Point-of-Care Testing Kit for the Detection of Hexavalent Chromium by Carbohydrazide-Derived Graphitic Carbon Nitride

Hexavalent chromium (Cr(VI)) ions are among the most common hazardous metals that pose a serious risk to human health, causing human carcinogenesis and chronic kidney damage. In this study, a point-of-care testing (POCT) kit is proposed for Cr(VI) ions detection at room temperature. The kit contains a hydrophobic parafilm, a nylon membrane to resist outflow, and a hydrophilic Whatman filter paper suitable for coating the fluorescent graphitic carbon nitride sheet (g-C3N4). Crystalline, nano-porous, blue-emitting g-C3N4 was produced by pyrolysis utilizing carbohydrazide. The electrostatic interactions between the g-C3N4 and Cr(VI) ions inhibit the fluorescence behavior. The POCT kit can be used for on-site Cr(VI) ion detection dependent upon the blue emission value. The detection limit was attained at 4.64 nM of Cr(VI) ions. This analytical methodology was utilized on real samples from tap, pond, river, and industrial wastewater. This POCT kit can be a useful alternative for on-site detection of Cr(VI) ions.