APPLICATION OF CROWN-ETHER COATED PIEZOELECTRIC CRYSTAL AS A DETECTOR FOR ION CHROMATOGRAPHY

A reusable and sensitive piezoelectric guartz crystal detector was developed for the detection of either cations or anions in ion chromatography. The quartz crystal electrode coated with-crown ether (sym-dibenzo-16-crown-5-oxydodecanic acid) was prepared and was found to give the best results in terms of stability, sensitivity and reproducibility. Linear frequency (voltage) responses on a 10 MHz AT-cut crystal for ions were found on the range 0.1-5 x 10(-5) mol l(-1). Variations of the crystal frequencies were converted to voltage using a TC 9400 chip. Polystyrene-poly(divinyl benzene) with cryptand [2,2] as an anchoring group was synthesized and applied as a bifunctional ion chromatographic packing material for the separation of both cations and anions. The crown ether coated piezoelectric crystal detector with detection limits of 2 x 10(-5) (1 x 10(-10) mol)5 x 10(-5) mol l(-1) (2.5 x 10(-10) mol) for various ions showed a similar detection limit to that of a commercial conductivity detector in ion chromatography. The effects of solvents, reproducibility of responses and competitiveness with respect to a commercial conductivity detector were also investigated.