Magnetic Dispersive Solid-phase Extraction Research Articles

Fast determination of seven synthetic pigments from wine and soft drinks using magnetic dispersive solid-phase extraction followed by liquid chromatography–tandem mass spectrometry

A novel, simple and sensitive method based on the use of magnetic dispersive solid-phase extraction (M-dSPE) procedure combined with ultra-fast liquid chromatography-tandem quadrupole mass spectrometry (UFLC–MS/MS) was developed to determine seven synthetic pigments (tartrazine, amaranth, carmine, sunset yellow, allura red, brilliant blue and erythrosine) in wines and soft drinks. An amino-functionalized low degrees of cross-linking magnetic polymer (NH2-LDC-MP) was synthesized via suspension polymerization, and characterized by transmission electron microscopy (TEM). The NH2-LDC-MP was used as the M-dSPE sorbent to remove the matrix from the solution, and the main factors affecting the extraction were investigated in detail. The obtained results demonstrated the higher extraction capacity of NH2-LDC-MP with recoveries between 84.0 and 116.2%. The limits of quantification (LOQs) for the seven synthetic pigments were between 1.51 and 5.0μg/L in wines and soft drinks. The developed M-dSPE UFLC–MS/MS method had been successfully applied to the real wines and soft drinks for food-safety risk monitoring in Zhejiang Province, China. The results showed that sunset yellow was in three out of thirty soft drink samples (2.95–42.6μg/L), and erythrosine in one out of fifteen dry red wine samples (3.22μg/L), respectively. It was confirmed that the NH2-LDC-MP was a kind of highly effective M-dSPE materials for the pigments analyses.

Ionic liquid-modified magnetic polymeric microspheres as dispersive solid phase extraction adsorbent: a separation strategy applied to the screening of sulfamonomethoxine and sulfachloropyrazine from urine

Ionic liquid-modified magnetic polymeric microspheres (ILMPM) were prepared based on Fe3O4 magnetic nanoparticles (MNPs) and ionic liquids (ILs) incorporated into a polymer. The composites were characterized using scanning electron microscopy, Fourier transform infrared analysis, thermogravimetric analysis, X-ray diffraction, and vibrating magnetometer, which indicated that ILMPM had a regularly spherical shape and strong magnetic property. The obtained ILMPM were successfully applied as a special adsorbent of magnetic dispersive solid phase extraction (MDSPE) for the rapid extraction and isolation of sulfamonomethoxine sodium and sulfachloropyrazine sodium in urine. The factors that affected extraction efficiency, such as adsorption conditions, desorption conditions, washing and elution solvents, and pH of the sample solution, were optimized. Under the optimum condition, good linearity in the range of 0.005-2.0 μg g(-1) (r ≥ 0.9996) was obtained for the two sulfonamides (SAs); the average recoveries at three spiked levels ranged from 86.9 to 102.1 %, with relative standard deviations of ≤4.3 %. The presented ILMPM-MDSPE method combined the advantages of ILs, MNPs, and MDSPE and therefore could be potentially applied for rapid screening of SAs in urine.

Simultaneous in situ derivatization and ultrasound-assisted dispersive magnetic solid phase extraction for thiamine determination by spectrofluorimetry.

A simple and rapid method for the simultaneous in situ derivatizaion, preconcentration and extraction of thiamine (vitamin B1) as a model analyte was developed by a novel quantitative method, namely ultrasound-assisted dispersive magnetic solid phase extraction spectrofluorimetry (USA-DMSPE-FL) from different real samples. This method consists of sample preparation, in situ derivatization, exhaustive extraction and clean up by a single process. High extraction efficiency and in situ derivatization in a short period of time is the main advantages of this procedure. For this purpose, the reusable magnetic multi-wall carbon nanotube (MMWCNT) nanocomposite was used as an adsorbent for preconcentration and determination of thiamine. Thiamine was, simultaneously, in situ derivatized as thiochrome by potassium hexacyanoferrate (III) and adsorbed on MMWCNT in an ultrasonic water bath. The MMWCNTs were then collected using an external magnetic field. Subsequently, the extracted thiochrome was washed from the surface of the adsorbent and determined by spectrofluorimetry. The developed method, which has been analytically characterized under its optimal operating conditions, allows the detection of the analyte in the samples with method detection limits of 0.37 µg L(-1). The repeatability of the method, expressed as the relative standard deviation (RSD, n=6), varies between 2.0% and 4.8% in different real samples, while the enhancement factor is 197. The proposed procedure has been applied for the determination of thiamine in biological (serum and urine), pharmaceutical (multivitamin tablet and B complex syrup) and foodstuff samples (cereal, wheat flour, banana and honey) with the good recoveries in the range from 90% to 105%.

Extraction and derivatization of chemical weapons convention relevant aminoalcohols on magnetic cation-exchange resins

Analysis and identification of nitrogen containing aminoalcohols is an integral part of the verification analysis of chemical weapons convention (CWC). This study was aimed to develop extraction and derivatization of aminoalcohols of CWC relevance by using magnetic dispersive solid-phase extraction (MDSPE) in combination with on-resin derivatization (ORD). For this purpose, sulfonated magnetic cation-exchange resins (SMRs) were prepared using magnetite nanoparticles as core, styrene and divinylbenzene as polymer coat and sulfonic acid as acidic cation exchanger. SMRs were successfully employed as extractant for targeted basic analytes. Adsorbed analytes were derivatized with hexamethyldisilazane (HMDS) on the surface of extractant. Derivatized (silylated) compounds were analyzed by GC–MS in SIM and full scan mode. The linearity of the method ranged from 5 to 200ngmL−1. The LOD and LOQ ranged from 2 to 6ngmL−1 and 5 to 19ngmL−1 respectively. The relative standard deviation for intra-day repeatability and inter-day intermediate precision ranged from 5.1% to 6.6% and 0.2% to 7.6% respectively. Recoveries of analytes from spiked water samples from different sources varied from 28.4% to 89.3%.

Dispersive magnetic solid phase extraction based on an ionic liquid ferrofluid

A novel, fast and efficient ionic liquid-based dispersive magnetic solid phase extraction (IL-D-SPE) method was developed and applied for preconcentration of Cd(ii) (as a model analyte) from aqueous solutions as a prior step to its determination by flame atomic absorption spectrometry (FAAS).

Magnetic molecularly imprinted nanoparticles based on dendritic-grafting modification for determination of estrogens in plasma samples

In order to resolve the low imprinting efficiency of surface molecularly imprinted polymers (MIPs), a dendritic-grafting method introducing more functional groups was proposed to modify the SiO2-coated magnetic nanoparticles (SiO2-coated MNPs). And then magnetic MIPs (MMIPs) were obtained using 17-ethyl estradiol (EE2) as a pseudo template with dendronized SiO2-coated MNPs as the supporter, aiming to avoid residual template leakage and to increase the imprinting efficiency. The resulting MMIPs showed high adsorption capacity, quick binding kinetics and good selectivity for trace estrogens. Meanwhile, MMIPs were used as magnetic dispersive solid-phase extraction (MDSPE) materials coupled with HPLC-UV for the detection of trace estrogens. The amounts of three estrogens which were detected from the plasma samples of pregnant women were 5.28, 5.31 and 4.17ngmL−1, and the average recoveries were 87.8%, 93.1% and 90.6% for the spiked samples with RSDs in the range of 1.4–6.3%, respectively. All these results reveal that MMIPs as MDSPE materials has good applicability to selective extraction and separation of trace estrogens from complex samples.