AbstractA method is described for the colorimetric determination of chromate [chromium(VI)]. It is based on the use of graphene oxide (GO) nanoparticles acting as a peroxidase mimic. A blue color is generated by oxidation of 3,3,5,5-tetramethylbenzidine by H2O2 which is catalyzed by GO. This color-forming reaction is prevented in the presence of 8-hydroxyquinoline (8-HQ). However, in the presence of Cr(VI), the blue color will be formed from TMB owing to the oxidation of the inhibitor 8-HQ by Cr(VI). The color can be measured by a spectrophotometry (at 652 nm) or detected visually. Under optimal experimental conditions, response is linear in the 50 to 430 nM range of chromate concentration, and the limit of detection is 5.8 nM (at S/N = 3). The assay is highly selective and was successfully applied to the determination of Cr(VI) in spiked water samples. Graphical abstractSchematic of the colorimetric assay for Cr(VI). TMB: 3,3,5,5-tetramethylbenzidine

中文翻译：

---

使用氧化石墨烯纳米颗粒作为过氧化物酶模拟催化剂和 8-羟基喹啉作为抑制剂的比色检测六价铬

摘要 描述了一种比色测定铬酸盐[六价铬]的方法。它基于使用氧化石墨烯 (GO) 纳米粒子作为过氧化物酶模拟物。GO 催化 H2O2 氧化 3,3,5,5-四甲基联苯胺，产生蓝色。在 8-羟基喹啉 (8-HQ) 的存在下可以防止这种颜色形成反应。然而，在 Cr(VI) 存在下，由于抑制剂 8-HQ 被 Cr(VI) 氧化，TMB 会形成蓝色。颜色可以通过分光光度法（在 652 nm）测量或视觉检测。在最佳实验条件下，响应在 50 至 430 nM 铬酸盐浓度范围内呈线性，检测限为 5.8 nM（S/N = 3）。该测定具有高度选择性，已成功应用于测定加标水样品中的 Cr(VI)。Cr(VI) 比色测定的图形摘要示意图。TMB：3,3,5,5-四甲基联苯胺