.jpg)
Graphene is widely idolized for its many properties and potential applications, and rightly so. One lesser known application is in microextraction methods. There are many extraction methods out there, but one recently developed method, known as matrix solid-phase dispersion microextraction (MSPDM) has gathered a lot of attention.
A team of Researchers from China have now used graphene nanoplatelets to develop a simple and environmentally friendly MSPDM method coupled with ultrahigh performance liquid chromatography and electrochemical detection (UHPLC-ECD) for the simultaneous extraction and identification of phenolic acids.
Microextraction methods have arose from the natural evolution and progression of pre-treatment processes which aim for a simplistic miniaturization for the extraction of inorganic and organic analytes. These have been traditionally classed under two main categories: liquid-phase microextraction (LPME) and solid-phase microextraction (SPME).
Compared to traditional extraction methods, microextraction methods have shown to be advantageous for their lower consumption of solvent and sample, generation of less waste, high enrichment factors and lower extraction times.
Recently, a new microextraction method has been utilized by Scientists, and is known as matrix solid-phase dispersion microextraction (MSPDM) and is a variation on old matrix solid-phase dispersion (MSPD) extraction methods.
The team of Researchers have now investigated this method further by utilizing graphene nanoplatelets (GNPs) alongside ultrahigh performance liquid chromatography and electrochemical detection (UHPLC-ECD) to simultaneously extract and identify six phenolic compounds in Danshen (plant extract) tablets. The six phenolic compounds analyzed were sodium danshensu, rosmarinic acid, salvianolic acid A, salvianolic acid B, protocatechuic aldehyde and lithospermic acid.
In this setup, the GNPs were used as the sorbent material, whilst water acted as the elution solvent. Before deciding upon this setup, various graphene derivatives and solvent (both aqueous and organic) were tested in varying ratios.
The various graphene derivatives were tested for this application as its ultrahigh specific area and π-π electrostatic stacking properties allow it to efficiently absorb compounds which contain phenol (benzene) rings. Graphene is also very sensitive to changes in the environment allowing for an easy detection and quantification once compounds have attached to it.
During their experiments, the Researchers carried out their analyzes using an Agilent 1290 system equipped with an Antec SDC ECD. The Researchers also utilized scanning electron microscopy (SEM, HT7700, Hitachi) and transmission electron microscopy (TEM, Supra55 microscope, Zeiss), Fourier transform infrared spectroscopy (FT-IR, Nicolet iS5, Thermo Scientific) and atomic force microscopy (AFM, Ver551B) with NSC15/AIBS silicon cantilevers (μmash, NanoNavi) to characterize the morphologies and microstructures of the GNPs and Danshen tablets.
The new graphene-based microextraction method was successful in simultaneously extracting and identifying the six phenolic compounds, and the Researchers investigated the parameter that affected the extraction performance of these compounds, and subsequently optimised them.
Alongside determining that GNPs and water were the best sorbents and solvents, respectively, the Researchers also determined that a 1:1 ratio of the two was optimal. The pre-treatment process was also optimized, and a grinding time of the GNP sorbent material (to create a homogeneous mixture) of 60 seconds with 0.2 mL of the water elution solvent.
Under the optimal conditions, the Researchers found that the micro extraction process possessed a good repeatability and linearity (r2≥0.9991) over many runs. This was found to be alongside an excellent precision (RSD≤4.57%) and satisfactory recoveries between 82.34% and 98.34%.
The limit of detection (LOD) for the method was found to range between 1.19 and 4.62 ng/mL across the six phenolic acids, with sodium danshensu possessing the greatest LOD and Rosmarinic acid possessing the worst. However, Rosmarinic acid was shown to possess the highest repeatability (r2=0.9996), whilst sodium danshensu and lithospermic acid showed the lowest at 0.9991.
When compared with other extraction and microextraction methods, this approach was found to use less sample (and required less sample to run), use less solvent and possessed a quicker extraction time. Such improvements will lend itself to replacing other microextraction methods in the future, especially those which are specifically used on phenolic compounds.
Image Credit:
Artbox/ Shutterstock.com
Source:
“Graphene nanoplatelets based matrix solid-phase dispersion microextraction for phenolic acids by ultrahigh performance liquid chromatography with electrochemical detection”- Peng L-Q., et al, Scientific Reports, 2017, DOI:10.1038/s41598-017-07840-2
Disclaimer: The views expressed here are those of the author expressed in their private capacity and do not necessarily represent the views of AZoM.com Limited T/A AZoNetwork the owner and operator of this website. This disclaimer forms part of the Terms and conditions of use of this website.