Magnetic solid-phase extraction of five pyrethroids from environmental water samples followed by ultrafast liquid chromatography analysis

In this study, the polystyrene-coated magnetic nanoparticles (MNPs/PSt) were successfully prepared and characterized by Fourier transform infrared spectroscopy, transmission electron microscopy and vibrating sample magnetometry. The as-prepared MNPs/PSt were used as the adsorbent in magnetic solid phase extraction of five pyrethroids, including lambda-cyhalothrin, deltamethrin, esfenvalerate, permethrin, bifenthrin, in environmental water samples. The five pyrethroids were determined by ultra fast liquid chromatography-ultraviolet spectrometry. The influencing factors, including amount of MNPs/Pst, extraction time, pH value, type and volume of desorption solvent and desorption time, were examined and optimized. The extraction recoveries obtained with merely 50 mg of MNPs/Pst were very satisfactory. The whole extraction process could be completed within 0.5 h. The MNPs/PSt can be reused after an easy washing process. Thus, a simple, green, economical, time saving and effective method for pyrethroids analysis in environmental water samples was established. A high enrichment factor of 500 was achieved and the limits of detection for lambda-cyhalothrin, deltamethrin, esfenvalerate, permethrin, bifenthrin were 0.015±0.001 ng mL−1, 0.012±0.001 ng mL−1, 0.026±0.001 ng mL−1, 0.020±0.001 ng mL−1, 0.013±0.001 ng mL−1, respectively. Recoveries obtained by analyzing spiked water samples at three concentration levels (0.100±0.001 ng mL−1, 1.000±0.001 ng mL−1, 10.000±0.001 ng mL−1) were between 78.97±8.38% and 96.05±8.38%. The standard curves for the five pyrethroids showed good linearity with the correlation coefficients in the range of 0.9994–0.9999. The intra-day and inter-day precision were satisfactory with the RSDs in the range of 2.05–5.52% and 2.73–8.38%, respectively.