AbstractIn this study, magnetic polypyrrole/Fe3O4 nanoparticles were synthesized and employed as a novel sorbent for the magnetic solid-phase extraction of chlorpyrifos, an important pesticide used in agriculture. Magnetic solid-phase extraction was carried out together with dispersive liquid−liquid microextraction to enhance enrichment of chlorpyrifos. The effects of various parameters influencing the extraction efficiency, such as sorbent amount, extraction time, and ionic strength, were investigated and optimized. The enrichment factor obtained using the proposed method was 186. The detection limit of the method under optimized conditions was 0.1 µg/L. The relative standard deviation obtained for chlorpyrifos was 9.7% (n = 5) at a concentration level of 5 µg/L. Calibration curve showed linearity in the range of 0.4–40 µg/L for chlorpyrifos. A comparison of the data obtained using the magnetic polypyrrole/Fe3O4 nanoparticles with the data obtained using other sorbents, such as naked Fe3O4 nanoparticles and C18, demonstrated the superior capability of the synthesized composite. The proposed method was also successfully applied to the extraction of chlorpyrifos from well water and river water samples, and satisfactory relative recoveries were obtained.