Development of an effervescent tablet microextraction method using NiFe2O4-based magnetic nanoparticles for preconcentration/extraction of heavy metals prior to ICP-MS analysis of seafood

Abstract

Herein, we synthesized and characterized NiFe₂O₄-based magnetic nanoparticles (MNPs) and used these MNPs in an effervescent tablet-assisted dispersive solid-phase microextraction (MNET-DSPM) method for preconcentration/extraction of trace Cu, Mn, Zn and Cd ions prior to inductively coupled plasma mass spectrometry (ICP-MS) detection of seafood. A 0.2 g magnetic effervescent tablet (8 mm diameter × 2 mm thickness) consisted of Na₂CO₃, NaH₂PO₄ and NiFe₂O₄ MNPs. In the MNET-DSPM method, NiFe₂O₄ was used as both the adsorbent and the magnetic separation agent with the aid of CO₂ released by reaction of an acid source and a base source. This is done so as to avoid utilization of additional energy sources and chelating agents. Moreover, this newly developed method has many advantages such as having no need for complex devices or instrumentation, easy operation in a magnetic field, high sensitivity/accuracy and short extraction time by the dispersion of effervescent tablets and adsorption of MNPs. Several important parameters were optimized using the one-factor-at-a-time approach. Under the optimized conditions, the MNET-DSPM/ICP-MS method gave LODs for the four metal ions as low as 0.007–0.018 μg kg⁻¹, extraction recoveries of 73.4–99.3%, and high precisions with intra- and inter-day RSDs of 1.5–6.1%. Cu, Mn and Zn ions in shrimp, squid, shellfish and little yellow croaker samples were detected to be in the range of 1.92–173.53 μg kg⁻¹. To our knowledge, this is the first time that a NiFe₂O₄-based effervescent microextraction for detection of metal ions in seafood is developed. Based on a series of superior analytical performances, this MNET-DSPM/ICP-MS method will have a great potential application value in routine pollution monitoring of seafood.