Microextraction Tech

Carbon nanoparticles and specifically carbon nanotubes can be considered as an inflection point in the development of microextraction techniques on account of their excellent sorbent properties. This fact permits the reduction of the dimensions of the extraction step while maintaining or even improving the preconcentration of the target compounds on the nanosorbent. Since then, different metallic and silica-based nanoparticles have been successfully evaluated in this context. In the last two-three years, a new nanosorbent has revolutionized again microextraction techniques. Graphene (G) and its oxide (GO) present a unique planar structure which makes them different from other nanoparticles and even from allotropic forms of carbon, which confers them with outstanding electrical, mechanical and structural properties. Carbon-based nanomaterials have been extensively used for the isolation and preconcentration of organic compounds usually of aromatic nature thanks to the possibility of re...

Every month, Analytical Methods journal publishes in its blog a list of hot articles that can be downloaded by free for a defined period of time. This is an interesting initiative that makes wider the impact of the journal providing free access to several articles. I usually read Analytical Methods blog for this reason (among others) and I strongly recommend it to our followers. In fact, this post is focused on one of the latest hot articles of this journal. Solid phase extraction is a consolidated sample preparation technique in any analytical laboratory. In spite of the wide variety of solids commercially available (e.g. silica-C18 and polymeric sorbents), the development of new ones capable of facing up the isolation and preconcentration of hydrophilic and ionic compounds would be desirable. For these compounds the performance of “conventional” sorbents is relatively low. Among the nanostructured solids, graphene and its derivative graphene oxide (GO) have been deeply stud...

Zinc oxide has been used as coating in solid phase microextraction (SPME) due to its good properties including thermal stability and affinity towards different analytes. In this sense, ZnO presents a high interaction with sulfur-containing molecules due to the strong coordination between Zn and S. However, this interaction is not completely exploited in SPME since pure ZnO coatings, prepared by sol-gel procedures, have a low surface area due to the enwrapping of ZnO nanoparticles (NPs) in the sol-gel network. In a recent article accepted for publication in Journal of Chromatography A, researchers from the Sun Ya-sen University at China have proposed a new approach to avoid this shortcoming. The proposal consists of the use of graphene as ZnO NPs support. The ZnO NPs are grown in the graphene (G) surface producing a composite which is final attached to a silica fiber by a sol-gel reaction in order to prepare the SPME coating. The whole synthetic procedure is described in detai...

Carbon-based nanomaterials have been extensively used as coatings in solid phase microextraction (SPME) due to their outstanding properties such as high thermal and mechanical stability, large superficial area and high affinity towards different compounds. Graphene (G), which was discovered in 2004, consists of one-atom-thick planar sheets of sp 2 -bonded carbon atoms that are densely packed in a honeycomb crystal lattice (see Figure). It can be considered the building block of some carbon allotropes like carbon nanotubes or graphite. In fact, in the usual synthetic procedure, graphene is obtained in the form of graphene oxide (GO) by chemical exfoliation of graphite. This GO can be finally reduced to G using reagents (like hydrazine or p -phenylene diamine) or a thermal treatment.