Anodic detection in flow-through cells

Abstract

Virtually all organic compounds and numerous inorganic compounds are predicted from thermodynamics to be oxidized at potentials accessible at commonly used solid electrodes in aqueous media by reactions which require transfer of oxygen from H,O to the oxidation products. These anodic reactions are usually kinetically inhibited because of their complexity. Progress is summarized to develop electrocatalytic processes for anodic detection in flowing aqueous solutions.Pulsed amperometric detection at Pt electrodes is applicable for the sensitive detection of the HCOH group in all alcohols, polyalcohols and carbohydrates, the nitrogen in amines, amino acids and aminoglycosides, and sulphur in most inorganic and organic compounds. Pure and doped lead dioxide electrodes are described for amperometric detection at constant potential.The voltammetric response of electrocatalysed oxygen-transfer reactions is dictated by the potential dependence of the process transferring oxygen from H,O to the electrode surface, so that attempts at voltammetric resolution of mixtures are not generally effective. The most useful analytical application of the electrocatalysed processes for mixtures is in the form of amperometric detection in liquid-chromatographic systems.Electrochemical (EC) detection in miniature flow-through cells applied in conjunction with high-performance liquid-chromatographic (LC) separations joins together the analytical strengths of both component techniques. EC detection is highly sensitive at moderately low cost, whereas LC, in its numerous forms, is far superior to electroanalytical voltammetry in resolving power for analysis of complex mixtures. It is the goal of research summarized here to achieve maximum electrocatalytic activity for anodic EC detection, even at the sacrifice of voltammetric selectivity.

Development of Conducting Polymer Modified Electrodes for the Detection of Phenol

“…This problem becomes more severe as the concentration of phenol increases. Recently, the fouling process encountered during the oxidation of phenolic compounds has been investigated using electrochemical quartz crystal microbalance (EQCM) [4]. More broadly, electrode fouling is a common problem when solid electrode surfaces are used for electroanalysis [5].…”

Liquid Chromatography with Amperometric Detection at a Silver Based Detector for the Determination of Thiocompounds: Application to the Assay of Thiopurine Antimetabolites in Urine

“…The signal corresponds to the analyte oxidation and metallic oxide formation. [1][2][3] The selected PED waveform consists of alternated anodic and cathodic polarizations to clean the electrode through surface oxide formation and subsequent removal. This detection mode has been extensively investigated and is currently used in routine LC assays of sulfurcontaining compounds such as antibiotics and biothiols.…”

Glycosylation Analysis of a Recombinant P‐Selectin Antagonist by High‐pH Anion‐Exchange Chromatography with Pulsed Electrochemical Detection (HPAEC/PED)

“…These two factors limited the overall sensitivity of the method to ca. 10 nmol for each monosaccharide.Johnson and colleagues had developed a new type of electrochemical detector for the robust, sensitive, and reasonably selective detection of carbohydrates and other hydroxylated species by pulsed amperometry [2]. The triple-pulse voltage waveform they developed circumvented the problem of electrode fouling encountered when carbohydrates are analyzed by DC amperometry.…”