High luminescent carbon dots as an eco-friendly fluorescence sensor for Cr(VI) determination in water and soil samples

- The pyrolysis method was suitable to produce CDots with intense luminescence.
- The CDots displayed high photoluminescence quantum yield of 69%.
- CDots and Cr(VI) interaction is associated with inner filter effect and static quenching.
- The method employed presenting a linear range from 0.10 to 12 μg mL−1.
- The method was selective, sensitive and versatile in different environmental samples.

In this work were synthesized highly luminescent carbon dots for use as fluorescence sensor for Cr(VI). Carbon dots (CDots) were prepared by pyrolysis of the mixture of molecular precursors as citric acid and reduced glutathione. Pyrolysis revealed to be a simple procedure that afforded CDots with a photoluminescence quantum yield of 69.4%, and particle size of about 2.5 nm. To explore the analytical potentiality of the nanomaterial produced, the CDots were applied as fluorescent sensors to determine Cr(VI) in water and soil samples. The interaction mechanism between CDots and Cr(VI) is associated with both inner filter effect and static quenching. After optimization of the main analytical parameters, the method showed a linear range of 0.10-12 μg mL−1 with limit of detection (LOD) of 0.03 μg mL−1 (pH 7), and recoveries of 90-105% and 99.5-107% for samples of water and soil, respectively. Thus, the method proved to be sensitive, fast and versatile for applications in different environmental samples.

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