Selective detection of nitrogen and oxygen containing volatile organic compounds: use of metal-modified polysiloxanes as sensor coatings

Polysiloxanes containing 3-heptafluorobutanoyl (Hfb) camphorates of metal ions, e.g. zinc(II), nickel(II) and europium(III), have been used successfully as sensitive layers for thickness shear mode resonators (TSMRs). These sensing layers provide pronounced selectivity in detecting volatile organic compounds (VOCs) in the gas phase and in particular analytes containing heteroatoms, such as O and N. The selectivity results from co-ordinative binding between the electronically unsaturated metal complexes and the heteroatom-containing analytes. This leads to detection limits in the ng l−1 (ppb)-range especially for nitrogen-containing compounds under conditions of slow but perfect reversibility.