Chitosan composited covalent organic framework nanoparticles for the dispersive micro-solid-phase extraction of chlorpyrifos pesticide from environmental water samples prior to spectrophotometric determination

Abstract

In this study, chitosan (CS), as a green, low- or negligible toxic, low-cost, biocompatible, biodegradable, and environmentally friendly compound, was composited with covalent organic framework (COF) nanoparticles. Following the synthesis, the nanocomposite (COF-CS) was characterized and identified by diverse techniques such as Fourier-transform infrared spectroscopy (FT-IR), field emission-scanning electron microscopy-energy dispersive spectroscopy (FESEM-EDS), and Brunauer-Emmett-Teller (BET) surface area analysis. The COF-CS was subsequently employed for dispersive micro-solid-phase extraction (D-µ-SPE) of the chlorpyrifos (CPF) pesticide from environmental water samples prior to spectrophotometric determination. The factors that affect the extraction process were examined and optimized through the application of central composite design-based response surface methodology (CCD-RSM). The primary benefit of the COF-CS nanocomposite lies in its ability to address several significant limitations of CS, including its inadequate adsorption capacity, limited specific surface area, and low stability. Moreover, the COF-CS nanocomposite has the potential to resolve the primary issues associated with COF nanoparticles, specifically their propensity for aggregation and the challenges in separation due to their low density. Another key benefit of the COF-CS nanocomposite is that it provides multiple interaction sites, including hydrogen bonding and π-π interaction with CPF, to further improve the extraction efficiency. According to the CCD-RSM, the optimum parameters were pH (4.5), elution volume (300 µL of methanol), sorbent dosage (10 mg), and extraction time (12 min). Under the optimized conditions, the linear range of the method was from 10.0 to 700.0 µg L⁻¹. In addition, the limit of detection of the method was achieved to be 3.9 µg L⁻¹.