Hydrolytic enzyme modified magnetic nanoparticles: An innovative and green microextraction system for inorganic...

In the presented study, the usability of hydrolytic enzyme immobilized magnetic nanoparticles as an extraction agent for the microextraction of metal ions from food samples was investigated. α-amylase modified magnetic carbon nanotubes (α-amylase-Fe₃O₄/MWCNTs) was used as an extraction agent for direct microextraction of trace arsenic from food sample phase into liquid phase medium prior to its ICP-MS determination. In extraction studies using hydrolytic enzymes, it is impossible to recover the free soluble enzyme after extraction without losing its activity. In our study, this problem was overcome by immobilizing the hydrolytic enzyme on magnetic support. In this way, α-amylase-Fe₃O₄/MWCNTs as an extraction agent with a reuse property of at least six times was used. α-amylase-Fe₃O₄/MWCNTs was characterized by FT-IR, XRD, SEM, SEM-EDX, VSM, TGA, and DTG techniques. Optimization of the presented method was performed using 1568 A rice flour certified reference material. Analytical parameters such as type of hydrolytic enzyme, pH and volume of the aqueous phase, extraction temperature and ultrasonic irridation time were optimized. The microextraction step was performed in ultrasonic water bath within only ∼15 min. Limit of detection (LOD), limit of quantification (LOQ) and relative standard deviation (RSD %) values for the developed method were found to be 14.3 μg kg^-1, 47.3 μg kg^-1 and 7.5%, respectively. The method was successfully applied to the analysis of arsenic contents of different rice and flour samples.