Qualitative and quantitative detection of cyanide in forage crop and fibre dietary products by colorimetric and fluorescent sensor based on corn silk derived carbon dots-rutin system.

Abstract

Cyanide is the most fatal anion which is also an inevitable component present in edible parts such as leaves and kernels of many plants, therefore the detection and quantification of cyanide in food is vital. Herein, we have developed a turn off fluorescent sensor using a novel fluorescent probe with carbon dots and rutin combination system. Blue emission carbon dots have been derived from lignin rich corn silk through a single step hydrothermal synthesis. The synthesized carbon dots displayed maximum fluorescence emission at 400 nm upon excitation at 320 nm. The developed sensor exhibits good linearity in the range of 500 nM to 50 μM with the lowest detection limit of 459 nM. A specific binding site in rutin that facilitates nucleophilic addition of cyanide has been unveiled for the first time. The nucleophilic addition mechanism resulted in quenching of fluorescence emission at 400 nm due to hindered intramolecular charge transfer in rutin. Further, this mechanism is followed by the solvochromatic effect which leads to colour change of the system from colourless to yellowish green along with a bathochromic shift of the emission peak. This phenomenon enables the qualitative analysis of cyanide through colorimetric detection. Besides, the interaction of cyanide with rutin through a weak hydrogen bonding has been evaluated using electrochemical detection method. Thus, a triple mode (fluorescent, colorimetric and electrochemical) detection of cyanide effectively using a single probe has been accomplished. Successfully, the fabricated sensor is utilized to investigate the presence of cyanide in sorghum leaves, flaxseeds, cassava, almond and gold industrial effluents.