Modified magnetic chitosan nanoparticles based on mixed hemimicelle of sodium dodecyl sulfate for enhanced removal and trace determination of three organophosphorus pesticides from natural waters.

Mixed hemimicelle SDS-coated magnetic chitosan nanoparticles (MHMS-MCNPs) were utilized as an efficacious adsorbent for both removal and preconcentration of pesticides named diazinon, phosalone and chlorpyrifos. In this method, the formation of mixed hemimicelles made up of SDS on the surface of MCNPs leads to solubilization and the retention of target analytes by strong hydrophobic and electrostatic interactions, which has been realized for the first time in magnetic chitosan nanoparticles support. Different parameters affecting the adsorption of pesticides were optimized as rFemoval efficiency by response surface methodology and one variable at a time. Under the optimum condition, adsorption equilibrium data were fitted well to the Langmuir isotherm. Extraction recoveries for 5 ng mL-1 of diazinon, phosalone and chlorpyrifos were 99%, 98% and 96%, respectively; with relative standard deviations values were lower than 4.6% for five replications of extraction. Limit of detection obtained for mentioned pesticides were <0.09 ng mL-1. Eventually, MHMS-MCNPs were successfully applied for both removal and trace determination of pesticides in surface and ground environmental and waste water samples collected from various places in northern Iran.