Search

Conventional monitoring of metal ions in edible vegetable oils is crucial for assessing the quality and safety of consumers. In the current study, we developed a magnetic effervescence–enhanced emulsification microextraction (MEEM-DM) based on the employment of effervescent tablets composed of dicationic ionic liquids (DILs), MFe2O4 nanoparticles, and acidic and alkaline sources. The MEEM-DM pre-treatment was combined with inductively coupled plasma mass spectrometry (ICP-MS) analysis for trace-level detection of Cr(VI) and Cu(II) in ten types of edible oil. It realized efficient preconcentration/extraction by DILs, vigorous dispersion by effervescent reaction, and rapid separation/collection by MFe2O4 in one synchronous step. As the DIL ([Cn(MIM)2]Br2) possesses two active centers, it provided superior adsorption/extraction performance for metal ions when compared with its corresponding monocationic form ([Cn(MIM)]Br). Four types of MFe2O4 were synthesized and characterized, in which NiFe2O4 nanoparticles presented a larger specific surface area and smaller particle diameter than others. The optimized parameters for ICP-MS were as follows: flow rate of carrier gas, 1.15 L/min, and ICP ratio frequency power, 1550 W. The optimized MEEM-DM conditions were as follows: 0.46 g Na2CO3, 60 mg [C4(MIM)2]Br2, 45 mg Na[N(CN)2], 10 mg NiFe2O4, 0.58 g for each tablet, and 0.50 M HCl solution. The newly developed method gave satisfactory detection limits (0.076–0.086 μg/kg) and recoveries (96.9–105.8%) for Cr(VI) and Cu(II) that were comparable with conventional ultrasound-assisted extraction and microwave-assisted acid-digestion methods. These superior performance metrics show an additive extraction action between DILs and MFe2O4 in an effervescent reaction–enhanced microextraction and great potential in the conventional monitoring of heavy metals in edible oil samples. [ABSTRACT FROM AUTHOR]

The performance and the characteristics of various sensors are analyzed to meet the requirement of measuring the bone force-electromechanical potentials. The strain sensor that is suitable small signal and bone force-electromechanical potential measure is developed and the curved structural form of the strain sensor is chosen. The strain sensor has the advantage of small volume, large linear range, convenient installation and high sensitivity. The relationship between the strain and force-electromechanical potential of bone specimen is determined in the experiment on the bone of femur and bone of teeth using this type of sensor which provides the valuable data for clinical use.