Modified magnetic nanoparticles with catechol as a selective sorbent for magnetic solid phase extraction of ultra-trace amounts of heavy metals in water and fruit samples followed by flow injection ICP-OES

A simultaneous and fast method was explored for extraction of heavy metal ions from aqueous samples based on magnetic solid phase extraction (MSPE). Fe3O4@catechol nanoparticles were successfully fabricated to coat catechol onto super paramagnetic iron oxide. Using a polymerization reaction the Fe3O4@catechol as a sorbent for MSPE method which was coupled with flow injection inductively coupled plasma optical emission spectrometry (FI-ICP-OES) was applied for the determination heavy metal in the water and fruit samples. The selectivity of synthesized sorbent for heavy metal ions is pH dependent. The heavy metal ions were selectively adsorbed on magnetic adsorbent, and then they were simply and rapidly isolated from sample solution with a strong magnet located in the bottom of the extraction vessel. After elution of heavy metal ions from surface of sorbent 250 μL of it was injected into the nebulizer of the FI-ICP-OES using the six-way two-position injection valve. The parameters influencing preconcentration factors of target ions, such as pH, extraction time, the sorbent amount, type of eluent, eluting solvent volume and desorption time were studied and optimized. Under the optimal conditions, the perconcentration factors in the range of 67-138 were obtained. The detection limits were as low as 0.2-0.9 μg L−1. The relative standard deviations (RSD) was lower than 6.6% (n = 6, C = 10.0 μg L−1). This new adsorbent was easily prepared with low-cost, utilized conveniently and was harmless to environment.