Determination of trace Bi by ICP-OES after magnetic solid phase extraction with fullerene C60 modified γ-Fe2O3 superparamagnetic iron oxide nanoparticles

In this research, a procedure for the preconcentration of Bi at trace levels in milk samples prior to inductively coupled plasma optical emission spectrometry (ICP-OES) is proposed. It is based on the batch magnetic solid phase extraction of Bi ions by fullerene C-60 modified maghemite (gamma-Fe2O3 superparamagnetic iron oxide nanoparticles - SPION) nanoparticles. The various factors that influence the preconcentration of Bi such as pH, the amount of magnetic nanoparticles, initial Bi concentration, sample volume and the effects of possible interfering ions were investigated. A linear analytical curve was achieved in the concentration range of 0.25-10 ng mL(-1) with a limit of detection of 0.06 ng mL(-1). The precision expressed as a RSD was 7.5% for a concentration of 0.25 ng mL(-1). The method was validated by the analysis of a standard reference material (NIST SRM 1643e). In addition, 96.6-98.7% recoveries were achieved for the spiked samples. Bi concentrations in ten milk samples were successfully determined after the developed method was applied. Bi content in the milk samples ranged from 6.5 to 14.3 ng mL(-1).