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.