Agarose Based Magnetic Solid-Phase Extraction-Magnetic Field Agitation for Determination of Trace Amounts of Molybdenum in Beans

A magnetic solid-phase extraction method based on agarose coated magnetic nanoparticles (ACMNPs) coupled to a magnetic field agitation (MFA) device was developed and used for the preconcentration and graphite furnace atomic absorption spectrometric determination of trace amounts of MoVI in beans. The formation of the nanoparticles and their encapsulation in agarose micro-flakes was conducted in a single step. The nanomagnetic agarose particles were activated by an epichlorohydrin method, functionalized by phenylephrine and used for selective preconcentration of MoVI. The influence of different analytical parameters such as pH, extraction time, type and volume of eluent and amount of adsorbent on the preconcentration of MoVI were investigated. No important interferences were observed for the determination of the analyte in presence of several other metal ions. The capacity of the adsorbent for MoVI at pH 4.0, was 13.2 µg per mL of its packed volume. Eight replicated analyses at the optimized conditions resulted in a recovery of 95.3% with a relative standard deviation of 4.9%. The detection limit of the method (3σ) for MoVI was 49 ng L-1. The method was successfully applied to the determination of MoVI in beans samples.