Sample preparation is the most crucial step in the analytical procedure designed for implementation in any analytical application (food analysis, bionalysis, forensics, toxicology, environmental monitoring etc). It is the limiting factor in chemical analysis since it is time consuming and it can potentially introduce errors. No one can doubt that the best approach would be the direct introduction of the sample to the instrument; however, this is rarely feasible. Efficient sample pretreatment is inevitably required as the instrument technology has produced highly sophisticated and sensitive analytical equipment. Hence, the analytical scientists have to develop and apply a suitable sample preparation protocol that ensures that the composition of the sample remains unchanged, no impurities are introduced during handling, all interferences have been left back, and the analytes’ concentration is not only at detectable levels, but it can also be quantified precisely and accurately and that the matrix of the sample is compatible with the analytical technique. Extraction techniques are the most powerful tool available to analytical chemists and lab practitioners. Whether sorbent-based or solvent-based, extraction techniques provide the necessary tools to handle the sample in a way that can reveal all the important information. All advantages in instrumentation have been exploited to the fullest and the lifetime of the instrument is prolonged in a seamless operation mode. This entry collection aims to highlight some applications of extraction techniques in sample preparation.

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Topic Review
Extraction Techniques of Brassica By-Products
The Brassica genus (Brassicaceae family) is a large group of primarily herbaceous plants, one of the most important crops after soybean in world oilseed production, and as fresh vegetables, they are widely consumed throughout the year as part of salads or after cooking. This genus includes various types of well-known species such as cabbage, broccoli, brussels sprouts, kale, kohlrabi, pak choi, rape, turnip, mustard, and cress. Brassica plants are also distinguished from other vegetable plants by their high functional (phenolic and organosulfur compounds) and nutritional properties. Food losses and waste reduction are a worldwide challenge involving governments, researchers, and food industries. Therefore, by-product revalorization and the use of key extracted biocompounds to fortify innovative foods seems an interesting challenge to afford.
  • 129
  • 12 May 2023
Topic Review
Contaminant Cocktails of High Concern in Honey
Environmental pollution is a crucial problem in our society, having a better understanding of its consequences, which include the increase of contaminant cocktails present in the environment. The contamination of honeybees can occur through their interaction with the nearby environment. Therefore, if honeybees are previously contaminated, there is a possibility of contamination of their products, such as honey as natural, or minimally processed, product, resulting from the honeybees’ activity.
  • 70
  • 14 Apr 2023
Topic Review
Green Extraction Techniques for Active Ingredients in Tea
The so-called “Green Extraction”—which is based on the design of different extraction processes for the reduction in energy consumption, as well as the usage of alternative solvents and renewable natural materials —was developed.
  • 229
  • 17 Feb 2023
Topic Review
Extracellular Vesicle-microRNAs as Diagnostic Biomarkers in Preterm Neonates
Neonates born prematurely (<37 weeks of gestation) are at a significantly increased risk of developing inflammatory conditions associated with high mortality rates, including necrotizing enterocolitis, bronchopulmonary dysplasia, and hypoxic-ischemic brain damage.
  • 97
  • 15 Feb 2023
Topic Review
Cerebral Organoid Glioma ‘GLICO’ Model for Drug Screening
Glioblastoma, a grade IV astrocytoma, is regarded as the most aggressive primary brain tumour with an overall median survival of 16.0 months following the standard treatment regimen of surgical resection, followed by radiotherapy and chemotherapy with temozolomide. The ability to understand and manipulate complex cancers such as glioblastoma requires disease models to be clinically and translationally relevant and encompass the cellular heterogeneity of such cancers. Therefore, brain cancer research models need to aim to recapitulate glioblastoma stem cell function, whilst remaining amenable for analysis. The development of 3D cultures has overcome some of these challenges, and cerebral organoids are emerging as cutting-edge tools in glioblastoma research. The opportunity to generate cerebral organoids via induced pluripotent stem cells, and to perform co-cultures with patient-derived cancer stem cells (GLICO model), has enabled the analysis of cancer development in a context that better mimics brain tissue architecture.
  • 139
  • 31 Jan 2023
Topic Review
Natural Deep Eutectic Solvents for Sustainable Extraction Techniques
The analysis of foods is a comprehensive process of extraction, identification, and quantification of several classes of compounds from natural matrices. The detection and quantification of primary metabolites (sugars, amino acids, vitamins, and lipids), contaminants (toxins, heavy metals, and allergens), and secondary metabolites (polyphenolics, flavonoids, terpenes, and alkaloids) is a crucial practice for ensuring the safety and quality of foods and related functional products. Due to the variable structure of food analytes, a gap in a universal method suitable for the extraction and analysis of all compounds is lacking. Moreover, conventional extractants are usually made of organic solvents and common extraction techniques usually require a long extraction time to exhaust the matrix. The actual discussions about climatic changes provide a growing awareness of the scientific and industrial community to reduce the environmental impact by using sustainable processes. In general, the main principles of “green chemistry” are based on the design of processes aimed to reduce energy consumption and the use of eco-friendly solvents with less toxicity to the environment and human health.
  • 198
  • 09 Jan 2023
Topic Review
Supercritical Antisolvent Technique for the Preparation of Nanocatalysts
In an era where sustainability is becoming the main driving force for research and development, supercritical fluids-based techniques are presented as a very efficient alternative technology to conventional extraction, purification, and recrystallization processes. Supercritical antisolvent (SAS) precipitation is a novel technique that can replace liquid antisolvent precipitation techniques. Additionally, through the optimization of precipitation operating conditions, morphology, particle size, and particle size distribution of nanoparticles can be controlled. As an antisolvent, supercritical carbon dioxide (scCO2) is far more sustainable than its conventional liquid counterparts; not only does it have a critical point (304 K and 73.8 bar) on its phase diagram that allows for the precipitation processes to be developed so close to room temperature, but also its recovery and, consequently, the precipitated solute purification stage is considerably simpler. This technique can be used efficiently for preparing nanocatalysts to be used in biodiesel production processes.
  • 245
  • 21 Dec 2022
Topic Review
Froth Washing in Flotation
Froth flotation is a mineral processing technique that is popular when processing low-grade ores. It involves introducing chemically treated, finely ground ore in the form of a slurry into a flotation cell where the air is also added in the form of bubbles. The cell is agitated resulting in the air bubbles rising to the top and creating a froth, as bubbles rise, hydrophilic particles attach to the rising bubbles creating a froth which is collected in the weir or using launders for further treatment. The froth is washed using various froth-washing techniques to reduce entrainment and improve the grade of the froth. Froth washing can be achieved using froth washing jets or froth washing trays, this can be achieved internally/externally with regards to the position in the froth layer.
  • 308
  • 30 Nov 2022
Topic Review
Procedures for Extraction of Anthocyanins from Different Food
Anthocyanins are water-soluble pigments characterized by various intense colors found in fruits and vegetables. The extraction and separation of anthocyanins from plants is important, especially due to the instability of plant anthocyanins, selecting and optimizing. Anthocyanins are prone to degradation by several factors, including pH, temperature, oxygen, water activity, co-pigments and enzymes. Unwanted compounds, such as sugars, proteins, lipids, acids and other flavonoids, can also be removed from plant material by appropriate extraction methods. The most used method for anthocyanin extraction is the conventional one, solid–liquid extraction, also known as solvent extraction, during which anthocyanins can be dissolved in polar solvents (methanol/glycolic acid and acetone), followed by their quantification, achieved by using spectrophotometry, the differential pH method, which is a rapid and convenient quantitative assay. Starting from this point, it has developed and there are many anthocyanin-extraction methods, such as conventional solvent extraction (CSE), enzyme-assisted extraction (EAE), fermentation extraction (FE), supercritical fluid extraction (SFE) (CO2) extraction, microwave-assisted extraction (MAE), ultrasonic-assisted extraction (UAE), high-hydrostatic-pressure extraction (HHPE) and pressurized-liquid extraction (PLE). One of the most frequent techniques for obtaining anthocyanins from plants is conventional solvent extraction. In order to meet the demands of safety and environmental sustainability, new extraction technologies with shorter extraction periods and higher yields have been developed (e.g., PLE, EFS, UAE, MAE, EAE, etc.).
  • 671
  • 29 Nov 2022
Topic Review
Extraction of Metals from Copper Tailings through Leaching
A copper tailing is a residue, product of the flotation of sulfide minerals, which contain a variety of elements that can be valorized. The extraction of metals from copper tailings consist of applying metallurgical techniques, such as acid leaching or magnetic concentration, to obtain a valuable product. Currently, this is an important objective, given that mining operations have increased the generation of tailings. Acid leaching is a process that consists of dissolving a solid material, such as a tailing, by applying an acid solution. This process forms two final products: an insoluble solid, rich in aluminosilicates, and an acid liquid solution with different metal ions. Both products may have different characteristics and can be used for subsequent applications.
  • 470
  • 05 Dec 2022
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