Determination of cobalt and copper in water, plant, and soil samples by magnetite nanoparticle-based solid-phase microextraction (SPME) coupled with microsample injection system-flame atomic absorption spectrometry (MIS-FAAS)

Abstract

A magnetic solid-phase microextraction (SPME) procedure was optimized using Fe3O4 nanoparticles (NPs) to preconcentrate and determine cobalt and copper in real samples using microsample injection system-flame atomic absorption spectrometry (MIS-FAAS). Recoveries over 95% for Co(II) and 80% for Cu(II) from 90 mL of sample buffered to pH 4.0 were obtained using 50 mg Fe3O4 NPs as the adsorbent and 0.5 mL of 0.5 mol L-1 HNO3 as the eluent. The extraction time was 10 min. The preconcentration factors for Co(II) and Cu(II) were 180. The detection limits for Co(II) and Cu(II) were 1.2 and 0.9 mu g L-1, respectively. The relative uncertainties and relative standard deviations were lower than 5.3% and 2.4%, respectively. The developed method was verified by analyzing TMDW-500 drinking water, NIST 1573a Tomato leaves, and NCS DC 78302 Tibet soil as standard reference materials. The spiking experiments provided recoveries exceeding 95%. The method was applied to determine cobalt and copper in water, soil, tea infusion, and vegetable samples.