One-step effervescent tablet-assisted dispersive solid-phase microextraction based on an l-cysteine-functionalized carbon-coated magnetic nanocomposite for the determination of iron and zinc ions in milk samples

Abstract

In this study, a L-cysteine-functionalized carbon-coated magnetic nanocomposite (CoFe₂O₄/C@Cys) was effectively synthesized and employed as an adsorbent in effervescent tablet-assisted dispersive solid-phase microextraction (ET-DSPM) for enrichment of heavy metals (Fe(III) and Zn(II)). The as-prepared composites were extensively characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and vibrating sample magnetometer (VSM) techniques. The influence of various factors on the extraction efficiency of heavy metals was methodically examined in this study. After quickly transferring the effervescence tablet into the aqueous sample, the effervescent agent (sodium dihydrogen phosphate and sodium carbonate) simultaneously reacted and produced carbon dioxide (CO₂). The in situ produced CO₂ facilitated the dispersion of nanoparticles in the aqueous sample and significantly enhanced the extraction efficiency. Under the optimal parameters, the results showed that the CoFe₂O₄/C@Cys-ET-DSPM method displayed superior analytical performance for quantification of two heavy metals in milk samples with a preconcentration factor of 20, limits of detection (LODs) of 0.10–0.12 μg kg⁻¹, recoveries of 77.1–101.7% and RSDs of 1.1–7.0%, respectively. The one-step extraction approach combined with an atomic absorption spectrometer exhibits promising potential for application in field analysis.