Development of a novel direct magnetic sorbent sampling device by flame furnace atomic absorption spectrometry (DMSS-FF-AAS) using a carbonaceous nanocomposite for highly sensitive determination of cadmium

Abstract

A novel and highly sensitive method for cadmium determination at ultratrace levels combining dispersive magnetic solid phase extraction (DMSPE), direct magnetic sorbent sampling (DMSS), and flame furnace atomic absorption spectrometry (FF-AAS) is described in this work. A magnetic carbon-based nanocomposite (Fe₃O₄@C) was used as the sorbent for cadmium preconcentration using DMSPE. The Fe₃O₄@C particles were easily separated from the aqueous medium by employing a magnetic stainless steel rod and directly inserting it inside a nickel tube heated by a flame. The method (DMSS-FF-AAS) showed substantially higher analytical performance when compared to FAAS, TS-FF-AAS (direct analysis), and TS-FF-AAS using preconcentration and elution steps, evidenced by a remarkable increase in the sensitivity of 2502, 151 and 41 times, respectively. Under the optimized conditions, the limit of detection, linearity, and the precision in terms of repeatability (n = 10) assessed as the relative standard deviation (RSD%) were found to be 5 ng L⁻¹, 15–750 ng L⁻¹, and 1–4%, respectively. The accuracy of the method was attested by analysis of certified reference materials, CRM-1643e (water) and CRM-1573a (tomato leaves). The proposed method was successfully applied for cadmium determination in mineral and lake water samples ranging from 16 to 465 ng L⁻¹.