FLUIDIZED-BED SOLID-PHASE EXTRACTION - A NOVEL-APPROACH TO TIME-INTEGRATED SAMPLING OF TRACE-METALS IN SURFACE-WATER

A new technique for solid-phase preconcentration of contaminants dissolved in surface waters is presented. The method is based on application of extraction material that is not packed, as in conventional solid-phase extraction systems, but instead is present in a freely floating form, as in a fluidized-bed reactor. The feasibility of the fluidized-bed extraction approach is demonstrated for the determination of heavy metals in surface waters using 8-hydroxyquinoline attached to solid supports as complexing agent. Recoveries, repeatability, and sensitivity appear satisfactory for this application, even when no filtration of the sample is done. As fluidized-bed extraction is based on free-floating, unpacked, extraction material, the pressure drop over the column is minimal and filtration is not required. Hence the technique seems eminently suited for deployment as an in situ, long-term, sampling method. As such it will provide time-integrated contamination levels that are not biased by biological variability or filtration artifacts, disadvantages of the commonly used methods for monitoring of contaminants in surface water.