Vortex-assisted dispersive micro-solid-phase extraction using silica-supported Fe₂O₃-modified khat (Catha edulis) biochar nanocomposite followed by GC-MS for the determination of organochlorine pesticides in juice samples

Abstract

In this paper, dispersive micro-solid phase extraction technique was developed for the purpose of extracting and preconcentrating organochlorine pesticide residues in juice samples before their separation and quantitative analysis by gas chromatography-mass spectrometry. A sorbent composed of a silica-supported Fe₂O₃-modified khat leftover biochar nanocomposite (SiO₂-Fe₂O₃-KLBNC) was implemented in the process. To improve the dispersion of the sorbent in the solution, vortex mixer was employed. Experimental parameters influencing the performance of the method were optimized, and the optimal conditions were established. With these conditions, linear dynamic ranges ranged from 0.003 to 100.0 ng/mL were achieved, with a correlation coefficient (r²) ≥ 0.9981. The limits of detection and quantification, determined by signal-to-noise ratios of 3 and 10, respectively, were found to be in the ranges of 0.001–0.006 ng/mL and 0.003–0.020 ng/mL. Intra- and inter-day precision, values ranging from 0.3–4.8% and 1.7–5.2% were obtained, respectively. The matrix-matched extraction recoveries demonstrated favorable outcomes, falling within the range of 83.4–108.3%. The utilization of khat leftover as an adsorbent in contemporary sample preparation methodologies offers a cost-effective alternative to the currently available, yet expensive, adsorbents. This renders it economically viable, particularly in resource-constrained regions, and is anticipated to witness widespread adoption in the coming future.

Keywords:

• Dispersive micro-solid phase extraction
• gas chromatography-mass spectrometry
• juice samples
• organochlorine pesticides
• silca-supported-Fe₂O₃-modified biochar nanocomposite

Acknowledgments

The authors are grateful to the Department of Chemistry in the College of Natural Sciences, at Jimma University for their material support. The authors would also like to acknowledge Jinka University for sponsoring K. A. Ago’s PhD study.

Authors’ contributions

Kero Assefa Ago: Conceptualization, Investigation, experimental work, writing an original draft, preparing revision, Data curation, Formal analysis, preparing a manuscript; Shimelis Addisu Kitte: Supervision, Data curation, Software, Writing review & editing; Abera Gure: Project administration, Funding acquisition, Resources, Investigation, Supervision, Writing, Review & editing; Jemere Kochito: Data curation, Writing review & editing; Yerosan Buzayo: Investigation, experimental work, preparing revision.

Data availability statement

The data that support the findings of this study are available from the corresponding author on reasonable request.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported by the College of Natural Sciences, Jimma University through the grand research project (CNS-Chem-11-2020/21-SP1).