Silver Amalgam Electrode Research Articles

Highly Sensitive Determination of Tenofovir in Pharmaceutical Formulations and Patients Urine-Comparative Electroanalytical Studies Using Different Sensing Methods.

This paper discusses the electrochemical behavior of antiviral drug Tenofovir (TFV) and its possible applicability towards electroanalytical determination with diverse detection strategies using square-wave voltammetry. Namely, oxidation processes were investigated using glassy carbon electrode with graphene oxide surface modification (GO/GCE), while the reduction processes, related to the studied analyte, were analyzed at a renewable silver amalgam electrode (Hg(Ag)FE). Scanning electron microscopy imaging confirmed the successful deposition of GO at the electrode surface. Catalytic properties of graphene oxide were exposed while being compared with those of bare GCE. The resultant modification of GCE with GO enhanced the electroactive surface area by 50% in comparison to the bare one. At both electrodes, i.e., GO/GCE and Hg(Ag)FE, the TFV response was used to examine and optimize the influence of square-wave excitation parameters, i.e., square wave frequency, step potential and amplitude, and supporting electrolyte composition and its pH. Broad selectivity studies were performed with miscellaneous interfering agents influence, including ascorbic acid, selected saccharides and aminoacids, metal ions, non-opioid analgesic metamizole, non-steroidal anti-inflammatory drug omeprazole, and several drugs used along with TFV treatment. The linear concentration range for TFV determination at GO/GCE and Hg(Ag)FE was found to be 0.3–30.0 µmol L–1 and 0.5–7.0 µmol L–1, respectively. The lowest LOD was calculated for GO/GCE and was equal to 48.6 nmol L–1. The developed procedure was used to detect TFV in pharmaceutical formulations and patient urine samples and has referenced utilization in HPLC studies.

Electrodeposited silver amalgam particles on pyrolytic graphite in (spectro)electrochemical detection of 4-nitrophenol, DNA and green fluorescent protein

Catalytic properties and high adsorption affinity of nucleic acids and proteins to silver amalgam electrode surface make this kind of electrified interface perspective for bioanalytical and biomedical applications. For the first time, a basal-plane pyrolytic graphite electrode (bPGE) has been used as a substrate for electrodeposition of silver amalgam particles (AgAPs). Optimization of the resulting composition, surface morphology and electrochemical properties of the AgAPs was done by scanning electron microscopy with energy disperse X-ray spectroscopy, image processing software and voltammetric detection of electrochemically reducible model organic nitro compound, 4-nitrophenol. Spectro-electrochemical applicability of bPGE-AgAP has been demonstrated by electrolysis of 4-nitrophenol. Simultaneous UV–Vis-chronoamperometry provided information on the number of exchange electrons and the reduction rate constants. Preferential adsorption of the fluorescently labelled calf thymus DNA and the green fluorescent protein (GFP) on the surface of AgAPs was observed by fluorescence microscopy. In contrast to previously studied indium-tin oxide and vapour-deposited gold decorated by AgAPs, herein the presented bPGE-AgAP has provided sufficiently wide negative potential window allowing direct electroanalysis of non-labelled DNA and GFP using intrinsic electrochemical signals independently of the fluorescent labelling. The bPGE-AgAP can thus be expected to find application opportunities in protein electrochemistry, (bio)sensor development or in-situ spectro-electrochemical studies.

Influence of the lengths of thymine, cytosine, and adenine stretches on the two-dimensional condensation of oligodeoxynucleotides at mercury and silver amalgam electrode surfaces

Two-dimensional (2D) condensation of nucleic acid components at mercury electrodes around the potential of zero charge has been known for decades. In our previous pilot study, we reported on 2D condensation of homopyrimidine oligodeoxynucleotides (ODNs) at the hanging mercury drop electrode (HMDE) in negative potential region. In this work we focused in detail on the effect of the homopyrimidine ODN length (from 3- to 50-mers) on the formation and properties of 2D condensed films at the HMDE. To elicit possible orientation of the homopyrimidine ODN molecules in their 2D condensed layers (i.e. surface concentration of the ODN molecules and the cross-section areas per adsorbed ODN molecules) we used a model in which the maximum surface concentration of the adsorbed ODN molecules is determined from linear dependences of the square of capacitance pit width on temperature. Effect of the length of homoadenine ODNs on their adsorption/desorption processes were studied for comparison, as well as effects of ionic strength and base protonation. Further we focused on the effects of the length of periodically repeated homothymine/homocytosine stretches in 30-mer ODNs on their interfacial behavior at the negatively charged HMDE. Experiments with binary mixtures of non-complementary and complementary 15-mer homo-ODNs revealed dominance of the homopyrimidine, particularly cytosine, ODN responses in such competitive arrangement. The usefulness of solid silver amalgam electrode for this type of studies is demonstrated. Finally, potential applications of our results in label-free electrochemical analysis of alternative DNA structures are briefly discussed.

Electrochemical Analysis of Glycoprotein Samples Prepared on a Pneumatically‐controlled Microfluidic Device

AbstractIn this work, we designed and manufactured a microfluidic device for isolation and purification of glycoprotein samples. The conceived sample preparation device was fabricated in polycarbonate by micro‐milling. The flow control and the fluid dosage into the micro‐channels was solved by equipping the device with integrated pneumatic valves. The biochemical functionality was provided by beaded support modified by molecules with affinity to glycoproteins which was stacked inside the micro‐channel reminiscent of packed affinity columns used in glycoprotein lectin assays. Unlabeled glycoproteins, namely fetuin, asialofetuin, and prostate‐specific antigen, were voltammetrically analyzed using catalytic peak H at silver amalgam electrode.

Recent Applications of Silver Amalgam Electrodes for Analysis of Pharmaceuticals and Vitamins

The features and applications of silver amalgam electrodes in electroanalysis of pharmaceuticals and vitamins are summarized in this review. The state-of-the-art in the preparation and construction of solid silver amalgam electrodes for prolonged and userfriendly use is presented. Although not as widely spread as other electrode materials, silver amalgam possesses a unique and viable combination of favorable electrochemical properties, which are close to ideal mercury electrodes, non-toxic character, high durability and mechanical stability, if properly prepared. Its capability of conducting the redox processes at highly negative potentials is essential for the analysis of large number of bioactive organic compounds. The review features also overview information for each application in drug or vitamin analysis divided to the sections according to the construction variants of silver amalgam electrodes.

Voltammetric determination of aluminum(III) as Al-Alizarin S complex in tea leaves and infusions

This work presents, for the first time, DPV methodology of indirect aluminum (III) determination in tea leaves and infusions using the renewable silver amalgam electrode. A self-referencing strategy was proposed which relies on alternate voltammetric curves registration with and without conditioning of the electrode surface. The developed procedure utilizing formation of aluminum-Alizarin S complex shows linearity in the range of 2–50 μg L−1 of Al(III) concentration, with r > 0.997. In the case of the electrode conditioning LOD is 0.2 μgL−1 and repeatability expressed by CV is 1–2%. Introducing an additional operation i.e. electrode activation results in decrease of sensitivity from 0.0162 to 0.0043 μA/μgL−1. The method was verified using CRM (tea leaves). Due to the wide variety of tea origin, types and producers, four most popular sorts (black, green, red and white) were chosen, made by one manufacturer. It was demonstrated that the proposed methodology may be applied in Al(III) determination in tea leaves and infusions. Al(III) extraction effectiveness was also examined. It was verified, that lemon juice addition during brewing increases aluminum concentration in infusions. Using Principal Components Analysis it was demonstrated that automatic distinction of infusions brewed with and without lemon juice, based on unprocessed voltammetric signal, may be successfully realized.

Electrodeposition of silver amalgam particles on ITO – Towards novel electrode material

Silver solid amalgam represents up to now the most suitable alternative electrode material to metallic mercury in electroanalytical chemistry. Controlled electrodeposition of variable (sub)micrometer-sized silver amalgam particles (AgAP) on the surface of transparent indium-tin oxide (ITO) electrode from an electrolyte containing Ag+ and Hg2+ ions is reported here, as a novel perspective method suitable for preparation of nano-structured silver amalgam electrode material. Elemental analysis of the composition and morphology of the AgAP decorating the ITO was studied by scanning electron microscopy including energy-disperse X-ray spectroscopy and by image processing software. Particle composition, size, and surface coverage are controllable by selection of the Ag+/Hg2+ ratio in the electrodeposition solution and by setting of individual parameters of applied double pulsed/potential chronoamperometry. Applicable potential window of thus prepared ITO-AgAP electrode was found to be within +0.2 to −1.0V in 0.2acetate buffer pH5.0. Utilized voltammetric and chronoamperometric methods revealed significant enhancement in electrochemical reducibility of selected model organic nitro-compound (shift of the peak potential about 300mV to more positive potentials). Its further employment in UV/Vis spectroelectrochemical cell provided information about number of consumed electrons and kinetic characteristics. Furthermore preferential adsorption of calf thymus DNA at AgAP than ITO was observed by fluorescence microscopy indicating its potential applicability in (bio-)spectroelectrochemical methods. Further advantages and potential applications are also proposed and discussed.

Voltammetric Determination of Aclonifen at a Silver Amalgam Electrode in Drinking and River Water

Abstract A method for the determination of pesticide Aclonifen (AC) in drinking and river water by differential pulse voltammetry (DPV) on a meniscus modified silver solid amalgam electrode (m-AgSAE) using solid phase extraction (SPE) as a cleanup and preconcentration procedure is described. The limit of detection (LOD) for direct DPV determination of AC in deionized water is 2.7·10-8 mol·dm-3. LOD for DPV determination of AC in tap water after SPE is 1.6·10-10 mol·dm-3, the recovery being 55%. LOD for the determination of AC in Vltava river water is 1.9·10-9 mol·dm-3, the recovery being 65%. Humic acids interfere with the determination in river water; this problem can be resolved by adjusting the pH of the extracted sample to 6. The advantages of this approach are high sensitivity, low LOD, quick and easy sample preparation and fast determination.

Voltammetric determination of herbicide molinate in river water and rice samples using solid silver amalgam electrode fabricated with nanoparticles

ABSTRACTThe evaluation of the voltammetric behaviour and the determination of herbicide molinate were performed for the first time over the surface of solid amalgam electrode fabricated with silver nanoparticles using cyclic voltammetry and square-wave voltammetry techniques. The experimental and instrumental parameters were evaluated to reach the maximum analytical response for molinate. It was achieved when a medium composed of 0.04 mol L−1 Britton–Robinson buffer at the pH value of 4.0 was used. Under these conditions, molinate showed one pronounced reduction peak at Ep = −0.37 V (vs. Ag/AgCl 3 mol L−1) that was characterised as an irreversible system. An analytical curve was constructed at the concentration range from 9.36 to 243.49 µg L−1 and a limit of detection of 2.34 µg L−1 was obtained. The amalgam electrode presented good stability during the measurements with relative standard deviation (RSD) values of 2.9% for the repeatability and 5.4% for the reproducibility. The voltammetric method developed here could be conveniently applied for the determination of molinate in river water and rice spiked samples at levels below those established on the legislations of European Union and Brazil with good accuracy (RSD of less than 5% for all samples). Comparison with HPLC technique was carried out and the results indicated satisfactory concordance. According to the results depicted here, the silver nanoparticles solid amalgam electrode showed itself highly sensitive and an interesting alternative for the routine analysis of molinate in water and food samples. Furthermore, it introduces an environmentally acceptable alternative to the mercury electrodes, most commonly used for determination of reducible pesticides.

Voltammetric determination of aluminum-Alizarin S complex by renewable silver amalgam electrode in river and waste waters

The direct voltammetric determination of aluminum is difficult because it is reduced at very low potential −1.75V versus Ag/AgCl. Therefore, in this work a simple and rapid stripping voltammetry method of Alizarin S-Al complex determination on renewable silver amalgam film electrode was proposed. The electrode process in complex electrolyte is irreversible and controlled by the surface phenomena. Experimental conditions such as preconcentration time and operation parameters were optimized. The promising results were obtained in 0.1M ammonia buffer, 0.01M KBrO3, 0.25μM Ca, 0.1μM EDTA. The calibration graph was linear from 5 to 45μgL−1 with sensitivity of 14.6μA/mgL−1, detection limit of 0.2μgL−1 and repeatability below 3.5%. With accumulation time of 4s the sensitivity increases to 17.4μA/mgL−1 with r=0.9978 but the range of linearity was limited to 20μgL−1. The problem of the main interferent which is zinc was resolved by the EDTA addition. Procedure was verified using waste waters CRMs with recovery 99–110% and spiked Vistula River water.

Mercury meniscus on solid silver amalgam electrode as a sensitive electrochemical sensor for tetrachlorvinphos

The in-house prepared mercury meniscus modified solid silver amalgam electrode (m-AgSAE) was successfully applied for the detection of organophosphate pesticide tetrachlorvinphos in pH 7 buffer solution. The electrochemical performance of m-AgSAE for the reduction of tetrachlorvinphos was evaluated using cyclic voltammetry (CV), differential pulse voltammetry (DPV), and square wave voltammetry (SWV), respectively. The surface morphology of solid silver electrode (AgE), as-amalgamated solid silver amalgam electrode (AgSAE), and polished solid silver amalgam electrode (p-AgSAE) was examined by field emission scanning electron microscopy (FESEM). Among the applied techniques, DPV and SWV analysis showed a remarkable increase in the reduction peak current and provided a simple, fast, and sensitive method for the determination of tetrachlorvinphos. The electrochemical impedance spectroscopy (EIS) was used to correlate the electrocatalytic activity of AgSAE, p-AgSAE and m-AgSAE with their interfacial charge transport capabilities. Under the optimized experimental conditions, the DPV and SWV responses were linear over the 1–9μM and 10–50μM concentration ranges with a detection limit of 0.06μM for DPV and 0.04 for SWV. The estimation of tetrachlorvinphos in the ground and waste water samples with the proposed method was in good agreement with that of the added amount. The proposed electrochemical method not only extends the application of non-toxic m-AgSAE, but also offers new possibilities for fast and sensitive analysis of tetrachlorvinphos and its structural analogs in environmental samples.

Conformational change of bovine serum albumin molecules at neutral pH in ultra-diluted aqueous solutions.

Surface chemical and electrochemical techniques were applied to reveal the unfolding of bovine serum albumin (BSA) molecules induced by concentrations in aqueous solution. Real-time surface pressures vs time (π-t) kinetic curves were recorded over an aqueous subphase (190 mL) by spreading BSA solutions of different concentrations but of the same amount (8.0 × 10(-4) mg) at the air/water (A/W) interface. A critical concentration (∼1.0 ppm) was discovered below which the surface pressure declines with time and the BSA is totally solubilized in the water subphase. Above this critical concentration (e.g., 8.0 ppm), the surface pressure goes up and the protein molecules assemble into a Langmuir monolayer at the A/W interface. These findings demonstrate that the BSA molecules have different conformations in the spreading protein solutions. The conformational transition in BSA molecules induced by concentrations was also confirmed by spectroscopy means and the catalytic hydrogen evolution reaction on a silver amalgam electrode by using constant current chronopotentiometric stripping. This discovery fills in gaps of Foster's N (normal) → F (fast) model, in which the unfolding of BSA molecules occurs at neutral pH values (8.0-4.3).

Thiolate monolayers formed on different amalgam electrodes. Part II: Properties and application

Properties of thiol monolayers were investigated at electrodes of solid amalgams of silver, copper, bismuth, cadmium (MeSAE) and at hanging mercury drop electrode (HMDE). The concentration dependences of studied thiol (HS(CH2)10COOH; MUA) at HMDE, m-AgASE, MF-AgSAE and m-CuSAE were similar for all electrodes and the Langmuir equation was used for evaluation of obtained results. Calculated values of ΔGads were very close for all electrodes. The lowest saturated surface coverage was observed for HMDE (8.5×10−10molcm−2) and the highest one for MF-AgSAE (9.8×10−10molcm−2). Nonlinear dependences of the peak currents on the scan rate show that lateral interactions exist among adsorbed molecules. When the scan rate is increased, the negative value of the peak potential increases proportionally with the natural logarithm of the scan rate. The potential of the desorption peak is almost unchanged if the thiol surface coverage (Θ) is 50% or lower. At higher values of Θ the adsorbate molecules attract each other and the peak potential at all electrodes shifts to more negative values. The dependence of the peak width at half height (W1/2) on Θ shows that the desorption peak is wide if the surface coverage is approximately 50% or lower. From Θ≈80% up to full coverage of the electrode surfaces the peak width practically does not change and W1/2≈9–12mV. Statistical results of repeated preparations of thiol monolayer and its subsequent desorption confirm that stationary amalgam electrodes are a suitable instrument to study the electrochemical properties of thiol films. Biosensor based on the use of strong and selective (strept)avidin–biotin interaction has been prepared for the first time at silver amalgam electrodes. Avidin or streptavidin are bound to the MUA monolayer by amide bond and therefore such biosensor is very stable.

Determination of chromium in estuarine waters by catalytic cathodic stripping voltammetry using a vibrating silver amalgam microwire electrode

Chromium (CrVI) in water can be determined by adsorptive catalytic cathodic stripping voltammetry in the presence of diethylenetriaminepentaacetic acid (DTPA) and nitrate on the hanging mercury drop electrode (HMDE). Predominately CrVI is detected and the water is UV-digested to convert all Cr to CrVI prior to analysis. We develop here an alternative to the HMDE by using a silver amalgam electrode based on a vibrating microwire. The microwire electrodes were 12.5μm in diameter and electrochemically coated with mercury, and were stable for a week. Conditions were re-optimised, and we used a DTPA concentration of 5mM, 30mM acetate pH buffer (pH 5.5 in seawater and pH 5.8 in pure water), and 1.5M nitrate solution. The microwire was reactivated prior to each scan by applying a negative potential (−3V) for 2s which removed all deposited Cr. The detection limit for chromium in pH buffer was found to be 0.2nM CrVI and in seawater 0.3nM CrVI at a deposition time of 30s. The response increased linearly with the concentration of CrVI up to 60nM CrVI in seawater. The limit of detection is less good than using the HMDE, but the linear range is good and the microwire electrode could form the basis of apparatus for flow-analysis. The method was successfully tested on water samples from the estuary of the river Mersey (Liverpool Bay) giving chromium concentrations between 1.48nM and 2.29nM.

Voltammetric and amperometric determination of selected dinitronaphthalenes using single crystal silver amalgam based sensors

Modern voltammetric techniques, combined with the quasi-cylindrical single crystal silver amalgam electrode (CAgAE) tested, were used for determination of selected environmental pollutants, 1,3-dinitronaphthalene, 1,5-dinitronaphthalene and 1,8-dinitronaphthalene. The optimum conditions were found for the determination of selected dinitronaphthalenes (DNNs) using direct current voltammetry and differential pulse voltammetry. The procedures were applied to determination of these analytes in model samples of tap water. The 1,3-, 1,5- and 1,8-DNN were determined by differential pulse voltammetry (DPV) with limits of quantification 1.0, 1.0 and 0.3μmoll−1 in concentration range up to 100μmoll−1 in Britton–Robinson buffer and methanol mixture (1:1) with final pH 8.2, 12.3 and 8.2, respectively. The 1,3-, 1,5- and 1,8-DNN were then determined by DPV with limits of quantification 0.4, 0.5 and 0.4μmoll−1 in model samples of tap water conditioned by Britton–Robinson buffer (9:1) pH 7.0, 12.0 and 7.0, respectively, in presence of 0.001moll−1 Na2EDTA. Adsorptive stripping differential pulse voltammetry was unsuccessfully tested in an attempt to obtain lower limits of quantification. The processes occurring during the DNNs reduction at the CAgAE were also investigated by cyclic voltammetry. A single crystal of the silver amalgam was then used to design a cylindrical flow-through detector which was utilized for amperometric detection of selected DNNs in a mixture, after their separation by conventional HPLC. The optimum separation and detection conditions for the DNNs at the cylindrical flow-through detector were found. The DNNs were separated using column with reverse phase C-18, ammonium acetate pH 4.7–methanol (27:73) as mobile phase at flow rate 1.5mlmin−1 and detected by the cylindrical detector at potential −1.2V with limit of detection 1μmoll−1 within concentration range up to 100μmoll−1. Single-crystal silver amalgam was found to be a suitable alternative for “toxic” mercury in voltammetric measurements and a convenient electrode material for designing a new amperometric detector.

Properties of thiolate monolayers formed on different amalgam electrodes

Formation and properties of thiol (HS(CH2)10COOH or HS(CH2)10CH3) monolayers were investigated at stationary electrodes based on silver, copper, bismuth and cadmium solid amalgams covered by a mercury meniscus or by a mercury film (m-AgSAE, MF-AgSAE, m-CuSAE, m-BiAgSAE and m-CdSAE). For comparison, parallel experiments were performed at a classical hanging mercury drop electrode (HMDE). Thiol monolayers were prepared at an optimal deposition potential (e.g., for HS(CH2)10COOH Eac=−350mV for HMDE and silver amalgam electrodes, Eac=−750 to −800mV for m-CuSAE and m-BiAgSAE, and Eac=−1050mV for m-CdSAE) at which the formed layers exhibit high density and stability. It was found that the potential of a reductive desorption peak of a thiol monolayer strongly depends on the metal which forms the amalgam (for HS(CH2)10COOH: Ep=−864 to −859mV for HMDE and silver amalgam electrodes, Em-BiAgSAE=−1079mV, Em-CuSAE=−1136mV and Em-CdSAE=−1248mV). This allows to create a stable thiol layer in different potential regions according to its application. The influence of a thiol layer charge on the reduction potential was determined.

Crystallic silver amalgam – a novel electrode material

A crystallic silver amalgam was found to be a suitable working electrode material for voltammetric determination of electrochemically reducible organic nitro-compounds. Optimum conditions for crystal growth were found, the crystal surface was investigated by atomic force microscopy in tapping mode and single crystals were used for the preparation of quasi-cylindrical single crystal silver amalgam electrode (CAgAE). An electrochemical behavior of this alternative electrode material was investigated in aqueous media by direct current voltammetry, cyclic voltammetry (CV), differential pulse voltammetry (DPV) and adsorptive stripping voltammetry (AdSV) using 4-nitrophenol as a model compound. Applicable potential windows of the CAgAE were found comparable with those obtained at a hanging mercury drop electrode, providing high hydrogen overpotential, and polished silver solid amalgam electrode. Thanks to the smooth single crystal electrode surface, the effect of the passivation is not too pronounced, direct DPV determination of 100 μmol l(-1) of 4-nitrophenol at CAgAEs in 0.2 mol l(-1) acetate buffer pH 4.8 provides a RSD around 1.5% (n = 15). DPV calibration curves of 4-nitrophenol are linear in the whole concentration range 1-100 μmol l(-1) with a limit of quantification of 1.5 μmol l(-1). The attempt to increase sensitivity by application of AdSV was not successful. The mechanism of 4-nitrophenol reduction at CAgAE was investigated by CV.

The effect of composition of solid silver amalgam electrodes on their electrochemical response

The main purpose of this work was to evaluate the effect of the silver to mercury ratio on the voltammetric responses of silver solid amalgam electrodes (AgSAE’s). For this, the AgSAE were prepared by mechanical mixing the metals in the following mass ratios of silver to mercury: 30/70, 40/60, 50/50, 60/40, and 70/30. The resulting AgSAE’s were physically characterized by energy dispersive X-ray analysis, X-ray diffraction and scanning electron microscopy, confirming the mass percentages of the silver and mercury, the total absence of liquid mercury and a globular structure of all AgSAE’s. Furthermore, it was observed that the AgSAE 30/70 contained only one single phase (Ag2Hg3), and no metallic silver or mercury oxides. Additionally, the resulting AgSAE’s were chemically characterized with respect to the influence of the electrode composition on the reproducibility and electrochemical signals of a hexamine-ruthenium (III) chloride solution by use of electrochemical impedance spectroscopy and cyclic voltammetry. The separation between anodic and cathodic peaks, and consequently, the charge transfer resistance across the electrode/solution interface, and the electroactive area were calculated demonstrating that the 30/70 composition is the best surface for practical applications. Finally, square-wave voltammetry experiments were performed in 4-nitrophenol solution, with a previous optimization of the experimental and voltammetric parameters. The calculated detection limit shows that the AgSAE 30/70 is suitable for determining any contamination by p-nitrophenol, minimizing the toxic residues in case of using liquid mercury electrodes.

Nafion Coated Silver Amalgam Electrode for Determination of Trace Metals by Anodic Stripping Voltammetry

AbstractThis paper describes characterization and application of Nafion coated solid silver amalgam electrodes to prevent surface fouling of surfactants in determination of trace metals by differential pulse anodic stripping voltammetry (DPASV). Polymer films of different thickness were tested using Nafion solutions in the range 0.25%–1%. Optimum thickness was archived using a 0.5% Nafion solution, resulting in both increased response and stability over time compared to uncoated electrodes. The influence of model surface active macromolecules was studied using triton X‐100, sodium dodecyl sulfate, dodecyl pyridinium chloride and bovine serum albumin as representatives for surfactants. The resistance to surfactants makes the studied Nafion coated solid silver amalgam electrodes an interesting alternative for practical use in environmental monitoring.

Determination of Manganese in Natural Media by Anodic Stripping Voltammetry Using a Rotating Solid Silver Amalgam Electrode

AbstractDetection of Mn(II) using differential pulse anodic stripping voltammetry (DPASV) on solid silver amalgam electrode is introduced. A well‐defined peak for the oxidation of Mn(0) to Mn(II) was observed around −1.45 V in NH4Cl (0.05 M) solution. Concentrations down to 1 μg/L were measured in NH4Cl (0.05 M) with 900 s deposition time at −1.70 V, and good linearity was observed (r=0.993) for standard additions in different concentration ranges (1–3 μg/L, 10 μg/L–60 μg/L, and 50 μg/L–250 μg/L). For all measurements relative standard deviation was within 5% (n=9). Interactions between Mn and Cd, Ni, Cu, Pb and Zn were examined, and it was found that lead and nickel significantly interfere, while zinc, cadmium, copper, and mercury did not interfere within reasonable concentration ranges. The method was demonstrated for online detection of manganese in a contaminated river where the Mn(II) concentration varied between 3 and 15 μg/L. The relation between the Mn(II) concentration in the river water and the vessel traffic was observed due to the presence of high concentrations of Mn(II) in anoxic pore waters.