Novel “on–off” fluorescence sensing for rapid and accurate determination of Cr(3+) based on g-CNQDs

Cr(3+) is one of the most essential trace elements in living organisms and plays a vital role in human metabolism. However, both deficiency and excess intake of Cr(3+) can be harmful to the human body. Therefore, the quantitative determination of Cr(3+) is of great significance in the field of life science. Based on this, in this study, a g-CNQDs@p-acetaminophenol fluorescence sensing system was developed for the quantitative detection of Cr(3+) in actual complex samples. G-CNQDs were synthesized with sodium citrate and urea as precursors. The fluorescence signal was enhanced by the synergistic effect between p-acetaminophenol (APAP) and g-CNQDs. The fluorescence quenching phenomenon can be produced when Cr(3+) is introduced into the fluorescence-enhanced g-CNQDs@p-acetaminophenol system. An “on–off” fluorescence sensing system was constructed based on g-CNQDs@p-acetaminophenol for the quantitative detection of Cr(3+). The experimental data showed a wide linear region in the concentration range of 0.64–63.0 μM, and the detection limit was as low as 0.23 μM. The construction of the sensor system broadens the research field for the practical application of Cr(3+).