Highly selective and sensitive spectrofluorimetric method for determination of cypermethrin in different environmental samples.

A sensitive, selective, and simple spectrofluorimetric method for the detection and determination of cypermethrin (CYP) in various samples based on thioglycolic acid-caped Mn-doped ZnS quantum dots (TGA@Mn-ZnS-QDs) is reported. These quantum dots were synthesized using the Gonzalez method. The synthesized quantum dots were structurally characterized with the help of different spectroscopic techniques including X-ray diffraction (XRD) and energy dispersive X-ray (EDX) techniques and fluorescence spectroscopy. The quantum dots were used for spectrofluorimetric detection and determination of CYP. The emission peak of these quantum dots at 632 nm showed a linear quenching with increasing the concentration of CYP, noticing an excellent linear relationship between F°/F values and CYP in the range of 0.5-12 µg mL-1 with a correlation coefficient (R2) of 0.992. The influence of different physiochemical parameters such as time, pH, the concentration of quantum dots, and other pesticides interference on the fluorescence quenching was investigated. The detection limit was calculated to be 0.132 µg mL-1. The developed method was successfully applied for the detection and determination of CYP in various spiked samples (tomato, okra, pea, spinach, soil, and water) using the spike and recovery methods. The percent recoveries of CYP from these samples were found to be 77 ± 0.05% to 95 ± 0.12% at various levels.