Díaz-González María, Fernández-Sánchez César, Costa-García Agustín
Departamento de Química Física y Analitica, Universidad de Oviedo, 33006 Oviedo, Asturias, Spain.
Anal Sci. 2002 Nov;18(11):1209-13. doi: 10.2116/analsci.18.1209.
Amperometric analysis of indigo carmine at a bare screen-printed electrode placed in an FIA system is reported. This compound is easily detected at a potential of -0.3 V (vs. Ag pseudo-reference electrode) without observing any fouling of the electrode surface, thus allowing the repetitive use of the same electrode in a reproducible manner (coefficients of variation down to 7% for more than 20 consecutive determinations). A linear range of three orders of magnitude and a limit of detection in the sub-micromolar range were attained for this molecule. Based on these studies, indirect amperometric measurements of alkaline phosphatase (ALP) activity in solution were easily carried out using 3-indoxyl phosphate substrate. Its hydrolysis catalyzed by ALP gave rise to indigo product. This product is insoluble in aqueous solutions but it was easily converted into its soluble parent compound, indigo carmine, by addition of fuming sulfuric acid to the reaction media. Using this approach, we achieved a linear range of more than one order of magnitude and a limit of detection of 1 U/l ALP, for an enzymatic reaction time of 60 min.
报道了在流动注射分析（FIA）系统中置于裸屏印刷电极上对靛蓝胭脂红进行安培分析。该化合物在-0.3 V（相对于银伪参比电极）的电位下易于检测，且未观察到电极表面有任何污染，从而允许以可重复的方式重复使用同一电极（连续20多次测定的变异系数低至7%）。该分子实现了三个数量级的线性范围和亚微摩尔范围内的检测限。基于这些研究，使用3-吲哚磷酸底物可轻松进行溶液中碱性磷酸酶（ALP）活性的间接安培测量。其由ALP催化水解产生靛蓝产物。该产物不溶于水溶液，但通过向反应介质中加入发烟硫酸可轻松将其转化为可溶的母体化合物靛蓝胭脂红。使用这种方法，对于60分钟的酶促反应时间，我们实现了超过一个数量级的线性范围和1 U/l ALP的检测限。
