometry (FTICR-MS) is a high resolution technique from which precise masses and by extension molecular formulae can be obtained. A comparative analysis of a standard humic acid and new commercial product using FTICR-MS in four different modes, laser desorption ionization negative (LDI neg), laser desorption ionization positive (LDI pos), electrospray ionization negative (ESI neg) and electrospray ionization positive (ESI pos) was conducted to determine differences within the two HOCLs. The data sets were processed using Compass data analysis software which was able to populate molecular formulae for each individual set of data and from the molecular formulae, Van-Krevelen plots were generated to help classify the types of organic molecules within the products as well as to provide a characteristic molecular fingerprint. We think this method may be an improvement on existing methods to characterize liquid agricultural supplements.