Chiral discrimination by simple gas sensors

The discrimination of optical isomers (enantiomers) in the gas phase has been performed using thickness shear mode resonators (TSMRs). The selective coatings included both enantiomers ((S)- and (R)-receptor) of a Chirasil-Val(R)-derivative (stationary phase material in gas chromatography (GC)) with octyl-side chains. A successful discrimination of the enantiomers of different types of analytes (amino acids and lactates) was achieved. The results were in good agreement with GC-measurements. In addition different mixtures of the enantiomers of the respective analyte were investigated and the enantiomeric composition could be determined quantitatively with excellent reliability. Thus, the sensors allow an on-line-monitoring (not possible for GC) of enantiomeric purity.