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首页> 外文期刊>Electroanalysis >The redox kinetics of adsorbed ATX-I at carbon electrodes by anodic stripping square-wave voltammetry
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The redox kinetics of adsorbed ATX-I at carbon electrodes by anodic stripping square-wave voltammetry

机译：阳极溶出方波伏安法在碳电极上吸附的ATX-I的氧化还原动力学

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The selective adsorptive accumulation of altertoxin I (ATX-I) from a mixture of Alternaria alternata mycotoxins (fungal metabolites) at carbon electrodes is studied by cyclic (CV) and square-wave voltammetry (SWV). The selection of the best experimental reaction medium which minimizes the accumulation rime is analyzed and discussed. The Freundlich adsorption isotherm resulted in being the best one to describe the specific interaction of ATX-I with carbon electrodes by using a fitting procedure of experimental fractional surface coverage vs, the ATX-I bulk concentration (c(ATX-1)*). SWV was also used to generate I-p, vs. c(ATX-1)* calibration plots from pure commercial reagent solutions. A detection limit of 3 x 10(-9)M could be determined from calibration plots performed at f = 100Hz for a signal to noise ratio of 2:1, being this value two orders of magnitude smaller than that obtained previously by us from the diffusion controlled ATX-I oxidation peak. I,lf vs. f plots fi om SW voltammograms performed at different CATX-1* as well as different accumulation times showed the so-called "quasireversible maxima". A splitting of the voltammetric peak was also observed by increasing the SW amplitude at a given frequency. A value of (0.342 +/- 0.003)V was determined for the formal potential of the adsorbed redox couple from the split voltammetric peak. A full characterization of the surface redox process was obtained by applying the methods of "split SW peak" and the "quasireversible maximum". In the 20% acetonitrile (ACN) + 80% 1M HClO4 aqueous solution reaction medium, the formal rate constant and the anodic transfer coefficient were (685 +/- 27) s(-1) and (0.48 +/- 0.03), respectively. Besides, the number of electrons exchanged during the redox reaction was calculated as n approximate to 1. [References: 34]
机译：通过循环（CV）和方波伏安法（SWV）研究了碳链电极上链霉菌真菌毒素的混合物中链霉菌毒素（ATX-1）的选择性吸附积累。分析和讨论了最佳实验反应介质的选择，该介质应最大程度地减少堆积霜。 Freundlich吸附等温线是描述ATX-1与碳电极的特定相互作用的最佳方法，方法是使用实​​验性表面覆盖率相对于ATX-1体积浓度（c（ATX-1）*）的拟合程序。 SWV还用于从纯商业试剂溶液中生成I-p与c（ATX-1）*校准图。对于2：1的信噪比，可以从在f = 100Hz时执行的校准图中确定3 x 10（-9）M的检出限，该值比我们先前从s所获得的值小两个数量级。扩散控制的ATX-1氧化峰。从在不同的CATX-1 *以及不同的累积时间进行的SW伏安图得到的I，lf对f图显示了所谓的“拟可逆最大值”。在给定频率下，通过增加SW振幅也可以观察到伏安峰的分裂。从分离的伏安峰确定吸附的氧化还原对的形式电势的值为（0.342 +/- 0.003）V。通过使用“分裂SW峰”和“拟可逆最大值”的方法获得了表面氧化还原过程的完整特征。在20％乙腈（ACN）+ 80％1M HClO4水溶液反应介质中，形式速率常数和阳极转移系数分别为（685 +/- 27）s（-1）和（0.48 +/- 0.03）。 。此外，氧化还原反应期间交换的电子数被计算为n近似于1。[参考：34]

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