Fullerene-crown ether coated piezoelectric crystal liquid chromatographic detector for metal ions and polar/nonpolar organic molecules

Fullerene(C60)-dibenzo-16-crown-5-oxyacetic acid (DB16C5-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 interface for signal acquisition and data processing was applied as an ion chromatographic (IC) detector for various metal ions, e.g., alkali metal, alkaline earth metal sind transition-metal ions. The piezoelectric detector exhibited 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 conventionally used for metal ions. The ionic size and ionic charge seemed to have significant effect on the frequency response of the piezoelectric detector. The C60-crown ether coated piezoelectric crystal sensor was also employed as a high performance liquid chromatographic (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 detector. 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 responses of the piezoelectric crystal detector were investigated. The C60-crown ether coated piezoelectric crystal detector also showed short response time (< 1 min.) and good reproducibility.