Magnetic nanoparticles coated with non-ionic surfactants as restricted access material for solid phase extraction

By -

Restricted access materials (RAMs) are sorbents with enhanced selectivity due to their inherent structure since their extractive groups are protected by external functional groups that exclude macromolecules by a size exclusion and/or an electrostatic repulsion mechanism. Thus, only the small target analytes are able to reach the extracting phase avoiding the clogging of the sorbent by the sample matrix.

In a recent article accepted for publication in Journal of Chromatography A (1), researchers from Wuhan at China have proposed a new RAM based on the combination of magnetic nanoparticles and non-ionic surfactants. Magnetite nanoparticles (Fe304), which are synthesized by an oxidative-coprecipitation method, are the core of these RAMs providing them with a paramagnetic behavior which is essential for their easy isolation after the extraction process. The magnetite particles, with sizes in the low nm range, are subsequently derivatized with dodecyltriethoxisilane anchoring C12 extractive groups to their surface. Finally, a non-ionic surfactant is coated to the surface by a self-assembly process, producing a size-exclusion network that protects the extractive groups from the sample matrix components. In addition to the selectivity enhancement, the non-ionic surfactant coating improves the dispersibility of the RAM in the sample reducing the aggregation tendency of the hydrophobic particles in aqueous media.

In this article two series of non-ionic surfactants, Tween and Span series, were evaluated. Tween surfactants (TW-20, TW-40, TW-60 and TW-85) provide a better performance than Span surfactants (SP-40 SP-60 SP-80) due to their higher hydrophilic-lipophilic balance (HLB) which facilitates their dispersion in an aqueous media. The selectivity enhancement of the proposed RAM is evaluated in complex samples like urine where steroid hormones are determined with good sensitivity and precision levels.

These RAMs based on the combination of magnetic nanoparticles and non-ionic surfactants are quite promising according to their easy synthesis and their good extraction performance. In the article, the readers will find some additional and interesting information concerning the synthetic process as well as the different performance of the surfactants evaluated. Moreover, the optimization process clearly identified the effect of different experimental conditions.

References:
(1) Restricted-access nanoparticles for magnetic solid-phase extraction of steroid hormones from environmental and biological samples. Link

Related posts:
(I) Hydrophilic-carbonaceous magnetic nanoparticles coated with chitosan. Link

Comments

Post a Comment

Popular posts from this blog

Gold coated magnetic beads for electrochemical detection

By -
Image
This post summarizes an interesting article, recently accepted for publication in Analytical Chemistry, which presents an innovative use of magnetic beads. Researchers from the Osaka Prefecture University at Japan have proposed the synthesis of magnetic microbeads covered with a smooth gold layer that are used for the electrochemical detection of streptavidin (1). The synthesis, which is deeply described in the manuscript, consists of three well defined steps. First of all, the magnetic beads are introduced in a colloidal gold dispersion containing Au-nanoparticles (Au-NPs). Thanks to the opposite zeta potential of both materials (microbeads are negatively charged while Au-NPs present a positive charge), their assembly takes place by electrostatic interactions. However, the Au-NPs are not connected to each other and therefore the electrical resistance of the microbeads is too high. In a second step, the modified microbeads are dispersed in an aqueous medium containing HAuCl 4 as ...
Read more

Fabric phase sorptive extraction: a new generation green sample preparation strategy

By -
Image
by Dr. Abuzar Kabir, International Forensic Research Institute, Department of Chemistry and Biochemistry, Florida International University, Miami, Florida, USA Fabric phase sorptive extraction (FPSE), the most recent member of the sorptive microextraction family, has innovatively incorporated both solid phase microextraction (SPME) and solid phase extraction (SPE) techniques into a single technology platform. FPSE utilizes permeable natural/synthetic fabrics e.g., cotton, polyester, fiber glass supports to chemically bind sol-gel hybrid inorganic-inorganic sorbents. A 5 cm2unit of coated fabric (2.5 cm x 2.0 cm) is typically used as the extraction media which can be inserted directly into the sample container. Extraction of the analytes is generally expedited by using a magnetic stir bar to diffuse the analyts into the sample matrix so that rapid mass transfer from the sample matrix to the extraction medium takes place.Once the mass transfer equilibrium between the FPSE media and...
Read more

Rotating Disk Sorptive Extraction

By -
Image
by Prof. Dr. Pablo Richter, Department of Inorganic and Analytical Chemistry, Faculty of Chemical and Pharmaceutical Sciences, University of Chile. The modern trends in analytical chemistry promote efficiency and green technology in sample preparation. In this context, our research team developed a new technique in 2009 that is capable of extracting pollutants from liquid samples on a rotating PTFE disk with one surface coated with an extraction phase [1]. The disk has embedded a miniature magnetic rod, which allows rotation. We have termed this procedure rotating-disk sorptive extraction (RDSE). RDSE is currently available in two configurations. In the classic version (Figure 1), the extraction phase is a polymeric film adhered to one side of the PTFE disk (configuration 1). In this configuration, polydimethylsiloxane (PDMS), nylon and octadecyl (C18) have been used as the sorptive material for the extraction of low-polarity analytes (Log Kow between 3 and 7) [1-12]. However...
Read more