Differential pulse voltammetric determination of hydroxylamine at an indenedione derivative electrodeposited on a multi-wall carbon nanotube modified glassy carbon electrode

J. Braz. Chem. Soc., Vol. 21, No. 10, 1977-1985, 2010. Printed in Brazil - ©2010 Sociedade Brasileira de Química 0103 - 5053 $6.00+0.00 Hamid R. Zare,* Fatemeh Chatraei and Navid Nasirizadeh Department of Chemistry, Yazd University, 89195-741 Yazd, Iran A eletrodeposição de filmes finos de um derivado da indenodiona em eletrodo de carbono vítreo modificado por nanotubos de carbono de paredes múltiplas (ECV-NTCPM), mostra um par de picos com características de confinamento em superfície. O eletrodo de carbono vítreo modificado por NTCPM e pela indenodiona (ECV-NTCPMI) apresenta uma alta atividade catalítica para a eletro-oxidação de hidroxilamina. O potencial do pico anódico para a oxidação da hidroxilamina em ECV-NTCPMI é aproximadamente 140 mV, enquanto em ECV-NTCPM e em ECV modificado pela indenodiona (ECV-MI), os potenciais de pico aparecem em aproximadamente 505 e 525 mV, respectivamente. Os resultados mostram que há um aumento da corrente do pico anódico de oxidação da hidroxilamina em ECV-NTCPMI quando comparado ao valor obtido com ECV‑MI ou ECV-NTCPM. Os resultados também sugerem que a combinação de NTCPM com um mediador melhora, definitivamente, as características de oxidação da hidroxilamina. Além disso, a voltametria de pulso diferencial exibe dois intervalos dinâmicos lineares de 1,0‑10,0 e 10,0-100,0 µmol L-1 com sensitividade de 0,1955 e 0,0841 µA L µmol-1 respectivamente e um limite de detecção mais baixo, de 0,8 µmol L-1 para hidroxilamina. A excelente reversibilidade eletroquímica do par redox, a simplicidade técnica, e a boa atividade eletrocatalítica para hidroxilamina são as vantagens deste eletrodo modificado. Finalmente, a atividade do ECV-NTCPMI foi também investigada para a determinação da hidroxilamina em duas amostras. The electrodeposited thin films of an indenedione derivative on multi-wall carbon nanotubes modified glassy carbon electrode (MWCNT-GCE) shows one pair of peaks with surface confined characteristics. The indenedione MWCNT modified GCE (IMWCNT-GCE) presents a highly catalytic activity toward hydroxylamine electro-oxidation. The anodic peak potential for hydroxylamine oxidation at IMWCNT-GCE is about 140 mV whereas at MWCNT-GCE and indenedione modified GCE (IMGCE), the peak potentials appear at about 505 and 525 mV respectively. The results show that there is an enhancement of the anodic peak current of hydroxylamine oxidation at IMWCNT-GCE as compared to the value obtained at IMGCE or MWCNT-GCE. The results also suggest that a combination of MWCNT and mediator definitely improves the characteristics of hydroxylamine oxidation. Furthermore, differential pulse voltammetry exhibits two linear dynamic ranges of 1.0-10.0 and 10.0-100.0 µmol L-1 with sensitivity of 0.1955 and 0.0841 µA L µmol-1 respectively and a lower detection limit of 0.8 µmol L-1 for hydroxylamine. Excellent electrochemical reversibility of the redox couple, technical simplicity, and good electrocatalytic activity for hydroxylamine are the advantages of this modified electrode. Finally, the activity of IMWCNT-GCE was also investigated for hydroxylamine determination in two natural samples. Keywords: hydroxylamine, multi-wall carbon nanotubes, modified glassy carbon electrode, indenedione Introduction The electrocatalytic oxidation of hydroxylamine (NH 2OH) has attracted many researches groups. 1-6 *e-mail: , Hydroxylamine is known as a kind of reducing agents, which is widely used in industry and pharmacy. It is identified as a key intermediate in nitrogen cycles and production of nitrous oxide.7 Hydroxylamine is a natural product found in mammalian cells and bacteria. In the former, NH2OH may be formed from decomposition of Article Differential Pulse Voltammetric Determination of Hydroxylamine at an Indenedione Derivative Electrodeposited on a Multi-Wall Carbon Nanotube Modified Glassy Carbon Electrode 1978 Differential Pulse Voltammetric Determination of Hydroxylamine nitrosothiols.8 Moreover, some hydroxylamine derivatives also constitute a great part of anticancer drugs.9 In addition, hydroxylamine has been shown to inactivate or inhibit a number of cellular enzymes and some viruses in vitro. It is also a skin irritant and sensitizer. Numerous methods have been developed for the determination of hydroxylamine.10-23 For example, chromatographic,10 spectrophotometric,11-13 and electrochemical,14-23 methods have been successfully applied to the determination of hydroxylamine. In this regard, we reported the preparation of a coumestan derivative modified carbon paste electrode,19 and a rutin multi-wall carbon nanotubes modified glassy carbon electrode,20 and their application in the electrocatalytic oxidation of hydroxylamine. Also, some recent studies demonstrate the versatility of the use of derivatives nitroso/ hydroxylamine as electrochemical probes for some analytes of biological imprortance.24-27 Due to the unique properties of carbon nanotubes (CNTs) such as high surface area, chemical stability, and high electrical conductivity,28 the application of CNTs in fabrication of electrochemical sensors and biosensors has been studied by many research groups.30-34 The subtle electronic properties of carbon nanotubes suggest that they have the ability to promote electron transfer reaction when used as an electrode material in an electrochemical reaction, which provides a new way in the electrode surface modification for designing new electrochemical sensors.20,29-36 Recently, we have used MWCNT modified electrodes for electrocatalytic determination of some species. 20,29,36,37 Owing to the importance of parahydroquinone ring substituents on the reactivity of the mediator,36 it seems that using an indenedione derivative, with a para-hydroquinone ring in its structure could be important as a modifier and could yield some new information about the catalysis of some slow reactions. We recently described the electrochemical properties of the indenedione derivative MWCNT modified carbon ceramic electrode (IMWCNT-CCE) and its application as a modified electrode for detecting hydrazine.36 In this paper we report the characteristics of another modified electrode which was prepared from the electrodeposition of an indenedione derivative (see Scheme 1 for structure) on MWCNT modified GCE (IMWCNT-GCE). The reactivity of this modified electrode is also examined toward the electrocatalytic oxidation of hydroxylamine with the aim of finding its capabilities as an electron transfer mediator. In this report, we also investigate the electrochemical oxidation of hydroxylamine at MWCNT modified GCE (MWCNT-GCE) and the indenedione derivative modified GCE (IMGCE). The results show that some of the quantitative determination characteristics J. Braz. Chem. Soc. O OH CH3 O CH3 OH Scheme 1. Structure of the indenedione derivative. of hydroxylamine at an IMWCNT-GCE are remarkably improved and also its overpotential is reduced, when compared to MWCNT-GCE and IMGCE. Finally, the (...truncated)