2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane (CL-20) stands as the most energetically condensed explosive ever found, and poses a great security threat to humans. Here we report a naked-eye colorimetric assay for highly sensitive detection of CL-20. Through effective cascading of the hydrolysis process of CL-20 with nitrite-involved Griess reaction to yield a pink-colored azo product, the visual quantification of CL-20 is realized by taking advantage of corresponding colorimetric signals. Under optimal experimental conditions, the present colorimetric assay is successfully used for highly selective determination of CL-20 in deionized water and environmental water samples with a nanomolar sensitivity. The resulting limit of detection is much lower than conventional methods. Moreover, benefiting from the distinct color change of the detection solution, direct naked-eye semi-quantitative analysis of CL-20 is achieved with a threshold concentration of 1 μM. Such simple, cost-effective, selective, and highly sensitive visual colorimetric assay will have valuable applications in public safety, environmental monitoring, and other related fields.

中文翻译：

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肉眼比色法高灵敏度检测 CL-20 爆炸物

2,4,6,8,10,12-六硝基-2,4,6,8,10,12-六氮杂异武兹烷（CL-20）是迄今为止发现的能量最高的浓缩爆炸物，对人类构成巨大的安全威胁。在这里，我们报告了一种用于高灵敏度检测 CL-20 的肉眼比色测定法。通过将 CL-20 的水解过程与亚硝酸盐参与的格里斯反应有效级联，生成粉红色偶氮产物，利用相应的比色信号实现 CL-20 的可视化定量。在最佳实验条件下，本比色法成功用于去离子水和环境水样品中高选择性测定 CL-20，具有纳摩尔级灵敏度。由此产生的检测限远低于传统方法。此外，受益于检测溶液明显的颜色变化，可以在1 μM的阈值浓度下实现对CL-20的直接肉眼半定量分析。这种简单、经济、选择性和高灵敏度的视觉比色测定将在公共安全、环境监测和其他相关领域具有有价值的应用。