High accuracy and sensitivity test of work elements in environmental samples using surface modificated iron oxide magnetic nanoparticules

In this study, the In (II) and Au (III) ions, which are present in trace levels in natural sample environment, were determined by flaming AAS after enriching on iron oxide nanoparticles modified with oleic acid. It is aimed to develop a new solid phase extraction method to separate and pre-concentrate ions from the sample medium before analysis. In the SPE technique used for separation and enrichment processes; as solid phase support (adsorbent); Iron oxide magnetic nanoparticles whose surface was modified (expanded) with oleic acid were used. SPE method optimization in the enrichment process was carried out in the model solution environment. In order to determine optimum conditions, important analytical parameters such as pH, buffer amount, shaker type and duration, temperature and duration, eluent volume and matrix (interfer) effect were scanned and optimized. Under the most favorable conditions determined, analytical variables such as the observability limit (LOD) of the method, the limit of determination (LOQ) and the linear operating range were also determined. The accuracy of the method has been demonstrated using real samples (recovery) and standard reference materials. Metal determinations were performed using High Resolution Continuous Beam Source Flame Atomic Absorption Spectrometry (HR CSFAAS). Some optimum values for quantitative recovery of analyte ions are as follows; sample solution buffer amount was determined as 0.5 ml Au for In and 1.5 ml optimum buffer amount was determined. Magnetic nanoparticle (MNP) amount was determined as 50 mg for In and Au. Because after these optimum values, the amount of adsorbent increases and the retention values on the magnetic nanoparticle surface decrease. So adsorption is now negatively affected. In the pH experiments, the yield shifted to acidic regions more so that pH = 5 for In and pH = 3 for Au. Because at strongly acidic pH, hydrogen and metal ions competition occurs. In determining equilibrium contact times, the properties of the adsorbent used and the efficiency of the adsorbent to reach the maximum when the metal ion adsorbs are very important. In studies carried out for this, equilibrium contact time for both metals was found to be 40 s. For the effect of temperature, experiments were carried out at 5 different temperatures and it was determined that the retention of Au increased with temperature. It was observed that endothermic reactions took place and it was determined as the optimum value in yield for 60 ºC Au metal. In the interfer studies, 9 different metals were studied and the data were evaluated. The accuracy of the developed method has been checked by certified reference material analysis and application (recovery) studies to real samples. The developed method has been applied to the quantitative enrichment and determination of analytes in water samples. Thus, by using modified iron oxide magnetic nanoparticles, the adsorbent property for In and Au trace elements was determined. Keywords: Magnetic nanoparticles, micro extraction, atomic absorption spectrometry, indium, gold