The fractionation/concentration of aquatic humic substances by the sequential membrane system and their characterization with mass spectrometry Available to Purchase

The sequential membrane system and electrospray ionization mass spectrometry are investigated on their usefulness for characterizing aquatic humic substances. In this research, the Suwannee River Fulvic Acid (SRFA) was used for the investigation. For the mass spectrometry, the optimum analytical conditions were determined. Two indices (i.e., the total ion intensity and the averaged molecular weight) obtained from the spectrum were found relevant for evaluating the physical characteristics of aquatic humic substances. The repetitious peaks at a discrete of 14 Da in the lower m/z range of the acquired spectrum suggested that the SRFA has the –CH₂– based structure in its lower molecular weight region. For the sequential membrane system, the optimum operating conditions were determined. The SRFA could be fractionated and concentrated by this system. The significant difference of the averaged molecular weight among the concentrated fractions from the different size membranes indicated thatthis system is useful for the fractionation and concentration of the aquatic humic substances.