Ghoneim M M, El-Ries M, Hassanein A M, Abd-Elaziz A M
Chemistry Department, Faculty of Science, Tanta University, Tanta, Egypt.
J Pharm Biomed Anal. 2006 Jun 16;41(4):1268-73. doi: 10.1016/j.jpba.2006.03.022. Epub 2006 May 9.
The electrochemical behavior of the anthelmintic veterinary drug nitroxynil at the mercury electrode was studied in a series of Britton-Robinson universal buffer of pH 1.9-11 containing 20% (v/v) ethanol using dc-polarography cyclic voltammetry and controlled-potential coulometry. The voltammograms exhibited two irreversible cathodic steps over the pH range 1.9-10.2; the height of the first step is double that of the second one. Controlled-potential coulometry in the B-R universal buffer of pH 1.9-10 at a mercury pool working electrode revealed the consumption of four and two electrons via the first and second reduction steps, respectively, which attributed to reduction of the NO2 group to the hydroxylamine stage (first step), and then to the amine stage (second step). Three voltammetric analytical procedures including dc-polarography, differential-pulse adsorptive stripping voltammetry and square-wave adsorptive stripping voltammetry were optimized for the direct determination of bulk nitroxynil. The three proposed procedures were applied for analysis of bulk nitroxynil with limits of detection of 3 x 10(-5), 1.31 x 10(-8) and 8.4 x 10(-10)M and limits of quantification of 1 x 10(-5), 4.36 x 10(-8) and 2.80 x 10(-9)M, respectively. The three procedures were successfully applied to the determination of nitroxynil in formulation (Dovenix, 25% nitroxynil injection solution) without the necessity for sample pretreatment and/or time-consuming extraction steps prior to the analysis.
在一系列含有20%（v/v）乙醇、pH值为1.9 - 11的Britton-Robinson通用缓冲溶液中，使用直流极谱法、循环伏安法和控制电位库仑法研究了驱虫兽药硝碘酚腈在汞电极上的电化学行为。伏安图在pH值1.9 - 10.2范围内呈现出两个不可逆的阴极步骤；第一步的高度是第二步的两倍。在pH值为1.9 - 10的B - R通用缓冲溶液中，在汞池工作电极上进行的控制电位库仑法表明，通过第一步和第二步还原步骤分别消耗了四个和两个电子，这归因于NO₂基团先还原为羟胺阶段（第一步），然后再还原为胺阶段（第二步）。优化了三种伏安分析方法，包括直流极谱法、差分脉冲吸附溶出伏安法和方波吸附溶出伏安法，用于直接测定硝碘酚腈的总量。所提出的三种方法用于分析硝碘酚腈总量，检测限分别为3×10⁻⁵、1.31×10⁻⁸和8.4×10⁻¹⁰ M，定量限分别为1×10⁻⁵、4.36×10⁻⁸和2.80×10⁻⁹ M。这三种方法成功应用于制剂（Dovenix，25%硝碘酚腈注射液）中硝碘酚腈的测定，无需在分析前进行样品预处理和/或耗时的萃取步骤。
