| Summary: | This study focused on preparing magnetic silica bio-sorbent made from oil palm fronds and developing methods for analyzing trace amounts of organochlorine pesticides, including Aldrin, Dieldrin, and Heptachlor. The bio-sorbent, namely Fe3O4@SiO2, was prepared through the sol-gel method by combining silica particles derived from oil palm fronds with commercial ferrous (II) oxide. The physical and chemical properties of the bio-sorbents were analyzed using ATR-FTIR, FESEM, EDX, and XRD. According to ATR-FTIR, the bio-sorbent contained absorption bands at 1100 cm-1 and 500-600 cm-1, indicating the functional groups of Si-O and Fe-O. FESEM and EDX studies show the particles have a rough and irregular surface morphology that is composed of 63.9% oxygen, 16.97% silica, and 19.04% ferrous atomic weight. Meanwhile, XRD analysis confirmed that the bio-sorbent was composed of face-centered cubic Fe3O4 and amorphous SiO2, with multiple peaks appearing at 2θ = 22.978 (101), 30.20 (220), 35.60 (311), and 57.50. A magnetic solid-phase extraction method using the synthesized bio-sorbent was developed prior to gas chromatography-mass spectrometry analysis of the selected OCPs. The optimal extraction conditions were determined via one variable at a time (OVAT) and resulted as follows: extraction time, 5 min; desorption solvent, ethyl acetate; desorption time, 5 min; mass of sorbent, 40 mg. The analytical performance of the method was evaluated under these conditions, with a detection limit of 0.1-0.53 mg/L and an extraction recovery of 80-92%. Several linear ranges were obtained for Heptachlor, Aldrin, and Dieldrin, including 0.6-1.8, 0.1-0.3, and 0.2-0.6 mg/L, respectively. The effectiveness of the bio-sorbent was proven by removing pesticides from actual paddy water samples, with calibration curves showing linearity over a wide range of values. The intra-and inter-day precisions were 0.50-1.86% and 0.69-2.54%, respectively. © 2024, Malaysian Society of Analytical Sciences. All rights reserved.
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