Marine ecosystems cover more than 70% of the globe's surface. These habitats are occupied by a great diversity of marine organisms that produce highly structural diverse metabolites as a defense ...mechanism. In the last decades, these metabolites have been extracted and isolated in order to test them in different bioassays and assess their potential to fight human diseases. Since traditional extraction techniques are both solvent- and time-consuming, this review emphasizes alternative extraction techniques, such as supercritical fluid extraction, pressurized solvent extraction, microwave-assisted extraction, ultrasound-assisted extraction, pulsed electric field-assisted extraction, enzyme-assisted extraction, and extraction with switchable solvents and ionic liquids, applied in the search for marine compounds. Only studies published in the 21st century are considered.
•Fundamentals of extraction and clean-up methods are given.•Application of extraction and clean-up methods for different alkaloids is provided.•Factors that influence each technique are ...discussed.•Advantages and limitations of each technique are addressed.
Alkaloids are a chemically diverse group of natural products known for their pharmacological and toxicological effects. Plants are the best known source of these compounds. Because of their high complexity, herbal matrices must be properly processed in order to access alkaloid content, overcoming different analytical steps, such as sampling, sample preparation, isolation, quantification and data analysis. Notably, sample preparation just recently is calling the attention, being considered a bottleneck of analytical processes. In this review, we provide the current state of the art in sample preparation for alkaloids analysis in herbal matrices, focusing on both extraction and clean-up steps. Both classic and modern techniques, such as Negative-Pressure Cavitation Extraction (NPCE), Microwave Assisted Extraction (MAE), as well as microfluidic chips are addressed, including the technique fundamentals, factors to be optimized, and their applications. A general discussion is also given, pointing out the advantages and limitations of each technique.
Extraction of phenolic compounds: A review Alara, Oluwaseun Ruth; Abdurahman, Nour Hamid; Ukaegbu, Chinonso Ishamel
Current research in food science,
01/2021, Volume:
4
Journal Article
Peer reviewed
Open access
Phenolic compounds are parts of secondary metabolites mostly found in plant species with enormous structural diversities. They can exist as glycosides or aglycones; matrix or free-bound compounds; ...and comprising mostly polymerized or monomer structures. Additionally, these compounds are not universally dispensed within plants with varied stability. This has contributed to challenging extraction processes; implying that employing a single step or inappropriate extraction technique might change the recovery of phenolic components from the plant samples. Hence, it is important to select an appropriate extraction method so as to recover the targeted phenolic compounds. This is will helps to recover substantial yields from the sample matrix. Therefore, this review mainly focuses on the phenolic compounds and several methods of extraction that are used to obtaining them from plant materials. These extraction methods includes both conventional and unconventional techniques.
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•Phenolic compounds from natural sources.•Methods of extracting phenolic compounds.•Selection of an appropriate extraction method to recover the targeted phenolic compounds from plant materials.
Pressurized liquid extraction (PLE) is a tool able to provide green extraction methods to further determine contaminants in food and the environment. The aim of this review is to offer a critical ...overview of the recent developments within this field and can be considered as an update of the previous that we published in 2015. Trends regarding sample treatment, solvents, in-cell clean-up approaches used in the extraction of organic contaminants are addressed. Special attention deserve those methods that include on-line clean up in the extraction cell. Comparison with other green techniques is also presented. The final objective of this review is to clearly define the role that this technique plays in the analysis of organic pollutants, their strengths and weaknesses, as well as the updated spectrum of applications for which PLE is an essential tool.
•Update review of the PLE to extract contaminants in food and the environment.•Establishment of the applications for which PLE is advantageous.•Main analytical parameters of the different PLE procedures are discussed.•Advantages and limitations in the analysis are considered and evaluated.•Future trends and prospects are envisaged.
Electromembrane extraction Huang, Chuixiu; Chen, Zhiliang; Gjelstad, Astrid ...
TrAC, Trends in analytical chemistry (Regular ed.),
October 2017, 2017-10-00, Volume:
95
Journal Article
Peer reviewed
Electromembrane extraction (EME) was inspired by solid-phase microextraction and developed from hollow fiber liquid-phase microextraction in 2006 by applying an electric field over the supported ...liquid membrane (SLM). EME provides rapid extraction, efficient sample clean-up and selectivity based on the nature of the SLM and the electrical field. EME has been applied for the separation of ionizable compounds from complex samples, and EME is currently considered as an active research topic in the area of sample preparation and analytical chemistry. We expect that EME will play important roles in future analytical laboratories. This review summarizes and highlights the advancements in EME from 2006 to 2016 with focuses on 1) fundamental aspects, 2) device and operation modes, 3) performance, and 4) hyphenation to other analytical sample preparation techniques. Meanwhile, this review indicates that the main objectives for future EME are to establish EME as tool for routine applications, and to stimulate for further research on sophisticated systems based on the EME principle.
Electromembrane extraction (EME) is a microextraction technique intended for extraction of cations and anions by applying an electric field over the supported liquid membrane (SLM). Display omitted
•Advances on the device and operation modes in electromembrane extraction are emphasized.•Selective, exhaustive and soft extractions using electromembrane extraction are summarized.•Hyphenation of electromembrane extraction to other sample preparation technique is reviewed.•Electrolysis, stability, and mass transfer in electromembrane extraction are discussed.•The main objectives for future electromembrane extraction are identified.
Template removal is a critical step in the preparation of most molecularly imprinted polymers (MIPs). The polymer network itself and the affinity of the imprinted cavities for the template make its ...removal hard. If there are remaining template molecules in the MIPs, less cavities will be available for rebinding, which decreases efficiency. Furthermore, if template bleeding occurs during analytical applications, errors will arise. Despite the relevance to the MIPs performance, template removal has received scarce attention and is currently the least cost-effective step of the MIP development. Attempts to reach complete template removal may involve the use of too drastic conditions in conventional extraction techniques, resulting in the damage or the collapse of the imprinted cavities. Advances in the extraction techniques in the last decade may provide optimized tools. The aim of this review is to analyze the available data on the efficiency of diverse extraction techniques for template removal, paying attention not only to the removal yield but also to MIPs performance. Such an analysis is expected to be useful for opening a way to rational approaches for template removal (minimizing the costs of solvents and time) instead of the current trial-and-error methods.
The extraction of nucleic acids (NA) is an essential component of NA analysis. Without sufficient extraction and purification, contaminants co-existing with NAs often inhibit enzymatic amplification ...causing poor reproducibility and sensitivity. Numerous advancements in NA sampling in recent years have led to improvements in extraction yields from complex matrices and the reduction of analysis times. Perhaps most notable is the push towards miniaturization and automation to facilitate point-of-care testing. This article reviews the advancements and current trends in NA sample preparation including cell lysis and NA extraction.
•Advancements in nucleic acid (NA) sample preparation, including cell lysis and purification, are discussed.•New extraction solvents in liquid-liquid extraction offer unique advantages over traditional methods.•The large surface area and ease of modification make magnetic nanoparticles attractive in NA analysis.•Microfluidic devices allow multiple sample preparation steps to be integrated for point-of-care testing.•Sequence-specific NA enrichment techniques enable quantification of low abundance sequences.
•A novel adaptive signal decomposition method named RVME is proposed.•Simulated and experimental cases validate the effectiveness of the proposed method.•RVME has higher computational efficiency than ...VMD.
The variational mode extraction (VME) developed on the similar basis of variational mode decomposition (VMD) can effectively separate a specific mode by knowing an approximate center frequency from the multi-component signal. Compared with VMD, VME has made certain progress in improving the extraction accuracy and reducing the computational cost when the aim is to separate a specific mode. As the fault feature signal of rolling bearing is usually a band-limited signal which is compact around the excited resonant frequency, VME becomes a potentially effective tool for extracting fault characteristics of rolling bearing. However, how to adaptivelydetermine the center frequency and the penalty factor are two difficult problems when using VME to separate the desired component. Accordingly, this paper presents the recursive variational mode extraction (RVME), an iterative VME-based signal decomposition algorithm. At each iteration of RVME, the initial center frequency and penalty factor for the reconstruction of a specific sub-component can be adaptively determined according to the dominant frequency of the residual signal of the previous iterative decomposition, which makes RVME an adaptive signal decomposition algorithm. The presented method is applied to simulated and experimental fault signals and compared with other classical fault feature extraction approaches, such as variational mode decomposition (VMD) and spectral kurtosis (SK). The results confirm that the established method can extract the fault features as effective as VMD, but it is significantly better than VMD in terms of computational efficiency. Meanwhile, the proposed method shows a stronger capability of weak bearing fault feature extraction and compound fault feature separation compared with SK.
Naturally active compounds are usually contained inside plants and materials thereof. Thus, the extraction of the active compounds from plants needs appropriate extraction methods. The commonly ...employed extraction methods are mostly based on solid-liquid extraction. Frequently used conventional extraction methods such as maceration, heat-assisted extraction, Soxhlet extraction, and hydrodistillation are often criticized for large solvent consumption and long extraction times. Therefore, many advanced extraction methods incorporating various technologies such as ultrasound, microwaves, high pressure, high voltage, enzyme hydrolysis, innovative solvent systems, adsorption, and mechanical forces have been studied. These advanced extraction methods are often better than conventional methods in terms of higher yields, higher selectivity, lower solvent consumption, shorter processing time, better energy efficiency, and potential to avoid organic solvents. They are usually designed to be greener, more sustainable, and environment friendly. In this review, we have critically described recently developed extraction methods pertaining to obtaining active compounds from plants and materials thereof. Main factors that affect the extraction performances are tuned, and extraction methods are chosen in line with the properties of targeted active compounds or the objectives of extraction. The review also highlights the advancements in extraction procedures by using combinations of extraction methods to obtain high overall yields or high purity extracts.
An interest in the development of extraction techniques of biomolecules from various natural sources has increased in recent years due to their potential applications particularly for food and ...nutraceutical purposes. The presence of polysaccharides such as hemicelluloses, starch, pectin inside the cell wall, reduces the extraction efficiency of conventional extraction techniques. Conventional techniques also suffer from low extraction yields, time inefficiency and inferior extract quality due to traces of organic solvents present in them. Hence, there is a need of the green and novel extraction methods to recover biomolecules. The present review provides a holistic insight to various aspects related to enzyme aided extraction. Applications of enzymes in the recovery of various biomolecules such as polyphenols, oils, polysaccharides, flavours and colorants have been highlighted. Additionally, the employment of hyphenated extraction technologies can overcome some of the major drawbacks of enzyme based extraction such as longer extraction time and immoderate use of solvents. This review also includes hyphenated intensification techniques by coupling conventional methods with ultrasound, microwave, high pressure and supercritical carbon dioxide. The last section gives an insight on application of enzyme immobilization as a strategy for large scale extraction. Immobilization of enzymes on magnetic nanoparticles can be employed to enhance the operational performance of the system by multiple use of expensive enzymes making them industrially and economically feasible.
Extraction of various biomolecules by using enzyme assisted extraction. Display omitted
•Application of enzyme assisted extraction in the recovery of various biomolecules.•Enzymes disrupt the complex cell wall structure to release the active constituents.•Novel extraction methods coupled with enzyme assisted extraction is reviewed.•Enzyme immobilization as a strategy for large scale application is explored.•Magnetic nanoparticles are considered as potential carriers for enzyme immobilization.
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