Molecular-imprinted, polymer-coated quartz crystal microbalances for the detection of terpenes

A piezoelectric sensor coated with an artificial biomimetic recognition ele ment has been developed for the determination of L-menthol in the liquid ph ase. A highly specific noncovalently imprinted polymer (MIP) was cast in si tu on to the surface of a gold-coated quartz crystal microbalance (QCM) ele ctrode as a thin permeable film. Selective rebinding of the target analyte was observed as a frequency shift quantified by piezoelectric microgravimet ry with the QCM. The detectability of L-menthol was 200 ppb with a response range of 0-1.0 ppm. The response of the MIP-QCM to a range of monoterpenes was investigated with the sensor binding menthol in favor of analogous com pounds. The sensor was able to distinguish between the D- and L-enantiomers of menthol owing to the enantioselectivity of the imprinted sites. To our knowledge, this is the first report describing enantiomeric resolution with in an MIP utilizing a single monomer-functional moiety interaction. It is e nvisaged that this technique could be employed to determine the concentrati on of terpenes in the atmosphere.