Mohamed, Ahmad Husaini (2023) Development Of Functionalized Oil Palm Empty Fruit Bunch-based Magnetic-carboxymethyl Cellulose Nanofibers Composite For The Magnetic Solid-phase Extraction Of Organophosphorus Pesticides. PhD thesis, Universiti Sains Malaysia.
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Abstract
The abusive use of organophosphorus pesticides (OPPs) chemical has caused serious public health issues and can lead to contamination of the environment. The generally low levels of OPP residues and often the complexity of the matrix, such as environmental waters and vegetables, are the concerns that researchers must deal with. In response to this, it is vital to develop a sensitive, selective, and efficient sample preparation and analytical method to determine the concentration of OPPs in complex matrices. Various sample preparation techniques have been integrated with instrumentation which can overcome drawbacks experienced by the classical methods by establishing longer longevity, simple procedure, excellent extraction selectivity, and environmental friendly. For that reason, a new functionalized oil palm empty fruit bunch-based magnetic-carboxymethyl cellulose nanofibers composite was synthesized to be used in magnetic-solid phase extraction (MSPE) for analysis of selected OPPs in environmental water, lettuce, and celery vegetable samples. This composite was fabricated from the incorporation of carboxymethyl cellulose nanofibers extracted from oil palm empty fruit bunch (OPEFB), magnetic nanoparticles (Fe3O4 MNPs), and imidazolium-based ionic liquid (IL) via three steps processes (carboxymethylation, sol-gel, and grafting copolymerization). The OPEFB biomass residue was started with pre-treatment followed by combining chemical (sodium hydroxide (NaOH) alkaline) and mechanical (homogenization and ultrasonication) treatment protocols producing cellulose nanofibers (CNF). The prepared magnetic-carboxymethyl cellulose nanofibers (Fe3O4-cmCNF) and magnetic-carboxymethyl cellulose nanofibers grafted PIL (Fe3O4-cmCNF-g-poly(3Ph1VImBr)) have been characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR), vibrating sample magnetometer (VSM), Brunauer-Emmett-Teller (BET) analysis, X-ray diffraction (XRD), and thermogravimetric analysis (TGA). Determination and quantification of OPPs were obtained using a gas chromatography-micro electron capture detector (GC-μECD). An MSPE method based on Fe3O4-cmCNF was developed to determine the trace concentration of diazinon, fenitrothion, and malathion in environmental water. Under optimum conditions, the linearity range was achieved between 0.1 to 200 ng mL-1 with good determination coefficient (r2 > 0.9962). The proposed method allows the determination of OPPs with limits of detection (LODs) at 0.03 ng mL-1 and required a short extraction time (3 min) as well as low organic solvent consumption (0.2 mL). The successful extraction was proved with a good relative recoveries range of 81.8–119.6 % with precision (RSDs) between 1.7 to 14.0 %. Next, the optimized Fe3O4-cmCNF-g-poly(3Ph1VImBr)-MSPE was successfully applied to determine six selected OPPs (dichlorvos, diazinon, tolclofos-methyl, fenitrothion, malathion, and chlorpyrifos) in lettuce and celery samples. The method displayed matrix-matched linearity curves over a concentration range of 0.1 to 250 μg kg-1 (r2> 0.9954), low LODs (0.01-0.07 μg kg-1), and good relative recoveries in the range of 81-117% (RSDs 14%). The established MSPE techniques hyphenated with gas chromatography have proved to be beneficial and offer a sensitive, simple sample preparation process, less consumption of toxic organic solvent, environmentally friendly, and appropriate for the determination of OPPs in real sample matrices.
| Item Type: | Thesis (PhD) |
|---|---|
| Subjects: | R Medicine > R Medicine (General) |
| Divisions: | Institut Perubatan & Pergigian Termaju (Advanced Medical & Dental Institute (AMDI)) > Thesis |
| Depositing User: | MUHAMAD AMIN BIN AZMI |
| Date Deposited: | 04 May 2026 01:50 |
| Last Modified: | 04 May 2026 01:50 |
| URI: | http://eprints.usm.my/id/eprint/64041 |
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