Electrocatalytic response of cobalt phthalocyanine chemically modified electrodes toward oxalic acid and .alpha.-keto acids

Santos, Leonel M.; Baldwin, Richard P.

doi:10.1021/ac00295a045

Cited by 96 publications

(26 citation statements)

References 34 publications

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“…The cyclic voltammogram of the accumulated oxalate at the modified CPE is characterized by the following facts: (i) a single anodic peak with a peak potential around 1.2 V; no corresponding reduction peak was observed on the reverse scan under the conditions employed; (ii) the peak potential is nearly independent of the pH of the electrolyte, whereas, the peak current varies with the pH change (see below); (iii) a slight concentration dependence: small shift in peak potential in the cathodic direction upon increasing the oxalate concentration. The described voltammetric behavior is very similar to that reported by using a plain CPE [24] or a glassy carbon electrode [26,27[, when oxalic acid was added directly into the supporting electrolyte. In order to further optimize the voltammetric measurement, SWV, instead of linear sweep voltammetry, was introduced due to its improved peak shape and higher sensitivity.…”

Section: Accumulation and Voltammetric Behavior Of Oxalic Acid At Thesupporting

confidence: 78%

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Insoluble inorganic salts as carbon paste electrode modifiers for preconcentration and voltammetric determination of oxalic acid

et al. 1995

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A novel approach for chemical modification of carbon paste electrodes (CPEs) has been investigated. Selected water-insoluble inorganic salts as modifiers were found to exhibit preconcentration capability for oxalic acid under open-circuit conditions in a pH 4.3 buffered solution. After medium exchange to a pure electrolyte (Britton-Robinson buffer, pH 8), the accumulated oxalate was measured by squarewave anodic stripping voltammetry with a peak current response at 1.2 V (vs. Ag/AgCl). The water-insoluble inorganic salts as modifiers were active through the interfacial accumulation of insoluble oxalate by the exchange of anions. The candidate inorganic salts should be, therefore, less insoluble than the corresponding oxalates, whereas, the differences in solubility between the modifiers and the corresponding oxalates are of minor importance. Among the investigated inorganic salts, lead sulfate produced the highest response under the employed conditions and was therefore exploited as accumulating material for oxalic acid. With suitable preconcentration times, a linear calibration graph from 0.7 mg/L to 42.8 mg/L of oxalic acid in the analyte solution was obtained, and a detection limit of 0.3 mg/L at a preconcentration time of 5min was achieved. The lead sulfate-modified CPE was used to determine oxalic acid in orange juice without pre-separation.

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Section: Accumulation and Voltammetric Behavior Of Oxalic Acid At Thesupporting

confidence: 78%

“…This new type of modification was proved by the development of a simple method for open-circuit preconcentration and subsequent voltammetric determination of oxalic acid with lead sulfate as the best modifier among the examined inorganic salts, due to its highest accumulation ability for oxalic acid. mol/L [24].…”

Section: Introductionmentioning

confidence: 97%

Insoluble inorganic salts as carbon paste electrode modifiers for preconcentration and voltammetric determination of oxalic acid

et al. 1995

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“…Electrooxidation of oxalic acid on metal-phthalocyanine chemically modi®ed carbon paste electrode surface [11] or on a solgel-derived carbon composite electrode [12] has been reported. Wang et al [12] have observed that dispersion of the electroactive species on the electrode surface resulted in a great improvement of stability and electrocatalytic action.…”

Section: Introductionmentioning

confidence: 99%

Cobalt(II) Tetrasulfophthalocyanine Complex Adsorbed on a Silica Gel Surface Chemically Modified with 3-N-Propylpyridinium Chloride: Oxalic Acid Oxidation Study

Ribeiro

Gushikem²

1999

Electroanalysis

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Cobalt(II) tetrasulfophthalocyanine complex was adsorbed on the 3-N-propylpyridinium chloride functionalized silica gel surface by means of an ion exchange reaction. The speci®c surface area of the modi®ed silica was S BET 320 m 2 g À1 and the amount of the complex bonded to the substrate surface was 17 mmol g À1. A carbon paste electrode made with electrocatalytically oxidized oxalic acid at an anodic potential E pa 850 mV in 0.5 M KCl solution at pH 2. The anodic peak current intensities were linearly correlated with oxalic acid concentrations between 3.97 and 19X2 Â 10 À3 M. The electrode showed a very reproducible response and was chemically very stable under various oxidation-reduction cycles. The electrode was applied in the determination of oxalic acid in a spinach sample.

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“…Oxalate oxidation peaks at BPPG and EPPG electrodes appeared at lower potentials, þ 1.13 and 1.20 V vs. SCE respectively, and with peak currents higher than one obtained at GC electrode. Carbon electrode reactivity in general is, depending on the analyte, influenced by surface cleanliness [32], surface microstructure [33], hydrophobicity/hydrophilicity [13], electronic structure, i.e., density states [34] and surface carbon oxides [35]. …”

Section: Resultsmentioning

confidence: 99%

Electrochemical Determination of Oxalate at Pyrolytic Graphite Electrodes

2007

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The electrocatalytic oxidation of oxalate at several carbon based electrodes including basal plane (BPPG) and edge plane (EPPG) pyrolytic graphite and glassy carbon (GC) electrode, was studied. The electrodes were examined for the sensing of oxalate ions in aqueous solutions and all three electrodes showed a response to oxalate additions. The peak of oxalate oxidation at BPPG electrode appeared at lower potential, þ 1.13 V vs. SCE, than at EPPG (þ 1.20 V vs. SCE) and GC electrode (þ 1.44 V vs. SCE). Oxalate oxidation at BPPG electrode was studied in more details for response characteristics (potential and current), effects of pH, temporal characteristics of response potential and current. The results indicated that oxalate oxidation proceeds as two-electron process at the BPPG electrode with a transfer coefficient b and a diffusion coefficient D evaluated to be 0.45 and 1.03 (AE 0.04) Â 10 À5 cm 2 s À1 respectively. The BPPG electrode was found to be suitable for oxalate determination in aqueous media showing linear response to oxalate concentration with a sensitivity of 0.039 AM À1 and a limit of detection of 0.7 mM.

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Electrocatalytic response of cobalt phthalocyanine chemically modified electrodes toward oxalic acid and .alpha.-keto acids

Cited by 96 publications

References 34 publications

Insoluble inorganic salts as carbon paste electrode modifiers for preconcentration and voltammetric determination of oxalic acid

Insoluble inorganic salts as carbon paste electrode modifiers for preconcentration and voltammetric determination of oxalic acid

Cobalt(II) Tetrasulfophthalocyanine Complex Adsorbed on a Silica Gel Surface Chemically Modified with 3-N-Propylpyridinium Chloride: Oxalic Acid Oxidation Study

Electrochemical Determination of Oxalate at Pyrolytic Graphite Electrodes

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