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

The authors describe a method for the extraction of 1-hydroxypyrene (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 mu m) 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.