Arginine-derived carbon nanoparticles for determination of Cr(VI) in water samples

Hexavalent chromium, Cr(VI), is a toxic and carcinogenic ion that poses significant risks toward human health and the environment. Due to its extensive industrial use and high water solubility, Cr(VI) can easily contaminate drinking water sources. Therefore, it is essential to develop methods to detect Cr(VI) in water samples. Recently, carbon quantum dots - being biocompatible, easy to synthesize, and cost-effective fluorophores - have been successfully applied for the determination of different heavy metal ions. In this study, arginine-derived carbon nanoparticles were synthesized using a solvent-free one-pot thermal method. These carbon nanoparticles were characterized using transmission electron microscopy, dynamic light scattering analysis, infrared spectroscopy, ultraviolet-visible (UV-vis) light spectroscopy, fluorescence spectroscopy, and CHNO elemental analysis before being used to design a sensor for Cr(VI). The sensor's signal was optimized and the arginine-derived carbon nanoparticle-based Cr(VI) determination method was shown to have a limit of detection of 18 nM, a limit of quantification of 60 nM, and a linear response range of 0.06-100 μM. The sensor's selectivity toward Cr(VI) was studied and a potential interfering ion was identified and dealt with. Finally, the sensor was successfully applied for the determination of Cr(VI) in tap water and mineral water samples.