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Hydrodynamic Modulation Voltammetry with a Dual Disk Chopped Flow‐Microjet Electrode (CF‐MJE)
Author(s) -
Simjee Nafeesa,
Unwin Patrick R.,
Macpherson Julie V.
Publication year - 2003
Publication title -
electroanalysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.574
H-Index - 128
eISSN - 1521-4109
pISSN - 1040-0397
DOI - 10.1002/elan.200302742
Subject(s) - electrode , chemistry , ultramicroelectrode , analytical chemistry (journal) , analyte , cyclic voltammetry , rotating disk electrode , volumetric flow rate , voltammetry , nozzle , signal (programming language) , phase (matter) , current (fluid) , modulation (music) , electrochemistry , mechanics , chromatography , acoustics , thermodynamics , physics , organic chemistry , computer science , programming language
A novel form of hydrodynamic modulation voltammetry (HMV) is described, based on the periodic variation of mass transport in a microjet electrode (MJE) system, in combination with phase‐sensitive detection techniques. In the configuration developed, a jet of solution is fired from a nozzle that is aligned directly over the surface of a dual disk Pt‐Pt ultramicroelectrode (UME). The potential at each electrode is controlled separately. A rotating blade, positioned between the nozzle and the UME probe, is used to periodically interrupt flow to the electrode surface, resulting in modulation of the overall mass transfer rate between two defined extremes. The use of a dual disk UME enables two transport‐limited current signals to be recorded simultaneously, one for the analyte of interest, and the other for a ‘reference species’ (oxygen for the studies described herein). The latter current response corresponds to the variation in mass transport rate in the chopped flow (CF) arrangement and is used as the signal for phase sensitive detection of the analyte current. Studies of potassium hexachloroiridate (III) [IrCl $\rm{ {_{6}^{3-}}}$ ] oxidation in aqueous solution are used to demonstrate the capabilities of the technique. HMV in the CF‐MJE arrangement allows quantitative concentration measurements, down to at least 5×10 −7 M.