Graphene composite for the extraction of hydrophilic compounds

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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 studied in the extraction context due to their exceptional properties in terms of surface area and high π-electron density. In contrast to other carbonaceous nanomaterials, GO present a relatively high solubility in water which clearly minimizes the bundle formation. It is rather relevant as it maximizes the active groups available for the interaction with the analytes.

Taking advantage of these characteristics, Analytical Methods has published a research article devoted to the synthesis, characterization and practical application of a double carboxyl silicane modified graphene oxide coated silica composite (1) for the isolation of quaternary alkaloids (highly hydrophilic and charged compounds). The key aspect of the novel sorbent is the presence in the composite of 3-(trietoxy silicon) propyl succinic anhydride (TSPA) which can present two carbonyl groups after an hydrolysis step. The anchorage of this reagent on the GO surface enhances the hydrophilicty of the sorbent and also confers ion-exchange character with a synergic effect on dipole-dipole interactions. In order to maximize the sorption, the authors immobilized the hybrid nanosorbent into silica particles.

The preparation of the sorbent is clearly described in the article and also the characterization studies have been included. It should be noted that the breakthrough volume is as high as 70 mL which is a favorable feature in terms of enrichment factors as quantitative elution is achieved using 1 mL of methanol.

We encourage our followers to go through the full article for more specific information

References
(1) Double carboxyl silicane modified graphene oxide coated silica composite as sorbent for solid-phase extraction of quarternary alkaloids. Link to the article


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