Magnetic solid-phase extraction based on multi-walled carbon nanotubes combined ferroferric oxide nanoparticles for the determination of five heavy metal ions in water samples by inductively coupled plasma mass spectrometry.

An excellent magnetic multi-walled carbon nanotubes (MMWCNT) containing carboxyl material modified with ferroferric oxide (FeO) nanoparticles was synthesized as the adsorbent for magnetic solid-phase extraction (MSPE) of five heavy metal ions (Pb, Cu, Co, Cd, Cr) in water samples followed by on-line inductively coupled plasma mass spectrometry (ICP-MS) detection. The characteristics of the adsorbent were analyzed using Fourier transform infrared spectroscopy (FT-IR), scanning electron microscope (SEM), and vibrating sample magnetometer (VSM). Some factors affecting extraction efficiency including pH of sample solution, the amount of adsorbent, extraction method and time, concentration and volume of desorption solvent, desorption time and evaluation of coexisting ions were optimized.

Analysis of six preservatives in beverages using hydrophilic deep eutectic solvent as disperser in dispersive liquid-liquid microextraction based on the solidification of floating organic droplet.

In this work, a deep eutectic solvent (DES) composed of tetrabutylammonium bromide (TBABr) and acetic acid in a 1:2 M ratio was applied as the dispersive solvent for the dispersive liquid-liquid microextraction based on solidification of floating organic droplet (DLLME-SFO), using 1-decanol as extractant. Six preservatives (benzoic acid, BA; sorbic acid, SA; methyl paraben, MP; ethyl paraben, EP; propyl paraben PP; and butyl paraben, BP) in beverages were determined simultaneously through high-performance liquid chromatography with a diode array detector (HPLC-DAD). Under the optimal experimental condition that consists of 200 μL of disperser (TBABr: acetic acid, 1:2), 80 μL of extractant (1-decanol), 3 min of vortex time, 4.