Integration of carbon dots with an automated flow-batch system for simple determination of glyphosate in water

A simple and cost-effective photoluminescent nanosensor exploiting carbon dots (CDs) was developed for determination of glyphosate in water samples. The sensing mechanism relied on a CDs/Fe3+ system, where the synergy between Fe3+ and glyphosate favoured fluorescence signal quenching as the herbicide concentration increased. The CDs were synthesised using an eco-friendly approach, employing glucose as the carbon source and polyvinylpyrrolidone as the surface passivating agent, under microwave irradiation for 90 s. To further simplify the analytical procedure, an automated flow-batch system was developed to control nanoparticle handling and mixing of samples/reagents, thereby minimising analyst intervention. The method exhibited satisfactory linear response between fluorescence intensity and glyphosate concentration in the range of 50.0 −500 μg L−1, with a limit of detection of 26 μg L−1. Recovery values ranging from 95 to 107% were obtained for groundwater and drinking water samples. According to the AGREE metric, the greenness score of the method was 0.59, demonstrating compliance with green analytical chemistry principles. Overall, this approach provides a rapid, reliable, and efficient alternative for glyphosate determination in water, without the need for derivatisation or sophisticated instrumentation.