Simple, low-cost, and sensitive methods for the assessment of hexavalent chromium as an important environmental pollutant are highly desirable, especially under resource-limited settings. Therefore, herein we propose an original approach for the simple, low-cost, selective, and extremely sensitive assessment of Cr(VI) utilizing its catalysis of the micellar sensitized o-dianisidine (DA)–hydrogen peroxide reaction. The initial rate of the amended reaction is monitored by tracing the oxidation product, either by a digital camera video recording or spectrophotometrically at 440 nm, for 120 s from mixing the reactants. The optimized reaction conditions were 5 mmol L⁻¹ DA, 0.6 mol L⁻¹ H₂O₂, 2.0 v/v% Tween 20, and 10 mmol L⁻¹ chloroacetate buffer (pH 4.5 ± 0.1), at 30 °C. The linear calibration graph extends to 90.0 ng mL⁻¹ Cr(VI) with detection limits (3S_b) of 0.8 and 1.0 ng mL⁻¹, for the video recording and spectrophotometric procedures, respectively. The amended method was successfully applied to the assessment of Cr(IV) in natural and polluted industrial wastewaters. The analytical data were in excellent statistical harmony with those of the standard ETAAS method. The proposed method is two orders of magnitude more sensitive than the diphenylcarbazide standard spectrophotometric method.

Graphical abstract

非常需要一种简单，低成本和灵敏的方法来评估六价铬作为一种重要的环境污染物，尤其是在资源有限的环境下。因此，本文中我们提出了一种利用Cr（VI）对胶束敏化的O- dianisidine（DA）-过氧化氢反应的催化，对Cr（VI）进行简单，低成本，选择性和极其灵敏的评估的原始方法。通过数码相机录像或在440 nm处用分光光度法跟踪氧化产物，跟踪混合产物的120 s，从而监测修饰反应的初始速率。优化的反应条件为5 mmol L ^-1 DA，0.6 mol L ^-1 H ₂ O ₂，2.0 v / v％Tween 20和10 mmol L ^-1氯乙酸缓冲液（pH 4.5±0.1），在30°C下。线性校准图扩展至90.0 ng mL ^-1 Cr（VI），检测限（3S _b）分别为视频记录和分光光度法，分别为0.8和1.0 ng mL ^-1。修正后的方法已成功应用于自然和污染工业废水中六价铬的评估。分析数据与标准ETAAS方法具有极佳的统计一致性。所提出的方法比二苯卡巴肼标准分光光度法的灵敏度高两个数量级。

图形概要