Redox magnetohydrodynamic enhancement of stripping voltammetry: toward portable analysis using disposable electrodes, permanent magnets, and small volumes

Abstract

The use of redox magnetohydrodynamics (MHD) to enhance the anodic stripping voltammetry (ASV) response of heavy metals has been investigated, with respect to achieving portability: disposable electrodes consisting of screen-printed carbon (SPC) on a low temperature co-fired ceramic (LTCC) substrate, small volumes, and permanent magnets. The analytes tested (Cd(2+), Cu(2+), and Pb(2+)) were codeposited on SPC with Hg(2+) to form a Hg thin film electrode. High concentrations of Fe(3+) were used to produce a high cathodic current which generates a significant Lorentz force in the presence of a magnetic field. This Lorentz force induces solution convection during the deposition step, enhancing the mass transport of analytes to the electrode and increasing their preconcentrated quantity in the mercury thin film. Therefore, larger ASV peaks and improved sensitivities are obtained, compared to analyses performed without a magnet. The effects on ASV signal of varying Hg(2+) concentration (0.10 and 1.0 mM), deposition time (10-600 s), and electrode surface roughness were investigated. In addition, analyses were performed using a real lake water matrix. By using the disposable LTCC-SPC working electrodes in small volumes (150 microL) and with small permanent magnets (0.78 T), peak areas were increased by 75% when compared to the signal obtained in the absence of a magnetic field. A limit of detection of 25 nM for Cd(2+) was observed with only a 1 min preconcentration time.

Highly Sensitive Voltammetric Speciation and Determination of Inorganic Arsenic in Water and Alloy Samples Using Ammonium 2‐Amino‐1‐Cyclopentene‐1‐Dithiocarboxylate

“…In contrast, other reported voltammetric methods with mercury film electrodes require renewal of the working electrode after three to four runs, resulting in poor reproducibility. The MFE can be adapted to microfabricated electrodes for a miniaturized, chip-based format, such as depositing the mercury film at screen printed carbon electrodes on low temperature cofired ceramics [70]. Enhanced flux due to radial diffusion to MFE-carbon microelectrodes could then take the place of stirring at the [a] Arsenic found in the final sample solution after treatment with sodium sulfite.…”

Highly Sensitive Differential Pulse Voltammetric Determination of Cd, Zn and Pb Ions in Water Samples Using Stable Carbon‐Based Mercury Thin‐Film Electrode

“…Carbon electrodes were constructed as described in detail previously [25]. This involved first preparing and firing multi-layered LTCC substrates where screen-printed gold had coated the topmost layer.…”

“…Advantages of carbon electrodes, which make them useful for stripping voltammetry, include their high chemical and electrochemical stability, high hydrogen and oxygen overvoltages, broad potential window, and low cost [23][24][25]. To prepare the carbon electrode, carbon paste was applied by screen-printing on a low temperature co-fired ceramic (LTCC) substrate, which was plated with a mercury film.…”

Modified carbon-containing electrodes in stripping voltammetry of metals. Part II. Composite and microelectrodes

“…Table 3 gives examples of the use of modified thick-film electrodes for voltammetric determination of elements [145,. Metals and their oxides are the most common modifiers [145][146][147][148][149][150][151][152][153][154][155][156][157][158][159][160][161][162][163]. Sometimes the film electrodes are CC carbon composite, CCSG carbon-containing silica gel, DMG dimethylglyoxime, 9P3F 9-phenyl-3-fluorone, DMPT 4,7-dimethyl-1,10-phenanthroline, GCSG graphite-containing silica gel, DAN diaminonaphthalene, RNSH 5-(4-dimethyl amino benzelyden)-rhodamin, SGC sonogel-carbon, PMTP poly-3-methylthiophene, GEC graphite-epoxy composite, GCC graphite-containing composite, MBT 2-mercaptobenzothiazole, 8HQ 8-hydroxyquinoline, DPCO diphenyl carbazone, MWN multi-walled nanotubes, TCC thiacrown compound, bulk modifier introduced to electrode bulk preliminary, ex situ modifier fixed on surface preliminary, in situ formation of modifying layer during deposition of substance to be determined, NaAc sodium acetate, amm.buff.…”