NANOBAND ELECTRODES FOR ELECTROCHEMICAL STRIPPING MEASUREMENTS DOWN TO THE ATTOMOLE RANGE

Small-volume measurements of lead and cadmium have been accomplished u sing a mercury-coated nanoband electrode. The band electrodes are fabr icated from ultrathin carbonized polyacrylonitrile films. The coupling of the inherent sensitivity of stripping analysis, with submicroliter sample volumes and enhanced plating efficiency (due to enhanced diffu sional flux) results in remarkably low detection limits of 100 femtogr ams (5 x 10(-16) mole) lead. To our knowledge, this detection limit is significantly lower than previously reported values for electrochemic al stripping work. Air-saturated quiescent sample droplets can thus be assayed by the square-wave or potentiometric stripping modes. Variabl es influencing the stripping response are explored and the stripping p erformance is characterized. Applicability to direct measurements of l ead microliter blood samples is illustrated.