Ultrasensitive optical detection of Fe³⁺ ions using fluorescent carbon quantum dots derived from Simmondsia Chinensis...

We report for the first time the synthesis of carbon quantum dots (CQDs) derived from Simmondsia chinensis (jojoba) leaves using a hydrothermal method at 180 °C for 10 h for ultrasensitive detection of Fe³⁺ ions in aqueous solutions. The obtained CQDs have an average size of 3.5 nm and exhibit stable blue fluorescence, making them suitable for optical sensing applications. They show remarkable selectivity toward Fe³⁺ ions and achieve an ultralow detection limit of 0.018 µM, outperforming most reported CQD-based sensors. The fluorescence quenching behavior follows the Stern-Volmer relation and confirms a static quenching mechanism between Fe³⁺ ions and surface functional groups of the CQDs. These results highlight the potential of jojoba-derived CQDs as low-cost, sustainable, and highly effective fluorescent probes for Fe³⁺ ion detection, offering a promising route for environmental monitoring applications.