Membrane approach to solid-phase extractions

A novel material for separations has been developed in which efficient chromatographic particles are enmeshed in a network of PTFE fibrils to form a strong, porous sheet or “membrane”. The membrane can have a variety of sorptive or reactive properties, which are determined by the characteristics of the particulate chosen. The membranes, in the form of 47- or 25-mm disks, are used with standard filtration equipment. The use of hydrophobic octyl- and octadecyl-bonded silica particulates for reversed-phase extractions of environmental pollutants from an aqueous matrix, replacing conventional liquid-liquid extraction (LLE) is described. The water sample is filtered through the disk and adsorbed organic species are eluted from the disk with a small volume of an appropriate solvent for subsequent chromatographic separation. The technique is rapid, less labor intensive then LLE and eliminates the need for large volumes of hazardous and expensive solvents. Specific applications investigated include the analysis of ground, surface and tap waters for pesticides, polychlorinated biphenyls and phthalates at the μg l^?1 level.