Wide Range Of Polarities Research Articles

Dependence of hole’s effective mass on the spin polarization and temperature in quantum well

The effective mass of holes (m∗) in GaAs quantum wells is investigated as a function of spin polarization, temperature, and carrier density using the Hartree–Fock approximation. The results reveal m∗ initially decreases at low carrier densities before increasing with density. Additionally, as the interaction parameter increases, m∗ decreases rapidly. Especially, as the temperature rises to 200 K, m∗ asymptotically approaches a value of 0.45m0, where m0 is the electron mass. These findings provide insights into the influence of Coulomb interaction and exchange energy on the effective mass of semiconductors across a wide range of temperatures, spin polarizations, and densities.

A novel sample preparation method based on polarity grouping for comprehensive determination of 315 pesticides and other contaminants in wolfberry by liquid chromatography-tandem mass spectrometry

A novel sample preparation method based on polarity grouping was developed for the comprehensive determination of 315 undesirable low-weight organic pollutants ranging from polar to weakly polar in wolfberry. The method involves the swelling of the sample in ammonium acetate buffer, two-phase extraction, three-phase extraction, and dispersive solid phase extraction (D-SPE) with the assistance of low-temperature centrifugation and analysis by ultrahigh performance liquid chromatography coupled with electrospray ionization tandem mass (UHPLC-ESI-MS-MS) by using the multiple reaction monitoring mode. The recoveries of the analytes with wide range of polarity were satisfactory. The matrix-fortified standard calibration curves were compared for quantification. The results of linearity were satisfactory with linear regression coefficients (R) ranging from 0.9901 to 1.000. The limits of quantification ranged from 1 μg/kg to 10.0 μg/kg, indicating the compliance of products with legal tolerances. The average recoveries for spiked wolfberry were in the range of 69.3 %–145.2 % with RSD values of 0.2 %–28.6 %. The inter-day precision was in the range of 0.2 %–27.0 %. For over 90 % of the analytes, the recoveries were 70 %–120 % with RSD values below 20 %. The application of this method in routine monitoring programs would imply a drastic reduction of both effort and time.

Hair analysis of selected drug-facilitated sexual assault substances using green supramolecular solvent extraction and LC-MS/MS analysis

Drug-facilitated sexual assault (DFSA) investigations require the consumption history of certain drugs by the victim. Hair; as a keratinized biological sample, offers the possibility to perform retrospective quantitative analysis due to its large window of detection in comparison to other biological matrices. Many analytical methods have been reported to determine class-specific DFSA substances. However, generic methods able to determine multiclass DFSA substances and which are also more sustainable remain pending. In this paper, we develop an efficient and eco-friendly generic single-step extraction method, based on the use of a supramolecular solvent (SUPRAS) made up of 1,2-hexanediol, to extract benzodiazepines, z-hypnotic compounds, cocaine and metabolites, amphetamine derivatives and other miscellaneous compounds involved in DFSA from hair. The proposed method offers a high extraction recovery (>86%) and acceptable matrix effects for 91% of the 23 tested substances, which cover a wide polarity range (log P from − 0.3 to 7.0). The estimated method detection and quantification limits were in the ranges 0.1–24.2 pg/mg and 0.4–80 pg/mg, respectively, and were lower than the recommended drug cut-off levels for all the studied substances, except for 11-nor-Δ9-tetrahydrocannabinol-9-carboxylic acid. This fast and environmentally friendly method has been successfully applied to quantify DFSA substances in different hair samples.

Predicting partitioning from low density polyethylene to blood and adipose tissue by linear solvation energy relationship models.

The variety of polymers utilized in medical devices demands for testing of extractables and leachables according to ISO 10993-18:2020 in combination with ISO 10993-1:2018. The extraction of the materials involves the use of organic solvents as well as aqueous buffers to cover a wide range of polarity and pH-values, respectively. To estimate patient exposure to chemicals leaching from a polymer in direct body contact, simulating solvents are applied to best mimic the solubilization and partitioning behavior of the related tissue or body fluid. Here we apply linear solvation energy relationship (LSER) models to predict blood/water and adipose tissue/water partition coefficients. We suggest this predictive approach to project levels of potential leachables, design extraction experiments, and to identify the optimal composition of simulating extraction solvents. We compare our predictions to LSER predictions for commonly applied surrogates like ethanol/water mixtures, butanol, and octanol as well as olive oil, butanone, 1,4-dioxane for blood and adipose tissue, respectively. We therefore selected a set of 26 experimentally determined blood/water partition coefficients and 33 adipose tissue/water partition coefficients, where we demonstrate that based on the root mean squared error rmse the LSER approach performs better than surrogates like octanol or butanol and equally well as 60:40 ethanol/water for blood. For adipose tissue/water partitioning, the experimentally determined octanol/water partition coefficient performs best but the rmse is at the same range as our LSER approach based on experimentally determined descriptors. Further, we applied our approach for 248 extractables where we calculated blood/low density polyethylene (LDPE) and adipose tissue/LDPE partition coefficients. By this approach, we successfully identified chemicals of potential interest to a toxicological evaluation based on the total risk score.

Contribution of LDI and MALDI for the Characterization of a Lignocellulosic-Based Pyrolysis Bio-Oil.

In recent years, various alternatives to fossil fuels have been developed. One of them involves the production of bio-oils from lignocellulosic-based biomass through pyrolysis. However, bio-oils present numerous heteroatoms and, in particular, oxygen atoms that need to be removed by an upgrading process. To optimize these processes, it is necessary to have good knowledge of the composition of the bio-oils at the molecular level. This work aims to establish the usefulness of laser desorption ionization (LDI) and matrix-assisted laser desorption/ionization (MALDI) techniques on lignocellulosic biomass-based bio-oils. Using a Fourier transform ion cyclotron mass spectrometer (FTICR MS), we showed that MALDI gives more information than LDI. The selectivity of a series of MALDI matrices was investigated, showing that some matrices are selective toward compound families and others ionize a wider range of compounds. In this study, nine proton-transfer matrices and three electron-transfer matrices were used and compared to results obtained in LDI. Dithranol, acetosyringone, and graphene oxide were the three promising matrices selected from all matrices, giving an overall characterization of oxygenated classes in a bio-oil. They allowed the ionization of many more species covering a wide range of polarity, aromaticity, and mass with a homogeneous relative intensity for all molecular classes such as lignin-derivative species, sugars, and lipid-derivative species.

A General One-Step Synthesis of Alkanethiyl-Stabilized Gold Nanoparticles with Control over Core Size and Monolayer Functionality.

In spite of widespread interest in the unique size-dependent properties and consequent applications of gold nanoparticles (AuNPs), synthetic protocols that reliably allow for independent tuning of surface chemistry and core size, the two critical determinants of AuNP properties, remain limited. Often, core size is inherently affected by the ligand structure in an unpredictable fashion. Functionalized ligands are commonly introduced using postsynthesis exchange procedures, which can be inefficient and operationally delicate. Here, we report a one-step protocol for preparing monolayer-stabilized AuNPs that is compatible with a wide range of ligand functional groups and also allows for the systematic control of core size. In a single-phase reaction using the mild reducing agent tert-butylamine borane, AuNPs that are compatible with solvents spanning a wide range of polarities from toluene to water can be produced without damaging reactive chemical functionalities within the small-molecule surface-stabilizing ligands. We demonstrate that the rate of reduction, which is easily controlled by adjusting the period over which the reducing agent is added, is a simple parameter that can be used irrespective of the ligand structure to adjust the core size of AuNPs without broadening the size distribution. Core sizes in the range of 2-10 nm can thus be generated. The upper size limit appears to be determined by the nature of each specific ligand/solvent pairing. This protocol produces high quality, functionally sophisticated nanoparticles in a single step. By combining the ability to vary size-related nanoparticle properties with the option to incorporate reactive functional groups at the nanoparticle-solvent interface, it is possible to generate chemically reactive colloidal building blocks from which more complex nanoparticle-based devices and materials may subsequently be constructed.

Simultaneous analysis of highly polar and multi-residue-type pesticides by heart-cutting 2D-LC-MS

Liquid chromatography-mass spectrometry (LC-MS) is currently the gold-standard technique for the analysis of non-volatile small organic molecules. However, one-dimensional liquid chromatography (1D-LC) cannot efficiently deal with mixtures of analytes with different physicochemical properties and, thus, specific chromatographic behaviour. As an alternative, this work proposes a two-dimensional liquid chromatography/high-resolution mass spectrometry (2D-LC-HRMS) approach for the simultaneous analysis of compounds with different polarities. It is based on the combination of hydrophilic interaction liquid chromatography (HILIC) in the first dimension (1D) and reversed-phase chromatography (RPLC) in the second dimension (2D), employing the heart-cutting methodology. The coupling between 1D and 2D was performed by a multiple heart-cutting (MHC) interface equipped with an active solvent modulation (ASM) valve. The aim of the study was the development of a 2D-LC methodology able to (i) acquire the 1D and 2D content by MS in a single analytical run, avoiding the loss of information caused by the MHC algorithm for filling the sampling loops; (ii) overcome the breakthrough problem caused by solvent incompatibility, modifying the 2D gradient during the ASM phase for this purpose. To evaluate the 2D-LC approach, pesticide residue analysis was proposed, selecting 20 pesticides covering a wide range of polarities (log Kow from −3.2 to 4.3) and including some of the so-called single residue method pesticides because of the difficulty of including them in 1D-LC multi-residue methods with satisfactory chromatographic resolution. The proposed strategy was to transfer in a single cut the void volume from the HILIC separation (consisting of the nonpolar pesticides) to the 2D for analysis under RPLC conditions. The developed assembly was assessed in a vegetable matrix (tomato) employing a hybrid QuEChERS/QuPPe sample treatment based on acetonitrile and methanol extraction. The proposed setup may be extended for 2D-LC applications where it is essential to acquire the entire content of both dimensions in a single data file just by coupling a selection valve to the MHC interface.

Broad-range extraction of highly polar to non-polar organic contaminants for inclusive target analysis and suspect screening of environmental samples

The lack of carefully optimized extraction techniques for the analysis of compounds with diverse polarities limits the identification of toxic pollutants in aqueous environmental matrices, particularly those that are considered persistent and mobile organic compounds (PMOCs). Tailored extraction techniques for specific classes of chemicals often result in very low to no extraction of either very polar or relatively non-polar chemicals, depending on the sorbent used. Hence, it is crucial to develop a balanced extraction for a wider range of polarity, especially for non-target analysis of chemical residues, in order to capture the occurrence of the full profile of micropollutants. Herein, a tandem solid-phase extraction (SPE) technique incorporating both hydrophilic-lipophilic balance (HLB) and mixed-mode cation exchange (MCX) sorbents was developed to extract and analyze 60 model compounds with a wide range of polarities (log Kow from ‐1.9 to 5.5) from untreated sewage matrices. Extraction efficiencies were assessed in NanoPure™ water and untreated sewage samples; 51 compounds in NanoPure™ water and 44 compounds in untreated sewage had ≥60 % extraction recoveries using the developed tandem SPE method. The method limits of detection ranged from 0.25 to 88 ng/L in untreated sewage matrix. The applicability of the extraction method was demonstrated in untreated wastewater samples; using the tandem SPE for suspect screening analysis captured an additional 22 compounds that were not extracted when using the HLB sorbent only. The optimized SPE method was also evaluated for the extraction of per- and polyfluoroalkyl substances (PFAS) by analyzing the same sample extracts under negative electrospray ionization liquid chromatography-tandem mass spectrometry (LC-MS/MS). The wastewater samples revealed the presence of sulfonamide-, sulfonic-, carboxylic-, and fluorotelomer sulfonic- PFAS with chain lengths 8, 4–8, 4–9, and 8, respectively, indicating that the tandem SPE procedure provides an efficient one-step extraction for the analysis of PMOCs that include pharmaceuticals, pesticides, and PFAS.

Recent advances in emerging application of functional materials in sample pretreatment methods for liquid chromatography-mass spectrometry analysis of plant growth regulators: A mini-review

Plant growth regulators (PGRs) are a class of small molecular compounds, which can remarkably affect the physiological process of plants. The complex plant matrix along with a wide polarity range and unstable chemical properties of PGRs hinder their trace analysis. In order to obtain a reliable and accurate result, a sample pretreatment process must be carried out, including eliminating the interference of the matrix effect and pre-concentrating the analytes. In recent years, the research of functional materials in sample pretreatment has experienced rapid growth. This review comprehensively overviews recent development in functional materials covering one-dimensional materials, two-dimensional materials, and three-dimensional materials applied in the pretreatment of PGRs before liquid chromatography-mass spectrometry (LC-MS) analysis. Besides, the advantages and limitations of the above functionalized enrichment materials are discussed, and their future trends have been prospected. The work could be helpful to bring new insights for researchers engaged in functional materials in sample pretreatment of PGRs based on LC-MS.

Highly-Selective Analytical Strategy for 90 Pesticides and Metabolites Residues in Fish and Shrimp Samples.

The analysis of pesticide residues in aquatic products is challenging due to low residue levels and the complex matrix interference. In this study, we developed a simple, fast method for the trace analysis of 90 pesticides and metabolites in aquatic products. The analytes covered a wide polarity range with log Kow (log octanol-water partition coefficient) ranging from -1.2 to 6.37. Grass carp (Ctenopharyngodon idellus) and prawn (Penaeus chinensis) samples were chosen to validate the quantification method. The samples were extracted by 0.2% formic-acetonitrile, cleaned by solid-phase extraction (PRiME HLB), and analyzed by high performance liquid chromatography-tandem mass spectrometry. The results showed good linearities for the analytes and were observed in the range of 0.05-50 μg/L. The recoveries of the method were within 50.4-118.6%, with the relative standard deviations being lower than 20%. The limits of quantifications (LOQs) of the method were in the range of 0.05-5.0 μg/kg, which were superior to values compared with other research. The developed method was applied to detect pesticide residues in prawn samples from eastern coastal areas of China. Three herbicide residues of diuron, prometryn, and atrazine were detected in prawn samples. The method was sensitive and efficient, which is of significance in expanding the screening scope and improving the quantitative analysis efficiency in aquatic products.

Metal-Organic Framework Nanoparticles with Universal Dispersibility through Crown Ether Surface Coordination for Phase-Transfer Catalysis and Separation Membranes.

Dispersing metal-organic framework (MOF) solids in stable colloids is crucial for their availability and processibility. Herein, we report a crown ether surface coordination approach for functionalizing the surface-exposed metal sites of MOF particles with amphiphilic carboxylated crown ether (CEC). The surface-bound crown ethers significantly improve MOF solvation without compromising the accessible voids. We demonstrate that CEC-coated MOFs exhibit exceptional colloidal dispersibility and stability in 11 distinct solvents and six polymer matrices with a wide range of polarities. The MOF-CEC can be instantaneously suspended in immiscible two-phase solvents as an effective phase-transfer catalyst and can form various uniform membranes with enhanced adsorption and separation performance, illustrating the effectiveness of crown ether coating.

Metal‐Organic Framework Nanoparticles with Universal Dispersibility through Crown Ether Surface Coordination for Phase‐Transfer Catalysis and Separation Membranes

AbstractDispersing metal‐organic framework (MOF) solids in stable colloids is crucial for their availability and processibility. Herein, we report a crown ether surface coordination approach for functionalizing the surface‐exposed metal sites of MOF particles with amphiphilic carboxylated crown ether (CEC). The surface‐bound crown ethers significantly improve MOF solvation without compromising the accessible voids. We demonstrate that CEC‐coated MOFs exhibit exceptional colloidal dispersibility and stability in 11 distinct solvents and six polymer matrices with a wide range of polarities. The MOF‐CEC can be instantaneously suspended in immiscible two‐phase solvents as an effective phase‐transfer catalyst and can form various uniform membranes with enhanced adsorption and separation performance, which highlights the effectiveness of crown ether coating.

Supramolecular solvents for making comprehensive liquid-liquid microextraction in multiclass screening methods for drugs of abuse in urine based on liquid chromatography-high resolution mass spectrometry

Multiclass screening methods involving hundreds of structurally unrelated compounds are becoming essential in many control labs and research areas. Accurate mass screening of a theoretically unlimited number of chemicals can be undertaken using liquid chromatography coupled to high resolution mass spectrometry (LCHRMS), but the lack of comprehensive sample treatments hinders this unlimited potential. In this research, the capability of supramolecular solvents (SUPRAS) for making comprehensive liquid-liquid microextraction (LLME) in multiclass screening methods based on LCHRMS was firstly explored. For this purpose, a SUPRAS made up of 1,2-hexanediol, sodium sulphate and water was synthesized directly in the urine and applied to compound extraction and interference removal in the screening of eighty prohibited substances in sports by LC-electrospray ionization-time of flight mass spectrometry. Selected substances included a wide range of polarities (log P from -2.4 to 9.2) and functionalities (e.g. alcohol, amine, amide, carboxyl, ether, ester, ketone, sulfonyl, etc.). No interfering peaks were observed for any of the 80 substances investigated. Around 84–93% of drugs were efficiently extracted (recoveries 70–120%) and 83–94% of the analytes did not show matrix effects (±20%) in the ten tested urines. Method detection limits for the drugs were in the interval 0.002–12.9 ng mL−1, which are in accordance with the Minimum Required Performance Levels values established by the World Anti-Doping Agency. The applicability of the method was evaluated by the screening of thirty-six blinded and anonymized urine samples, previously analyzed by gas or liquid chromatography-triple quadrupole. Seven of the samples lead to an adverse analytical finding in line with the results obtained by the conventional methods. This research proves that LLME based on SUPRAS constitutes an efficient, economic, and simple sample treatment in multiclass screening methods, an application that is unaffordable for conventional organic solvents.

Ultrasonic sample introduction combined with flame assisted thermal ionization: Pretreatment-free direct mass spectrometry analysis for fraction collecting tubes of preparative liquid chromatography

Ultrasonic sample introduction combined with flame assisted thermal ionization mass spectrometry (USI-FATI-MS) was developed to monitor the fractions of preparative liquid chromatography. Recently, ultrasound-based sample introduction techniques have achieved great advance in the field of high-throughput analysis. However, it is still a challenge to directly apply these existing techniques to the analysis of macro volume samples (mL level). In this work, ultrasonic sample introduction combined with flame assisted thermal ionization was used for pretreatment-free direct mass spectrometry analysis of micro to macro volume samples (μL-mL level). Utilizing this unique design of ultrasonic sample introduction, liquid sample in the container can be quickly atomized to the gas phase without contact. Then, due to the flame assisted thermal ionization source, desolvation and ionization of the sample droplets will occur immediately. USI-FATI-MS has shown excellent sensitivity, repeatability and great compatibility to solvents and compounds with a wide range of polarity. As a proof of concept, USI-FATI-MS has been applied for rapid monitoring and identification of purified synthetic and natural products in fractions.

On-line reversed-phase liquid chromatography x supercritical fluid chromatography coupled to high-resolution mass spectrometry: A powerful tool for the characterization of advanced biofuels

Bio-oils obtained by thermochemical or biochemical conversion of biomass represent a promising source of energy to complement fossil fuels, in particular for maritime or air transport for which the use of hydrogen or electricity appears complicated. As these bio-oils are very rich in water and heteroatoms, additional treatments are necessary before they can be used as biofuel. In order to improve the efficiency of these treatments, it is important to have a thorough knowledge of the composition of the bio-oil. The characterization of bio-oils is difficult because they are very complex mixtures with thousands of compounds covering a very wide range of molecular weight and polarity. Due to the high degree of orthogonality between the two chromatographic dimensions, the on-line combination of reversed-phase liquid chromatography and supercritical fluid chromatography (on-line RPLC x SFC) can significantly improve the characterization of such complex matrices. The hyphenation was optimized by selecting, in SFC, the stationary phase, the co-solvent, the make-up solvent prior to high resolution mass spectrometry (HRMS) and the injection solvent. Additionally, a new interface configuration is described. Quality descriptors such as the occupation of the separation space, the peak shapes and the signal intensity were considered to determine the optimal conditions. The best results were obtained with bare silica, a co-solvent composed of acetonitrile and methanol (50/50, v/v), a make-up solvent composed of methanol (90%) and water (10%) with formic acid (0.1%), an addition of co-solvent through an additional pump for SFC separation in a 2.1 mm column, and an hydro-organic solvent as injection solvent. The optimized setup was used to analyze two microalgae bio-oils: the full bio-oil coming from hydrothermal liquefaction and Soxhlet extraction of microalgae, and the gasoline cut obtained after distillation of the full bio-oil. Results in on-line RPLC x SFC-qTOF were particularly interesting, with very good peak shapes and high reproducibility. Moreover, the high degree of orthogonality for microalgae bio-oils of RPLC and SFC was highlighted by the very large occupation of the separation space. Isomeric profiles of compound families could be obtained in RPLC x SFC-qTOF and many isomers not separated in SFC alone were separated in RPLC and vice versa, thus showing the complementarity of the two chromatographic techniques.

An improved microfluidic device to enhance the enrichment factors in liquid phase microextraction: application to the simultaneous extraction of polar and non-polar acids in biological samples

A new microfluidic device to enhance the enrichment factor in miniaturized systems is proposed. The microfluidic system was design for liquid phase microextractions, and it was applied to the simultaneous extraction of acidic compounds of a wide range of polarity (0.5 < log P < 3). The device operated under stagnant acceptor phase conditions and all the operational parameters involved were optimized. Tributyl phosphate was found to be a new highly efficient supported liquid membrane to simultaneously extract analytes of very different polarities. The optimal donor and acceptor phase were pH 2 and pH 13, respectively. The donor flow rate and the extraction time were investigated simultaneously, offering great versatility with high enrichment factors (EFs). Limits of quantitation were within 0.02 and 0.09 µg mL−1 for all compounds at 10 µL min−1 as donor flow rate and 20-min extractions, offering EFs between 11 and 18 with only 200-µL sample volume consumption. The method was successfully applied to human urine samples, observing recoveries between 47 and 90% for all compounds. This new proposed microfluidic system increases the wide range of applications, especially when the analytes are present in lower concentrations in the sample.Graphical

Diluting modulation-based two dimensional-liquid chromatography coupled with mass spectrometry for simultaneously determining multiclass prohibited substances in cosmetics

Developing efficient and comprehensive screening methods for prohibited substances in cosmetics is critical for ensuring the quality and safety of cosmetics used in everyday life. This study proposed a heart-cutting two-dimensional liquid chromatography-mass spectrometry (2D-LC-MS) method based on online diluting modulation for detecting multiclass prohibited substances in cosmetics. The 2D-LC-MS method combines HILIC and RPLC techniques. Compounds near the dead time that the first dimensional HILIC could not separate were transferred to the second dimensional RPLC by valve switch, achieving good separation with a wide range of polarities. Moreover, the online diluting modulation solved the problem of mobile phase incompatibility, realizing an excellent column-head focusing effect and reducing the loss of sensitivity. Besides, the first dimensional analysis did not restrict the flow rate of the second dimensional analysis owing to the diluting modulation. We demonstrated the 2D-LC-MS system by determining 126 prohibited substances in cosmetic products, including hormones, local anesthetics, anti-infectives, adrenergic agents, antihistamines, pesticides, and other chemicals. All correlation coefficients of the compounds were above 0.9950. The LODs and the LOQs ranged from 0.000259 ng/mL to 16.6 ng/mL and 0.000864 ng/mL to 55.3 ng/mL, respectively. The RSDs% for intra-day and inter-day precision were within 6% and 14%, respectively. Compared with conventional one-dimensional liquid chromatography methods, the established method expanded the analytical coverage of cosmetics-prohibited substances with reduced matrix effects for most compounds and improved sensitivity for polar analytes. The results indicated that the 2D-LC-MS method was a powerful tool for screening multiclass prohibited substances in cosmetics.

Influence of the fluid polarity on shear strength of sodium montmorillonite clay: A steered molecular dynamics study

Smectite clay minerals such as sodium montmorillonite (NaMt) are some of the main constituents of expansive clays. This work evaluated the mechanical response of NaMt intercalated with fluids having a wide range of polarities under various magnitudes of compression and fluid content using steered molecular dynamics (SMD) simulations. The shear strength parameters of the clay at the molecular scale, cohesion, and friction angle were quantitively evaluated. The simulation results indicated that the polarity of the fluids and the fluid content in the clay interlayer space played a vital role in shear stress versus shear strain response, the shear strength parameters, and nonbonded interactions energies upon mechanical loading of externally applied compressive stresses followed by shearing. The expansive clay's shear stress versus shear strain response depended on the normal stress and fluid polarity. This study showed the profound influence of the polarity of the fluids on the molecular shear strength behavior of swelling clays. Incorporating the clay-fluid molecular interactions and their role in shear response at the molecular scale is crucial for developing robust theories and tools for accurately predicting the shear strength properties of swelling clays for geotechnical and geoenvironmental applications.

Efficient strategies for preparative separation of iridoid glycosides and flavonoid glycosides from Hedyotis diffusa.

Efficient strategies for the preparative separation of iridoid glycosides and flavonoid glycosides from Hedyotis diffusa using preparative high-performance liquid chromatography combined with appropriate pretreatment technologies were developed. Four fractions (Fr.1-1, Fr.1-2, Fr.1-3, and Fr.2-1) were firstly isolated from the crude extract of Hedyotis diffusa by column chromatography with C18, resin, and silica gel materials, respectively. Then, corresponding separation strategies were developed according to the polarity and chemical constituents. High-polar compounds of Fr.1-1 were purified by hydrophilic reversed-phase liquid chromatography and hydrophilic interaction liquid chromatography mode. The combination of C18 and phenyl columns realized the complementary separation of iridoid glycosides in Fr.1-2. Meanwhile, the improved selectivity caused by the change of organic solvent in the mobile phase was utilized to realize the purification of flavonoid glycosides in Fr.1-3 and Fr. 2-1. Finally, 27 compounds (purity>95%) mainly involving nine iridoid glycosides and five flavonoid glycosides were obtained. A complete strategy was established for the separation of a complex sample with a wide polarity range, to jointly solve the problems of enrichment of target components and separation of structural analogs.

Development of polypropylene membranes grafted with nanocellulose to analyze organic pollutants in environmental waters using miniaturized passive samplers based on liquid-phase microextraction

Reinforcing hollow polypropylene fibers with nanocellulose is a viable alternative for implementing miniaturized passive sampling devices (MPSDs) based on liquid-phase microextraction (LPME). This modification improves the extractive properties of microporous membranes, including the sensitivity to fluctuations in the uptake steps. The new material, polypropylene hollow fiber grafted with nanocellulose, was developed and characterized using X-Ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM) coupled with Energy Dispersive System (EDS) and Thermogravimetric (TGA) and Differential Thermal (DTA) analysis. The morphology type of the crystallite of cellulose most abundant after chemical regeneration was the CII (Celulose II) allomorphic. Sorption studies were carried out and revealed that the modified membrane could absorb 177% more water than its untreated commercial counterpart, making it suitable for long-term sampling. Miniaturized passive sampling devices were equipped with the new material, and the devices were deployed in situ for passive sampling of organic pollutants in environmental waters of marginal lagoons. Fingerprint analysis of samples was performed by comprehensive two-dimensional gas chromatography coupled with mass spectrometry and identified a variety of pollutants such as pesticides, plasticizers and prescription and illegal drugs and their metabolites. Therefore, these MPSDs can be employed for the sampling and long-term monitoring of water contaminants with a wide range of polarities.