New magnetic oil palm fiber activated carbon-reinforced polypyrrole solid phase extraction combined with gas chromatography-electron capture detection for determination of organochlorine pesticides in water samples.

•Low-cost oil palm fiber waste (OPAC) used as sorbent base in extraction (OCPs).•OPAC modified with magnetite and polypyrrole to produce OPAC-Fe3O4-PPy composite.•OPAC-Fe3O4-PPy used as new magnetic solid phase extraction (MSPE) sorbent.•Facile OPAC-Fe3O4-PPy synthesis and MSPE–GC-μECD optimized using box-behnken design.•Low LOD at ppt level and high pesticides (OCPs) recoveries from water samples.