A convenient and practical colorimetric chemosensor for sulfide monitoring in pure water: Applications to environmental water, smartphone-based platform, colorimetric food imaging and spoilage

Sulfide is an environmentally harmful and toxic substance. Thus, its sensitive detection is important for water-quality monitoring and food safety. In this work, we synthesized a convenient and practical colorimetric chemosensor DNP (1,3-dimethyl-5-(7-nitrobenzo[ c ][1,2,5]oxadiazol-4-yl)pyrimidine-2,4,6(1 H ,3 H ,5 H )-trione) for sensing S 2- in pure water. DNP selectively detected S 2- among varied analytes through color change from red to colorless. The probe DNP showed a low detection limit (2.8 μM) for S 2- in a wide linear range of 0-150 μM, which was significantly below the WHO guideline (14.8 μM). The detecting process of S 2- by DNP was proposed to be a sulfide-triggered reduction of the NBD nitro group, supported by 1 H NMR titration, calculations, and ESI-mass. DNP could certainly quantify S 2- in environmental samples like river water and seawater with recoveries of 98.33% - 103.49%. Also, test-strip and smartphone applications were conveniently applied for S 2- sensing. DNP demonstrated the ability for imaging sulfide in mushroom and onion epidermal cells. In particular, DNP -coated strips could be used as a convenient sulfide indicator of foods such as pork, chicken, and garlic. All these results highlighted DNP as a promising and versatile chemosensor for sulfide detection in food and real-field systems. • A convenient sensor DNP selectively detected S 2- with color change from red to colorless. • Practical DNP could quantify S 2- in environmental samples such as river water and seawater. • Test-strip and smartphone applications were applied for S 2- sensing in water samples. • DNP was able to trace S 2- in various food samples such as pork, chicken, and garlic. • Detection mechanism was demonstrated to be a reduction reaction from -NO 2 to -NH 2 .