Quick speciation of iron(ii) and iron(iii) in natural samples using a selective fluorescent carbon dot-based probe†
A new, simple and rapid carbon dot (CD) based fluorescent probe for speciation of Fe2+ and Fe3+ ions was developed. The as-prepared CDs contain phenol groups on their surfaces and due to the special coordination interaction of phenol groups with Fe3+ ions, this sensing system exhibits excellent sensitivity and selectivity toward Fe3+. In order to detect Fe2+ ions as well, a specific amount of H2O2 was introduced to the detection system to transform Fe2+ to Fe3+ of which the latter is the determinable form of iron. Under the optimum experimental conditions, the fluorescence intensity of the sensor decreased as the Fe3+ ion concentration increased. The relationship plot between the fluorescence quenching and Fe3+ ion concentration was linear within the range of 1 to 100 μM and 100 to 500 μM with a detection limit of 0.17 μM. The practical use of the designed nanoprobe in spinach and water samples is also demonstrated successfully.