Preparation of magnetic molybdenum disulfide for the extraction of neonicotinoid insecticides from environmental water samples

In this study, magnetic molybdenum disulfide hybrid composites (Fe3O4/MoS2) were successfully synthesized by in situ fabrication method and firstly applied as magnetic adsorbent for extracting neonicotinoid insecticides from environmental water samples. The Fe3O4/MoS2 composites were characterized in detail by scanning electron microscope, fourier transform infrared, X-ray diffraction and vibrating sample magnetometer, and possessed the faster adsorption capacity towards neonicotinoid insecticides (only 10 min). The parameters (solution pH, amounts of adsorbents, adsorption time, elution conditions and sample volume) effecting the performance of magnetic solid-phase extraction were carefully investigated. Under the optimal conditions, the magnetic solid-phase extraction-high performance liquid chromatography method based on Fe3O4/MoS2 composites for enriching and detecting neonicotinoid insecticides in environmental water samples was established. The good linearity (0.01-10 mu g/mL) with correlation coefficients between 0.9949 and 0.9999 was obtained. The limits of detection and the limits of quantifications were 0.48-0.67 ng/mL and 1.44-2.02 ng/mL, respectively. With spiked at three different concentration levels (50, 100,500 ng/mL), the recovery was 66.0-91.3 % with relative standard deviations from 1.4 % to 8.3 %. These data demonstrated that the developed method was highly sensitive, repeatable and easily operated. Also, this study provided new adsorbents for other trace pollutants in the environment.