Edge plane pyrolytic graphite electrodes in electroanalysis: an overview.

The recent development, behavior and scope of edge plane pyrolytic graphite electrodes in electroanalysis are overviewed. Similarities to, and advantages, over multi-walled CNT modified electrodes are noted and the wide scope of applications, ranging through gas sensing, stripping voltammetry and biosensing, illustrated

Ultrasound: promoting electroanalysis in difficult real world media.

This article outlines the recent progress in the field of sonoelectroanalysis with strong emphasis on 'real world media' analysis. General principles of stripping analysis and the effects of ultrasound are explained. A section on 'Electroanalysis in extreme media' presents several examples of applications including detection of copper in beer, manganese in tea, lead and cadmium in saliva. The benefits of diamond electrodes are described and in the final section 'Metal ion detection in blood' several novel approaches based on the use of power ultrasound and based on bismuth electrodes are discussed. Specifically it is shown that the combination of ultrasound with classical stripping voltammetry permits quantifiable measurements in media hitherto impossible to study using conventional methods

Ultrasonically enhanced voltammetric analysis and applications: An overview

Ultrasonically enhanced voltammetric measurements have been successfully applied for the detection of a wide range of trace metals. These are reviewed and the beneficial effects of power ultrasound applied to electroanalysis highlighted, most notably the possibility for quantitative analysis in otherwise highly passivating media, where classical electrochemical techniques often fail

Sonoelectroanalysis: A review

This review highlights recent advances made towards improving sonoelectroanalysis with an emphasis on applications where conventional electrochemical methodologies often fail. It is shown that: 1) the significantly increased mass transport regime under insonation very considerably enhances the sensitivity in comparison to what would be obtained under quiescent conditions and, in particular, 2) cavitational activity at the electrode solution interface provides depassivation in highly 'dirty' media or in the presence of undesirable surface active species and so can preserve quantitative electrode activity in complex, real world samples so removing the requirements for sample pretreatment which has hitherto limited the wider applications, for example, of stripping voltammetry

New electrodes for old: from carbon nanotubes to edge plane pyrolytic graphite.

Different types of carbon based electrodes have emerged over the last few years, significantly changing the scope and sensitivity of electro-analytical methods for the measurement of diverse targets from metal ions through gases to biological markers. This Highlight article shows how the use of carbon nanotube modified electrodes has led to a fundamental understanding of the location and nature of electron transfer processes on graphitic electrodes and to the realisation that edge plane pyrolytic graphite may represent, at present, an optimal electrode material of this type for electroanalysis

Exploring the electrocatalytic sites of carbon nanotubes for NADH detection: an edge plane pyrolytic graphite electrode study.

The electrocatalytic properties of multi-walled carbon nanotube modified electrodes toward the oxidation of NADH are critically evaluated. Carbon nanotube modified electrodes are examined and compared with boron-doped diamond and glassy carbon electrodes, and most importantly, edge plane and basal pyrolytic graphite electrodes. It is found that CNT modified electrodes are no more reactive than edge plane pyrolytic graphite electrodes with the comparison with edge plane and basal plane pyrolytic graphite electrodes allowing the electroactive sites for the electrochemical oxidation of NADH to be unambiguously determined as due to edge plane sites. Using these highly reactive edge plane sites, edge plane pyrolytic graphite electrodes are examined with cyclic voltammetry and amperometry for the electroanalytical determination of NADH. It is demonstrated that a detection limit of 5 microM is possible with cyclic voltammetry or 0.3 microM using amperometry suggesting that edge plane pyrolytic graphite electrodes can conveniently replace carbon nanotube modified glassy carbon electrodes for biosensing applications with the relative advantages of reactivity, cost and simplicity of preparation. We advocate the routine use of edge plane and basal plane pyrolytic graphite electrodes in studies utilising carbon nanotubes particularly if 'electrocatalytic' properties are claimed for the latter

Amperometric detection of glucose using self-catalytic carbon paste electrodes.

The analytical detection of d-glucose by means of self-catalytic carbon paste electrodes is described. In the construction of these electrodes, carbon powder has been modified with the redox liquid n-butylferrocene, which simultaneously serves both to help bind the paste together whilst also acting as a mediator in the enzymatic oxidation of d-glucose by glucose oxidase. The sensor then functions by monitoring the electrochemical oxidation of the constituent n-butylferrocene itself. Through testing in model glucose solutions, the electrodes were found to yield a linear response over a d-glucose concentration range of 2-20 mM. They were also successfully employed in the determination of d-glucose levels in a spiked blood sample, giving a detection limit of 0.8 mM (based on the 3sigma criterion)

Sonoelectroanalytical detection of ultra-trace arsenic

The electroanalytical detection of arsenic on a gold electrode is investigated in the presence and absence of ultrasound. It is found that under quiescent conditions a detection limit of 1.8×10-7 is achievable using a 120 seconds accumulation period. Applying optimised ultrasound during the accumulation period was found to reduce the limit of detection to 1 × 10-8 M from using a deposition period of 60 s at -0.5 V, while increasing the sensitivity by a factor of 15. The methodology was tested on a river sample containing significant copper contamination and electrode passivating organic materials. This technique provides promise for 'in the field' measurements due to the electrode-depassivating effects of ultrasound. © 2005 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim

Sonically assisted electroanalytical detection of ultratrace arsenic.

A simple portable handheld electrochemical sensor with an integrated sound source for the detection of ultratrace quantities of arsenic using square wave anodic stripping voltammetry is described. The sensor uses low-frequency sound (250 Hz) during the arsenic deposition step to enhance the sensitivity of the arsenic stripping response. It is found that under quiescent (silent) conditions a detection limit of 2.1 x 10(-7) M with a sensitivity of 0.51 M(-1) A is achievable using a 120-s accumulation period, while applying low-frequency sound using a "sonotrode" reduced this detection limit to 3.7 x 10(-9) M with an increased sensitivity of 27.2 M(-1) A. Thus, the low-frequency sonotrode is shown to increase the sensitivity by ca. 50 times while reducing the limit of detection by 2 orders of magnitude. A study of the effect of copper contamination is carried out as well as analysis in real samples; it is found that although as expected copper detrimentally effects the arsenic limit of detection, it does not rise significantly above 10(-8) M levels