Determination of nitrite in food samples by anodic voltammetry using a modified electrode

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)A glassy carbon (GC) electrode modified with alternated layers of iron(III) tetra-(N-methyl-4-pyridyl)porphyrin (FeT4MPyP) and copper tetrasulfonated phthalocyanine (CuTSPc) was employed for nitrite determination by differential pulse voltammetry (DPV). This modified electrode showed excellent catalytic activity for the nitrite oxidation. After optimizing the operational conditions, a linear response range from 0.5 to 7.5 mu mol l(-1) with a low detection limit of 0.1 mu mol l(-1) was obtained. The proposed sensor was stable with a sensitivity of 20.0 mu A, 1 mu mol(-1) and good repeatability, evaluated in terms of relative standard deviation (R.S.D. = 1.3%) for n = 10. Possible interferences from several common ions were evaluated. This sensor was applied for the voltammetric determination of nitrite in some food samples. The results were consistent with those obtained with the standard spectrophotometric procedure. (C) 2008 Elsevier Ltd. All rights reserved.113412061211Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq

Amperometric sensor for nitrite based on copper tetrasulphonated phthalocyanine immobilized with poly-L-lysine film

In this work, an amperometric sensor for nitrite detection based on a glassy carbon electrode modified with copper tetrasulphonated phthalocyanine immobilized by polycationic poly-L-lysine film is presented. The modified electrode showed an excellent catalytic activity toward nitrite oxidation. linear response range from 0.12 up to 12.20 mu mol L-1 was obtained with a sensitivity of 0.83 mu A L mu mol(-1). The detection limit for nitrite was 36 nmol L-1. The repeatability of the proposed sensor, evaluated in terms of relative standard deviation, was 1 % for 10 measurements of 10 mu mol L-1 nitrite solution. Finally, the developed sensor was applied for nitrite determination in water samples and the results were in agreement to the comparative method. The average recovery for the samples was 101 (+/- 4)%. (c) 2008 Published by Elsevier B.V.75233333

Amperometric sensor for nitrite using a glassy carbon electrode modified with alternating layers of iron(III) tetra-(N-methyl-4-pyridyl)-porphyrin and cobalt(II) tetrasulfonated phthalocyanine

The development of a highly sensitive amperometric sensor for nitrite using a glassy carbon electrode modified with alternated layers of iron(III) tetra-(N-methyl-4-pyridyl)-porphyrin (FeT4MPyP) and cobalt(II) tetrasulfonated phthalocyanine (CoTSPc) is described. The modified electrode showed an excellent catalytic activity and stability for the nitrite oxidation decreasing the peak potentials about 200 mV toward less positive values and presenting much higher peak currents than those obtained on the bare GC electrode. A linear response range of 0.2-8.6 mu mol l(-1), with a sensitivity of 0.37 mu A I mu mol(-1) and detection limit of 0.04 mu mol l(-1) were obtained with this sensor. The repeatability of the proposed sensor, evaluated in term of relative standard deviation, was verified to be 1.4% for 10 measurements of 0.2 mu mol l(-1) nitrite solution. Interference caused by common ions has been investigated in simulated mixtures containing high concentration level of interfering ions and the sensor was found to be tolerant against these ions. The developed sensor was applied for the nitrite determination in water samples and the results were in agreement with those obtained by a comparative method described in the literature. The average recovery for these samples was 100.1 (+/- 0.7)%. (c) 2006 Elsevier B.V. All rights reserved.70358859

An amperometric sensor based on electrochemically triggered reaction: Redox-active Ar-NO/Ar-NHOH from 4-nitrophthalonitrile-modified electrode for the low voltage cysteine detection

The present work describes the development of a highly sensitive amperometric sensor based on a simple and efficient carbon paste electrode modified with a new redox "mediator", 4-nitrophthalonitrile, toward detection of cysteine (CySH) in neutral medium at an applied potential of 0.33 V vs. Ag/AgCl. The sensor showed its best performance in 0.1 mol L-1 phosphate buffer solution, at pH 7.0. After optimizing the operational conditions, the sensor provided a linear response range for CySH from 0.8 up to 13.2 mu mol L-1 with sensitivity, detection and quantification limits of 37 nA L mu mol(-1), 0.25 mu mol L-1 and 0.80 mu mol L-1, respectively. The sensitivity of the proposed sensor was much higher when compared to other sensors described in the literature and showed a stable response for at least 80 successive determinations. The repeatability of the measurements with the sensor and the preparation of a series of electrodes, evaluated in terms of relative standard deviation, were 4.1 and 5.0%, respectively, for n = 10. The developed sensor was applied for cysteine determination in food supplement samples and the results were statistically the same with those obtained by the comparative method described in the literature at a confidence level of 95%. (c) 2007 Elsevier B.V. All rights reserved.6121879