Application of the Potentiometric Stripping Analysis with Constant Current for the Determination of Lithium Ions Using a Spinel-Type Manganese (IV) Oxide-Modified Carbon Paste Electrode

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Study of the potentiometric response of the doped spinel Li1.05Al0.02Mn1.98O4 for the optimization of a selective lithium ion sensor

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Development of a sensitive potentiometric sensor for determination of fumaric acid in powdered food products

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Potentiometric determination of captopril in pharmaceutical formulations

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Potentiometric Sensor for Furosemide Determination in Pharmaceuticals, Urine, Blood Serum and Bovine Milk

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Potentiometric sensor for sorbic acid determination in food products

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Development of a potentiometric sensor for the determination of saccharin in instant tea powders, diet soft drinks and strawberry dietetic jam

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Development of a potentiometric flufenamate ISE and its application to pharmaceutical and clinical analyses

The characteristics, performance, and application of an electrode, namely, Pt vertical bar Hg vertical bar Hg-2(FF)(2)vertical bar Graphite, where FF stands for flufenamate ion, are described. This electrode responds to FF with sensitivity of (-58.6 +/- 1.2) mV decade(-1) over the range 1.0 x 10(-6) - 1.0 x 10(-2) mol L-1 at pH 6.0-9.0 and a detection limit of 7.1 x 10(-7) mol L-1. The electrode is easily constructed at a relatively low cost with fast response time (within 10-25 s) and can be used for a period of 5 months without any considerable change in its performance characteristics. The proposed electrode displayed good selectivity for flufenamate in the presence of several substances as well as in the presence of some carboxylate and inorganic anions. The electrode was successfully applied to the determination of flufenamic acid in pharmaceuticals and human serum samples.

Adsorptive potentiometric stripping analysis of nucleic acids at mercury electrodes

The application of adsorptive stripping potentiometry to the reductive detection of nucleic acids at mercury electrodes is reported. Compared to analogous voltammetric stripping modes, constant current potentiometric stripping analysis (PSA) effectively addresses the hydrogen discharge background problem, and hence greatly improves the characteristics of the superimposed cytosine/adenine (CA) reduction peak. Compared to earlier schemes for trace measurements of nucleic acids at mercury or carbon electrodes that rely on anodic signals arising from the guanine residue, convenient quantitation can now be carried out in connection with the cytosine and adenine residues. Variables influencing the adsorptive PSA response are explored and optimized. With five minute accumulation, the detection limits for tRNA, ssDNA and dsDNA are 30 mu g l(-1), 60 mu g l(-1) and 2 mg l(-1), respectively. Such different values reflect the strong dependence of the PSA CA signal upon the nucleic-acid structure. This allows the quantitation of ssDNA or tRNA in the presence of dsDNA, and offers new possibilities for electrochemical studies of DNA structure and interactions.

Use of a carbon paste electrode modified with spinel-type manganese oxide as a potentiometric sensor for lithium ions in flow injection analysis

A potentiometric sensor constructed from a mixture of 25% (m/m) spinel-type manganese oxide (lambda-MnO2), 50% (m/m) graphite powder and 25% (m/m) mineral oil is used for the determination of lithium ions in a flow injection analysis system. Experimental parameters, such as pH of the carrier solution, flow rate, injection sample volume, and selectivity for Li+ against other alkali and alkaline-earth ions and the response time of this sensor were investigated. The sensor response to lithium ions was linear in the concentration range 8.6 x 10(-5) - 1.0 x 10(-2) mol L-1 with a slope 78.9 +/- 0.3 mV dec(-1) over a wide pH range 7 - 10 (Tris buffer), without interference of other alkali and alkaline-earth metals. For a flow rate of 5.0 mL min(-1) and a injection sample volume of 408.6 muL, the relative standard deviation for repeated injections of a 5.0 x 10(-4) mol L-1 lithium ions was 0.3%.

A new potentiometric ibuprofenate ion sensor immobilized in a graphite matrix for determination of ibuprofen in tablets

The characteristics, performance, and application of an electrode, namely, Pt vertical bar Hg vertical bar Hg-2(IBP)(2)vertical bar Graphite, where IBP stands for ibuprofenate ion, are described. This electrode responds to IBP with sensitivity of (58.6 +/- 0.9) mV decade 1 over the range 5.0 x 10(-5)-1.0 x 10(-1) mol L-1 at pH 6.0-9.0 and a detection limit of 3.8 x 10(-5) mol L-1. The electrode is easily constructed at a relatively low cost with fast response time (within 1530 s) and can be used for a period of 5 months without any considerable divergence in potentials. The proposed sensor displayed good selectivity for ibuprofen in the presence of several substances, especially concerning carboxylate and inorganic anions. It was used for the direct assay of ibuprofen in commercial tablets by means of the standard additions method. The analytical results obtained by using this electrode are in good agreement with those given by the United States Pharmacopeia procedure. (c) 2006 Elsevier B.V. All rights reserved.

Benzoate ion determination in beverages by using a potentiometric sensor immobilized in a graphite matrix

The characteristics, performance, and application of an electrode, namely. Pt\Hg\Hg-2(Bzt)(2)\graphite, where Bzt stands for benzoate ion. are described. This electrode responds to Bzt with sensitivity of 57.7 +/- 1.0 mV/decade over the range 5 x 10(-4)-1 x 10(-1) mol l(-1) at pH 6.0-8.0 with a detection limit of 1.6 x 10(-4) mol l(-1). The electrode shows easy construction, fast response rime (between 10-30 s), low-cost, acid excellent response stability (lifetime > 6 months, in continuous use), the proposed sensor displayed good selectivity for benzoate in the presence of several carboxylate and inorganic anions. It was used to determine benzoate in various beverages by means of the standard additions method. The results obtained by using this electrode compared very favorably with those given by the official AOAC spectrophotometric method and by a HPLC procedure as well. (C) 2001 Elsevier B.V. B.V. All rights reserved.

p-Aminobenzoate ion determination in pharmaceutical formulations by using a potentiometric sensor immobilized in a graphite matrix

The characteristics, performance, and application of an electrode, namely, Pt\Hg\Hg-2(PABzt)(2)\ graphite, where PABzt stands for p-aminobenzoate ion, are described. This electrode responds to PABzt with sensivity of (58.1 +/- 1.0) mV per decade over the range 1.0 x 10(-4) to 1.0 x 10(-1) mol l(-1) at pH 6.5-8.0 and a detection limit of 3.2 x 10(-5) mol l(-1). The electrode shows easy construction, fast response time (within 10-30 s), low-cost, and excellent response stability (lifetime greater than 6 months, in continuous use). The proposed sensor displayed good selectivity for p-aminobenzoate in the presence of several substances, especially, concerning carboxylate and inorganic anions. It was used to determine p-aminobenzoate in pharmaceutical formulations by means of the standard additions method. The results obtained by using this electrode compared very favorably with those given by an HPLC procedure. (C) 2004 Elsevier B.V. All rights reserved.

Development of a potentiometric mefenamate ion sensor for the determination of mefenamic acid in pharmaceuticals and human blood serum

The characteristics, performance, and application of a novel and simple electrode, namely Pt vertical bar Hg vertical bar Hg-2(MF)(2)vertical bar Graphite, where MF stands for mefenamate ion, are described. This electrode responds to MF with sensitivity of (58.9 +/- 0.7) mV decade(-1) over the range 1.0 x 10(-6) to 1.0 x 10(-2) mol L-1 at pH 6.0-9.0 and a detection limit of 6.2 x 10(-7) mol L-1. The electrode is easily constructed at a relatively low cost with fast response time (within 10-25 s) and can be used for a period of 4 months without significant change in its performance characteristics. The proposed sensor displayed good selectivity for mefenamate in the presence of several substances, especially concerning carboxylate and inorganic anions. The potentiometric sensor was successfully applied to the determination of mefenamic acid in pharmaceuticals and human serum samples. (c) 2007 Elsevier B.V. All rights reserved.

Determination of diclofenac in pharmaceutical preparations using a potentiometric sensor immobilized in a graphite matrix

The characteristics, performance, and application of an electrode, namely Pt| Hg|Hg-2(DCF)(2)|graphite, where DCF stands for diclofenac ion, are described. This electrode responds to diclofenac with sensitivity of (58.1 +/- 0.8) mV/decade over the range 5.0 x 10(-5) to 1.0 x 10(-2) Mol l(-1) at pH 6.5-9.0 and a detection limit of 3.2 x 10(-5) mol l(-1). The electrode is easily constructed at a relatively low cost with fast response time (within 10-30 s) and can be used for a period of 5 months without any considerable divergence in potentials. The proposed sensor displayed good selectivity for diclofenac in the presence of several substances, especially concerning carboxylate and inorganic anions. It was used to determine diclofenac in pharmaceutical preparations by means of the standard additions method. The analytical results obtained by using this electrode are in good agreement with those given by the United States Pharmacopeia procedures. (c) 2005 Elsevier B.V. All rights reserved.