EFFECT OF RESIN SULFONATION ON THE RETENTION OF POLAR ORGANIC-COMPOUNDS IN SOLID-PHASE EXTRACTION

The hydrophobic nature of polymeric resins used in solid-phase extraction (SPE) often limits their efficiency by preventing intimate surface contact with aqueous samples. A polymeric resin modified by a series of chemical derivatizations with sulfuric acid was found to display excellent surface hydrophilicity and improved extraction efficiencies. The degree of sulfonation was found to play a vital role in determining the SPE efficiency of such resins. By measuring the capacity factor of several polar organic solutes in pure water, an optimum sulfonation capacity of 0.6 mequiv./g was determined. Loose sulfonated resin and Empore membranes embedded with sulfonated resin were used for SPE. Average recoveries were greater than 95% for both types of sulfonated resin for a wide variety of organic compounds including phenols, alcohols, nitro compounds, aldehydes, esters and halogenated alkanes. Breakthrough curves for p-cresol, ethyl acetoacetate, isophorone and nitrobenzene were used to compare Empore membranes embedded with sulfonated and unsulfonated resin. The sulfonated membrane yielded sharper and more efficient breakthrough for all compounds tested.