QUANTITATIVE EXTRACTION OF LINEAR ALKYLBENZENESULFONATES USING SUPERCRITICAL CARBON-DIOXIDE AND A SIMPLE DEVICE FOR ADDING MODIFIERS

Quantitative extraction of anionic surfactants, linear alkylbenzenesulfonates (LAS), from soil, sediment, and municipal wastewater treatment sludge was achieved using a simple apparatus for the preparation of high concentrations of organic modifiers in supercritical CO2. The method allows several different modifiers to be tested without the necessity of mixing modifiers in the pump or purchasing pre-mixed fluids. Of the several modifiers tested, methanol yielded the best extraction efficiencies, and > 90% recoveries of LAS were achieved using a 30-min extraction at 380 atm with ca. 40 mol % methanol in CO2. Extraction efficiency versus time plots for C-14-labeled and native LAS showed good agreement, indicating that the spiked LAS was representative of the native LAS.