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We report the electroanalytical determination of lead by anodic stripping voltammetry at in-situ-formed, bismuth-film-modified, boron-doped diamond electrodes. Detection limits in 0.1 mol L(-1) nitric acid solution of 9.6 x 10(-8) mol L(-1) (0.2 ppb) and 1.1 x 10(-8) mol L(-1) (2.3 ppb) were obtained after 60 and 300 s deposition times, respectively. An acoustically assisted deposition procedure was also investigated and found to result in improved limits of detection of 2.6 x 10(-8) mol L(-1) (5.4 ppb) and 8.5 x 10(-10) mol L(-1) (0.18 ppb) for 60 and 300 s accumulation times, respectively. Furthermore, the sensitivity obtained under quiescent and insonated conditions increased from 5.5 (quiescent) to 76.7 A mol(-1) L (insonated) for 60 s accumulation and from 25.8 (quiescent) to 317.6 A mol(-1) L (insonated) for 300 s accumulation. Investigation of the use of ultrasound with diluted blood revealed detection limits of the order of 10(-8) mol L(-1) were achievable with excellent inter- and intra-reproducibility and sensitivity of 411.9 A mol(-1) L. For the first time, electroanalytical detection of lead in diluted blood is shown to be possible by use of insonated in-situ-formed bismuth-film-modified boron-doped diamond electrodes. This method is a rapid, sensitive, and non-toxic means of clinical sensing of lead in whole human blood.

Bismuth-modified glassy carbon electrodes have been investigated for their suitability in sonoelectroanalysis. The stability of the bismuth film to the application of ultrasound was assessed via voltammetric and atomic force microscopy (AFM) studies which revealed little ablation at powers up to an intensity of 130 W cm(-2) delivered from a 25-kHz sonic horn. Furthermore, bismuth-film-modified glassy carbon electrodes were evaluated for the sonoelectroanalytical quantification of zinc and cadmium. Detection limits of 2 x 10(-7) M and 6 x 10(-9) M respectively were found after a 60-s deposition time via an acoustically assisted deposition protocol.

Electrochemical processes at negatively polarized electrical double layer capacitor (EDLC) electrode at different cell potentials have been studied using in situ synchrotron radiation excited X-ray photoelectron spectroscopy (XPS). 1-Ethyl-3-methylimidazolium tetrafluoroborate (EMImBF4) room-temperature ionic liquid (RTIL), as an electrolyte, and Mo2C derived carbon (C(Mo2C)) based micromesoporous electrodes, as an EDLC electrodes, were studied within very wide cell potential region (up to 4.0 V). To store more charge in a RTIL based EDLC, higher cell potentials have been applied leading to the cross-over of the limit of the ideal polarization of the capacitor electrodes and to the initiation of different faradaic processes. Therefore, parallel to XPS measurements, the cyclic voltammetry was used to obtain electrochemical data, correlated with previously calculated electrochemical (including electrochemical impedance spectroscopic) characteristics for C(Mo2C) | RTIL interface. In this paper we have, according to our knowledge, first polarized the RTIL based EDLC electrodes in real in situ vacuum conditions, measured and analyzed the supercapacitor two-electrode cell potential vs. XPS spectra relationship and discussed in the light of XPS data possible electrochemical reactions taking place at the negatively charged working electrode | RTIL interface at the different cell potential applied.

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