Liquid-Solid Disk Extraction Followed by SFE and GC-Ion-Trap MS for the Determination of Trace Organic Pollutants in Water

The U.S. Environmental Protection Agency’s (EPA) Industrial Toxic 33–50 Program, which is part of the Pollution Prevention Act of 1990, outlines a plan to reduce the use of some commonly used liquid solvents. One of the most widely used solvents for extraction of organic contaminants in water and wastewater is methylene chloride, which is targeted for reduction. An alternative sample preparation technique utilizing liquid-solid disk extraction followed by supercritical fluid elution (SFE) is developed to replace the methylene chloride liquid-liquid extraction technique. Water samples containing 43 semivolatile organic analytes are first passed through 47-mm diameter Empore C18 disks (J.T. Baker; Phillipsburg, NJ or Varian; San Fernando, CA). The analytes are then eluted from the disks with supercritical carbon dioxide into small volumes of collecting solvent. Finally, the extracts are injected into a capillary column gas chromatograph-ion-trap mass spectrometer without further concentration. In this paper, we present the recovery efficiencies, relative standard deviations, detection limits, and effects of an acetone solvent modifier on the SFE of reagent, tap, ground, and river water samples. Liquid-solid disk extraction coupled with supercritical fluid elution provides clear advantages in terms of sample preparation time, solvent use, and solvent disposal, especially for samples containing particulate matter.