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

Abstract

A simple and cost-effective photoluminescent nanosensor exploitingcarbon dots (CDs) was developed for determination of glyphosatein water samples. The sensing mechanism relied on a CDs/Fe3+system, where the synergy between Fe3+ and glyphosate favouredfluorescence signal quenching as the herbicide concentrationincreased. The CDs were synthesised using an eco-friendlyapproach, employing glucose as the carbon source and polyvinylpyrrolidoneas the surface passivating agent, under microwaveirradiation for 90 s. To further simplify the analytical procedure, anautomated flow-batch system was developed to control nanoparticlehandling and mixing of samples/reagents, thereby minimisinganalyst intervention. The method exhibited satisfactory linearresponse between fluorescence intensity and glyphosate concentrationin the range of 50.0 −500 μg L−1, with a limit of detection of26 μg L−1. Recovery values ranging from 95 to 107% were obtainedfor groundwater and drinking water samples. According to theAGREE metric, the greenness score of the method was 0.59, demonstratingcompliance with green analytical chemistry principles.Overall, this approach provides a rapid, reliable, and efficient alternativefor glyphosate determination in water, without the need forderivatisation or sophisticated instrumentation.