Vortex-assisted dispersive microsolid-phase extraction method for preconcentration of cobalt and nickel in real samples prior to their flame atomic absorption spectrometric detection

A straightforward and validated vortex-assisted dispersive microsolid-phase extraction method for the separation and preconcentration of cobalt and nickel ions in real samples (water, juice, and food) prior to their determination by flame atomic absorption spectrometry (FAAS) was developed. The suggested technique utilizes adsorbent, modified multiwalled carbon nanotubes, in conjunction with a new complexing agent, 3-benzyl-4-p-nitrobenzylidenamino-4,5-dihydro-1,2,4-triazole-5-thiol, which complexes with cobalt and nickel ions at pH 7.0. The impact of various parameters has been examined and refined. The calibration curves exhibited linearity throughout the ranges of 2.0–500 and 5.0–400 μg L−1, with limit of detections of 0.60 and 1.5 μg L−1 for cobalt and nickel ions, respectively, under optimal circumstances. The preconcentration factor was 200. Cobalt and nickel have maximum sorption capacities of around 400 and 450 mg g–1, respectively. The recovery rates of the analytes varied between 95.0% and 100%. Additionally, the relative standard deviation (RSD%) for intra-day (1.80% and 2.40%) and inter-day (1.50% and 2.0%) measurements indicates the repeatability for determination of cobalt and nickel ions, respectively. Certified reference materials were employed to validate the precision of the suggested preconcentration process. The suggested method effectively determined the concentrations of cobalt and nickel ions in several real environmental samples. KEY WORDS: Vortex-assisted dispersive micro solid-phase extraction, Multiwalled carbon nanotubes, Cobalt, Nickel, Environmental samples, Flame atomic absorption spectrometry Bull. Chem. Soc. Ethiop. 2026, 40(1), 89-104. DOI: https://dx.doi.org/10.4314/bcse.v40i1.8