Diamines as switchable-hydrophilicity solvents with improved phase behaviour

Applications of New Generation Solvents for Extraction of Herbal Products Prior to Atomic and Molecular Analysis

In this review, an up to date and current knowledge of some of the green solvents, which includes supercritical fluids extraction (SFE), switchable polarity solvents (SPS), and natural deep eutectic solvents (NADES) are discussed with more emphasis on the extraction of active components of herbal products. Different scientific articles and books have been researched and reviewed to explain the applications of new generation solvents for extraction of herbal products prior to atomic and molecular analysis from the past until now. Currently, the most of techniques used in processing herbal products involve the use of extraction methods. Therefore, trends in extraction methods focuses mainly on finding reasonable solutions that minimizes the use of toxic solvents and allows the usage of renewable and green solvents from natural products, which ensure high quality and safe extracts. In future, SFE is definitely going to be on the industrial scale due to its numerous applications in the large scale especially for herbal, food, cosmetics and pharmaceutical products etc.

A Diamine-Oriented Biorefinery Concept Using Ammonia and Raney Ni as a Multifaceted Catalyst

Diamines are important industrial chemicals. In this paper we outline the feasibility of lignocellulose as a source of diol-containing molecules. We also illustrate the possibility of turning these diols into their diamines in good to excellent yields. Central to these transformations is the use of commercially available Raney Ni. For diol formation, the Raney Ni engages in hydrogenation and often also demethoxylation, that way funneling multiple components to one single molecule. For diamine formation, Raney Ni catalyzes hydrogen-borrowing mediated diamination in the presence of NH₃.

Scopes of Bioanalytical Chromatography–Mass Spectrometry

The areas of application of modern bioanalytical chromatography–mass spectrometry are so extensive that any attempt to systematize them becomes subjective. It would be more correct to say that there is no such area of biology and medicine where chromatography–mass spectrometry would not find application. This article focuses on the areas of application of this technique that are either relatively new or insufficiently covered in recent reviews. State-of-the-art bioanalytical techniques have become multitargeted in terms of analytes and standardized in terms of matrices. The ability to detect trace concentrations of analytes in the presence of a huge number of biomatrix macrocomponents using chromatography–mass spectrometry is especially important for bioanalytical chemistry. In the target-oriented determination of persistent organic pollutants by chromatography–mass spectrometry, the main problem is the expansion of the list of analytes, including isomers. In the detection of exposures to unstable toxicants, the fragmented adducts of xenobiotics with biomolecules become target biomarkers along with hydrolytic metabolites. The exposome reflects the general exposure of a human being to total xenobiotics and the metabolic status reflects the physiological state of the body. Chromatography–mass spectrometry is a key technique in metabolomics. Metabolomics is currently used to solve the problems of clinical diagnostics and anti-doping control. Biological sample preparation procedures for instrumental analysis are being simplified and developed toward increasing versatility. Proteomic technologies with the use of various versions of mass spectrometry have found application in the development of new methods for diagnosing coronavirus infections.

Sustainable green solvents for microextraction techniques: Recent developments and applications

The development and application of alternative green solvents in analytical techniques consist of trends in sample preparation, since this subject represents an important step toward sustainability in experimental procedures. This review is focused on the main theoretical aspects related to deep eutectic solvents (DES), switchable hydrophilicity solvents (SHS) and supramolecular solvents (SUPRAS). Recent applications are highlighted, particularly for the extraction of different analytes from environmental, biological and food matrices. Moreover, novel configurations are emphasized, aiming for efficient, automated and high-throughput procedures. This review also provides some critical points regarding the use of these solvents and their green aspects.

Molecular dynamics simulation of CO2-switchable surfactant regulated reversible emulsification/demulsification processes of a dodecane-saline system

CO2-Switchable surfactants are of great potential in a wide range of industrial applications related to their ability to stabilize and destabilize emulsions upon command. Molecular dynamics simulations have been performed to reveal the fundamental mechanism of the reversible emulsification/demulsification processes of a dodecane-saline system by a CO2-switchable surfactant that switches between active (i.e., N'-dodecyl-N,N-dimethylacetamidinium (DMAAH+)) and inactive (i.e., N'-dodecyl-N,N-dimethylacetamidine (DMAA)) forms. The density profiles indicate that DMAAH+ could increase the oil-water interfacial thickness to a greater extent compared to DMAA. DMAAH+ could sharply reduce the interfacial tension of the dodecane-saline system, while DMAA only exhibits a limited decrease, which is in accordance with the experimental observation that DMAAH+/DMAA can reversibly emulsify/demulsify alkane-water systems. Our simulations showed that both the number and lifetime of hydrogen bonds (HBs) between DMAA and water are almost equal to those between DMAAH+ and water. In DMAA, the N atom connecting with the alkyl tail acted as a HB acceptor, while the N atom attached by a proton in DMAAH+ acted as a HB donor. Furthermore, the HBs between DMAAH+ and HCO3- at the interfaces are relatively limited. Hence, it is deduced that the HBs are insufficient to achieve the CO2-switchability of DMAA/DMAAH+. The Lennard Jones and coulombic potentials between DMAA/DMAAH+ and other species show that the coulombic potentials between DMAAH+ and water or anions (i.e., Cl- and HCO3-) sharply decrease with the increase of DMAAH+ and are much lower than those in models with DMAA. The enhanced coulombic interactions between DMAAH+ and anions lead to a remarkable reduction in interfacial tension and the emulsification of the alkane-saline system. Therefore, coulombic interactions are of crucial importance to the reversible emulsification/demulsification processes regulated by CO2-switchable surfactants, namely DMAAH+/DMAA.

Switchable solvent N, N, N', N'-tetraethyl-1, 3-propanediamine was dissociated into cationic surfactant to promote cell disruption and lipid extraction from wet microalgae for biodiesel production

Switchable solvent N, N, N', N'-tetraethyl-1,3-propanediamine (TEPDA) was proposed to extract lipids from wet Nannochloropsis oceanica with a 5% higher extraction efficiency than chloroform-methanol. It was found that TEPDA acted mainly as an organic solvent to soften and dissolve lipids, while a small amount of TEPDA was dissociated into tertiary amine ion, i.e.,(C₂H₅)₂N-(CH₂)₃-NH⁺(C₂H₅)₂. This cation acted as a surfactant to promote cell disruption and lipid separation. With moisture increasing from 0 to 84 wt%, more TEPDA was dissociated into cationic surfactant to induce local rearrangement of phospholipid bilayers in cell membranes through electrostatic interaction, resulting in the fractal dimension of disrupted cells increased from 1.49 to 1.66. Accordingly, the yield of fatty acid methyl ester (FAME) through transesterification of lipids extracted with TEPDA increased by 9%, while FAME yield from lipids extracted with chloroform and n-hexane decreased by 41% and 65%, respectively.

A green and low-cost method employing switchable hydrophilicity solvent for the simultaneous determination of antidepressants in human urine by gas chromatography - mass spectrometry detection

In this study, the use of switchable hydrophilicity solvent with a simple and low-cost lab-made device for the extraction procedure in homogeneous liquid-liquid microextraction is proposed for the first time in the determination of antidepressants in human urine. The antidepressants studied consisted of fluoxetine, amitriptyline, nortriptyline, imipramine, desipramine and sertraline. The optimization of the main parameters that can influence on the extraction efficiency was performed through multivariate approaches. The analytes were separated and identified by gas chromatography coupled to mass spectrometry (GC-MS). The optimal extraction conditions consisted of using N,N-dimethylcyclohexylamine (DMCHA) as the switchable hydrophilicity solvent (SHS), 500 µL of urine sample previously diluted with ultrapure water at 1:1 ratio (v/v), 200 μL of a mixture of SHS:HCl 6 mol L^-1 (1:1 v/v), 600 μL of NaOH 10 mol L^-1 and 3 min of extraction time. A volume of 40 µL of diphenylamine at concentration of 500 µg L^-1 (20 ng) was used as internal standard. The method developed was in-house validated, providing coefficients of determination higher than 0.995 for all analytes, limits of detection (LOD) from 0.02 to 0.88 µg L^-1, limits of quantification (LOQ) from 0.05 to 2.92 µg L^-1, relative recoveries of 68 to 102%, intra-day precision from 0.5 to 15.9%, inter-day precision from 4.2 to 19.3%, selectivity and robustness. The method proposed was successfully applied in five human urine samples from a Toxicological Information Center located in Porto Alegre (Brazil). The results demonstrated that the µP-SHS-HLLME approach is highly cost-effective, rapid, simple and environmentally-friendly with satisfactory analytical performance.

Recovery of extra-heavy oil and minerals from carbonate asphalt rocks by reactive extraction

Quite different from the Canadian oil sands, the Indonesian asphalt rocks proved to be carbonate unconventional oil ores. The strong interactions between asphalt and minerals make water-based extraction work poorly in separating this kind of ore. Herein, a reactive extraction process has been proposed to separate asphalt and mineral solids from the ores through dissolving the mineral solids (i.e., carbonate minerals, metal oxides, etc.) by acids (formic acid). It is evidenced that most of the asphalt could be recovered and collected on the top of the solution by generated CO₂. What's more, the unreacted formic acid could be recycled in this process. The dissolved metal ions could be efficiently recovered to obtain different by-products by chemical settling and crystallization. The amount of residual solids settled at the bottom of the reactor is very small. Further tests show that the reaction efficiency is highly dependent on the operational conditions, including temperature, stirring rate, acid dosage, concentration of acid, etc. It is also found that the reaction could allow minerals to be redistributed in different phases. Although some metal elements could be dissolved into solution, elements such as Fe, Al, S, Si, and Ti are observed to accumulate in asphalt froth. In addition to reacting with minerals, formic acid is also found to reduce asphalt viscosity. This reduction improves the reaction efficiency. Based on primary evaluations, the above findings suggest that the reactive extraction would be a potential process to exploit the Indonesian asphalt rocks (or other similar ores) due to its full recovery to all materials.

A reactive extraction was applied to recover heavy and minerals from carbonate asphalt rocks.