A non-adsorptive method for the isolation and fractionation of natural dissolved organic carbon

A non-adsorptive method was rested for the concentration and fractionation of dissolved organic carbon (DOG) in groundwater. Reverse osmosis combined with ultrafiltration recovered more than 90% of the DOC and efficiently separated the DOC into three size fractions. Unlike adsorptive methods, this procedure avoids the use of strong acids and bases that may alter the structure of the DOG. A diafiltration method was applied during ultrafiltration that gave good separation of the DOC into high-, medium-, and low-molecular-size fractions. The high- and medium-molecular-size fractions are desalted during this fractionation procedure and can be further analyzed for individual compounds. The inorganic solutes remain in the low-molecular-size fraction. Future advances in ultrafiltration membrane technology may facilitate removal of inorganic ions without significant loss of low-molecular-size organic acids. Studies on a synthetic groundwater showed that the combined reverse osmosis/ultrafiltration method is viable for the concentration and fractionation of a wide range in organic compounds typically found in groundwater. Copyright (C) 1996 Published by Elsevier Science Ltd.