Orange ratiometric fluorescent probe for sensitive detection of phoxim

Pesticides are chemicals widely utilized in various industries, particularly agriculture, to manage pests and enhance crop yields. However, the excessive use of pesticides, such as phoxim, poses threats to the environment, food safety, and human health. Thus, it is crucial to use pesticides judiciously, limiting their application to what is necessary. Fluorescent probes have garnered attention for their cost-effectiveness, straightforward preparation, and high sensitivity, positioning them as promising candidates for detecting phoxim. In this context, orange ratiometric fluorescent carbon dots were synthesized using Rhodamine B and NaOH as precursors through a hydrothermal method. The synthesized Rh BNa CDs were then purified via dialysis, thin-layer chromatography, and chromatographic columns to develop an accurate and precise ratiometric fluorescent probe. This nanoprobe demonstrated excellent linear ranges for detecting phoxim levels in various food samples. It exhibited a low detection limit of 4.486 nM for phoxim concentrations ranging from 0 to 25 μM and can accurately detect concentrations between 25 and 250 μM. Moreover, it proved sensitive in identifying phoxim content in samples of red grapes, green grapes, tomatoes, and pitayas.