Fullerene‐Crown Ether Coated Piezoelectric Crystal Liquid Chromatographic Detector for Metal Ions and Polar/Nonpolar Organic Molecules

Abstract

Fullerene(C60)-dibenzo-16-crown-5-oxyacetic acid (DBI6C5-OCH2-COOC60) was prepared and applied as the coating material on piezoelectric quartz crystals for detection of various metal ions and polar/nonpolar organic molecules. The C60-crown ether-coated piezoelectric crystal sensor with a home-made computer inter face for signal acquisition and data processing was applied as an ion Chromatographie (IC) detector for various metal ions, e.g., alkali metal, alkaline earth metal and transition-metal ions. The piezoelectric detector exhib ited quite good sensitivity of 10 4 ~ 10 6 Hz/M and good detection limit of 10" 3 ~ 10" 4 M for these metal ions. The C60-crown ether piezoelectric detector compared well with the commercial conductivity detector convention ally used for metal ions. The ionic size and ionic charge seemed to have significant effect on the frequency re sponse of the piezoelectric detector. The C60-crown ether coated piezoelectric crystal sensor was also em ployed as a high performance liquid Chromatographie (HPLC) detector for various polar organic molecules with frequency responses in the order: amines > carboxylic acids > alcohols > ketones. Furthermore, nonpolar organic molecules, e.g., n-hexane, 1-hexene and 1-hexyne, were also detected with this piezoelectric crystal de tector. The frequency responses of the piezoelectric crystal detector for these nonpolar organic molecules were in the following order: alkynes » alkenes > alkanes. The effects of solvents and flow rate on the frequency re sponses of the piezoelectric crystal detector were investigated. The C60-crown ether coated piezoelectric crys tal detector also showed short response time (< 1 min.) and good reproducibility.