Department of Basic and Applied Science, Zarka University College, Al-Balqa Applied University, Al-Salt, 19117, Jordan.
Department of Analytical Chemistry, Faculty of Chemistry, Oles Honchar Dnipro National University, 49010, Dnipro, Ukraine.
J Pharm Biomed Anal. 2018 Feb 5;149:179-184. doi: 10.1016/j.jpba.2017.11.006. Epub 2017 Nov 6.
A green, simple, accurate and highly sensitive sequential injection lab-at-valve procedure has been developed for the simultaneous determination of ascorbic acid (Asc) and rutin using 18-molybdo-2-phosphate Wells-Dawson heteropoly anion (18-MPA). The method is based on the dependence of the reaction rate between 18-MPA and reducing agents on the solution pH. Only Asc is capable of interacting with 18-MPA at pH 4.7, while at pH 7.4 the reaction with both Asc and rutin proceeds simultaneously. In order to improve the precision and sensitivity of the analysis, to minimize reagent consumption and to remove the Schlieren effect, the manifold for the sequential injection analysis was supplemented with external reaction chamber, and the reaction mixture was segmented. By the reduction of 18-MPA with reducing agents one- and two-electron heteropoly blues are formed. The fraction of one-electron heteropoly blue increases at low concentrations of the reducer. Measurement of the absorbance at a wavelength corresponding to the isobestic point allows strictly linear calibration graphs to be obtained. The calibration curves were linear in the concentration ranges of 0.3-24mgL and 0.2-14mgL with detection limits of 0.13mgL and 0.09mgL for rutin and Asc, respectively. The determination of rutin was possible in the presence of up to a 20-fold molar excess of Asc. The method was applied to the determination of Asc and rutin in ascorutin tablets with acceptable accuracy and precision (1-2%).
一种绿色、简单、准确且高灵敏度的顺序注射阀内实验室方法已被开发出来，用于使用 18-钼-2-磷酸盐 Wells-Dawson 杂多阴离子（18-MPA）同时测定抗坏血酸（Asc）和芦丁。该方法基于 18-MPA 与还原剂之间的反应速率对溶液 pH 的依赖性。只有 Asc 能够在 pH 4.7 下与 18-MPA 相互作用，而在 pH 7.4 时，Asc 和芦丁的反应同时进行。为了提高分析的精度和灵敏度，减少试剂消耗并消除示差效应，顺序注射分析的流路补充了外部反应室，并对反应混合物进行了分段。通过还原剂还原 18-MPA，形成一电子和二电子杂多蓝。在还原剂浓度较低时，一电子杂多蓝的比例增加。在对应等色点的波长处测量吸光度，可得到严格线性的校准曲线。校准曲线在 0.3-24mgL 和 0.2-14mgL 的浓度范围内呈线性，芦丁和 Asc 的检测限分别为 0.13mgL 和 0.09mgL。在 Asc 的摩尔过量高达 20 倍的情况下，仍可测定芦丁。该方法应用于测定抗坏血酸片中的 Asc 和芦丁，具有可接受的准确度和精密度（1-2%）。
