Characterization of fulvic acid by Fourier transform ion cyclotron resonance mass spectrometry

Fulvic acid is a heterogeneous mixture that has many roles in the chemistry and geochemistry of natural environments. In this report the application of laser desorption (LD) ionization and ESI to the mass spectrometric analysis of FA is presented. The mass spectrometry studies reported here were performed on Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometers which are capable of ultra-high resolution and sensitivity. Desorption wavelength was found to significantly affect the laser desorption Fourier-transform mass spectrometry of fulvic acid. At infrared desorption wavelengths (10.6;Electrospray ionization studies resulted in the highest positive-ion mass-to-charge distributions ever observed for FA by mass spectrometry (1000-2400Da). Solution conditions were found to affect the mass-to-charge distributions for the ions as well as the ability to detect the ions. Evaluation of solution conditions determined that the optimum spray conditions for these samples was a 70% H...