CHIRAL DISCRIMINATION USING PIEZOELECTRIC AND OPTICAL GAS SENSORS

Odour perception in humans can sometimes discriminate different enanti omers of a chiral compound(1-3), such as limonene. Chiral discriminati on represents one of the greatest challenges in attempts to devise sel ective and sensitive gas sensors. The importance of such discriminatio n for pharmacology is clear, as the physiological effect of enantiomer s of drugs and other biologically active molecules may differ signific antly(4). Here we describe two different sensor systems that are capab le of recognizing different enantiomers and of qualitatively monitorin g the enantiomeric composition of amino-acid derivatives and lactates in the gas phase. One sensor detects changes in mass, owing to binding of the compound being analysed (the 'analyte'), by thickness shear-mo de resonance(5-7); the other detects changes in the thickness of a sur face layer by reflectometric interference spectroscopy(8-10). Both dev ices use the two enantiomers of a chiral polymeric receptor, and offer rapid on-line detection of chiral species with high selectivity.