Detection of metolachlor in grain by N-doped carbon quantum dots

Abstract

Abstract To achieve rapid detection of metolachlor in grain, nitrogen was doped into carbon quantum dots (N-CQDs) by a hydrothermal method, and the morphological features, elemental compositions and optical properties of the N-CQDs were analyzed and investigated by transmission electron microscopy, X-ray photoelectron spectroscopy, and fluorescence spectroscopy, respectively. Based on the principle of intramolecular charge transfer (ICT), a fluorescent probe was constructed for the rapid detection of metolachlor. Under the optimal experimental conditions, the fluorescence intensity change values of N-CQDs and metolachlor concentration had a good linear relationship when the concentration of metolachlor was in the range of 0.0125-2.5 µg/mL. The evaluation of the method showed that the method has good selectivity, reproducibility and stability, with the limit of detection (LOD) of 1.63 µg/kg and the limit of quantification (LOQ) of 3.92 µg/kg. The spiked recoveries of the six real samples were tested using a spiked recovery assay, which yielded spiked recoveries in the range of 105.05%~87.13%, and their relative standard deviations (RSD, n = 3) ranged from 4.62–0.61%, indicating that the method can be used in the detection of practical samples with good precision and stability.