A sensing colorimetric method based on in situ formation of gold nanoparticles after dispersive liquid-liquid microextraction for determination of zineb

A novel and highly efficient dispersive liquid-liquid microextraction (DLLME) based on the use of gold nanoparticles (AuNPs) plasmon resonance was developed for the determination of trace amounts of zineb pesticide. The label-free AuNPs as colorimetric probes were synthesized in situ into organic phase using a simple and rapid DLLME procedure. The presence of zineb affected on the plasmon absorbance of AuNPs in sedimented phase which allows the microvolume spectrophotometric sensing of this pesticide. Under the optimal conditions, the method is capable of determining zineb over a range of 0.8-20.0 ng mL− 1 with a limit of detection 0.55 ng mL− 1. The formation of the stable and dispersed AuNPs in organic phase provides a good precision for suggested DLLME method resulting in the relative standard deviation of 4.6 and 1.0% for 8 and 16 ng mL− 1 of zineb, respectively. The method was also successfully applied to the determination of zineb in the environmental samples with the recoveries in the range of 95.6-101.0% for the spiked samples.