Molecularly imprinted titania microbeads for extraction of the metabolite 1-hydroxy pyrene from urine prior to its determination by HPLC

The authors describe a method for the extraction of 1-hydroxy pyrene (1-OHP) from urine by using a molecularly imprinted TiO₂ gel, and the determination of 1-OHP by HPLC. This method was applied to determine levels of 1-OHP in urine of patients in order to estimate the degree of exposure to polycyclic aromatic hydrocarbons. The molecularly imprinted TiO₂ gel (MITiG) was prepared by polycondensation of titanium(IV) butoxide in the presence of the template 1-OHP. The gel was deposited in the form of a thin film on a quartz support, and the 1-OHP template was eluted. The resulting MITiG binds 1-OHP much better than chemically related species. The MITiG was then applied to prepare micro beads (with a typical diameter of 500–600 μm) to enlarge the specific surface. These beads were used to extract 1-OHP from urine. Following elution of 1-OHP with ethanol, it was quantified by HPLC with fluorescence detection at excitation/emission wavelengths of 242/388 nm. The method is accurate, cheaper and faster than the often used enzyme-based method. (author)