Performance of polymeric materials for solid phase extraction prior to chromatographic analysis

Synthetic polymeric materials such as polyethylene and polyurethane (PU) were compared to conventional adsorbents for solid phase extraction for cleaning up biological samples. Efficiency in eliminating proteins and other components usually present in biological samples, such as serum, urine, and tissues extracts, was evaluated. The assays consisted of measuring the remaining protein content in serum and tissue homogenates (liver) and collecting the spectra in the UV region for urine samples. Since the analysis of many endogenous and exogenous species in these matrices usually involves chromatographic separation, the efficiency of the clean-up procedures was also evaluated by injecting cleaned samples into a C-18 chromatographic column with UV detection. Among the investigated polymers, polytetrafluorethylene, high density polyethylene (HDPE) and ultra-high molecular weight polyethylene (UHMWPE) presented the best performance in retaining serum proteins. Proteic components of the liver homogenate were completely retained on polyurethane and polybutadiene (PB). Urine samples were cleaned by crossing columns of polytetrafluorethylene, ultra-high molecular weight polyethylene, high density polyethylene, polyurethane, and polyethylene co-butyl acrylate co-anhydride maleic (PEco), since the spectra collected after column percolation presented no peaks in the region between 190 and 390 nm. SPE cartridges showed different behavior, but along the lines of their usual performance; neither serum proteins nor urine components were retained on the phases and the liver components, though partially retained, were not desorbed with either water or methanol washes, with the exception of SAX. Chromatograms of samples cleaned with high density polyethylene showed that polymeric materials can be satisfactorily used as adsorbent for biological matrix components.