Simultaneous electrochemical detection of multiple heavy metal ions in milk based on silica-modified magnetic nanoparticles.

A sensitive and simple analytical method integrated with Fe3O4@SiO2-based extraction with direct electrochemical detection was applied to individually and simultaneously analyze heavy metal ions, including Cd2+, Pb2+, Cu2+, and Hg2+. The Fe3O4@SiO2-based electrochemical sensor was developed through the mixture of heavy metal ions with Fe3O4@SiO2 after alkali treatment, which was modified onto the working electrode surface. The Fe3O4@SiO2 with negative charges after alkali treatment could easily interact with heavy metal ions with positive charges by electrostatic force. Under the optimized conditions, the developed analytical method could be applied to individually and simultaneously detect heavy metal ions with good sensitivity. The detection limits were all in the nanomolar range, and the recoveries ranged from 96.0 to 104.3% for heavy metal ions in milk. Therefore, the proposed analytical method exhibited great potential for quantitatively analyzing multiple heavy metal ions in milk.

Electrochemical detection of aminoglycoside antibiotics residuals in milk based on magnetic molecularly imprinted particles and metal ions.

This work proposed a cost-effective, simple, and highly sensitive magnetic molecularly imprinted particles (MMIPs) electrochemical sensor to indirectly detect kanamycin (KAN), tobramycin (TOB), and gentamicin (GEN). The MMIPs electrochemical sensor was prepared by a complex of metal ions and the MMIPs of rebinding the template, which modified on the magnetic glassy carbon electrode surface. Here, metal ions were used as the signal tracers and amplifiers of the MMIPs electrochemical sensor. Then the response peak currents of metal re-oxidized to metal ion was recorded by differential pulse voltammetry and used to monitor the level of aminoglycoside antibiotics. Under the optimal conditions, the MMIPs electrochemical sensors showed a high sensitivity toward KAN, TOB, and GEN with detection limits of 4.88, 1.28, and 1.07 nmol/L, respectively. Furthermore, the MMIPs electrochemical sensors showed high selectivity for determining KAN, TOB, and GEN, and they were successfully used to detect KAN, TOB, and GEN in milk.