Portable smartphone-based device for on-site detection of Hg²⁺ in water samples

In this paper, a smartphone-based portable device was designed for on-site and real-time detection of Hg²⁺ concentration levels in water samples. A rhodaminespirolactam-based derivative3ʹ,6ʹ-bis(diethylamino)-2-((3,4,5-trimethoxybenzylidene)amino)spiro[isoindoline-1,9ʹ-xanthen]-3-one, which had selective response to Hg²⁺,was used as Off-On fluorescent probe. The enhanced emission was observed by a high-pixel camera integrated on the smartphone. The grey value was analysed by an android/apple application ‘Detection’, and showed good linearly with Hg²⁺ concentration ranged from 0.01 to 0.1 μg/ml. The limit of detection (LODs) was found at 0.9 μg/l, which was sensitive enough to detect Hg²⁺ in industrial wastewater and drinking water. The accuracy of the proposed method was validated by reference Hg²⁺ solution, and the result was in good agreement with the certified value. Compared with cold vapour atomic fluorescence spectrophotometry, atomic absorption spectrophotometry methods and fluorescence method, etc., the developed platform is simpler, cost-less and portable for on-site and real-time application, and can be used for sharing of in-field sensing data from any remote location to the central water quality monitoring station.本文设计了一款基于智能手机的便携式检测装置，可实现水样中汞离子（Hg²+）浓度的现场实时检测。本研究采用一种基于罗丹明螺内酰胺（rhodaminespirolactam）的衍生物3',6'-二(二乙氨基)-2-((3,4,5-三甲氧基苯亚甲基)氨基)螺[异吲哚啉-1,9'-呫吨]-3-酮作为关开型（Off-On）荧光探针，该探针对Hg²+具有选择性响应。借助智能手机集成的高像素摄像头，可观测到探针的荧光发射增强信号。通过安卓/苹果端应用程序‘Detection’对图像灰度值进行分析，结果显示其与0.01~0.1 μg/mL浓度范围内的Hg²+具有良好的线性相关性。本方法的检出限（LOD）为0.9 μg/L，该检测灵敏度足以满足工业废水与饮用水中Hg²+的检测需求。采用标准Hg²+溶液对本方法的准确度进行了验证，测试结果与标准参考值具有良好的一致性。相较于冷蒸气原子荧光分光光度法、原子吸收分光光度法及传统荧光法等现有检测手段，本研究所开发的检测平台操作更简便、成本更低且便携性更强，可实现现场实时检测，并支持将任意远程点位的现场传感数据上传至中央水质监测站进行共享。