Hydrophilic interaction liquid chromatography (HILIC) provides an alternative approach to effectively separate small polar compounds on polar stationary phases. The purpose of this work was to review ...the options for the characterization of HILIC stationary phases and their applications for separations of polar compounds in complex matrices. The characteristics of the hydrophilic stationary phase may affect and in some cases limit the choices of mobile phase composition, ion strength or buffer pH value available, since mechanisms other than hydrophilic partitioning could potentially occur. Enhancing our understanding of retention behavior in HILIC increases the scope of possible applications of liquid chromatography. One interesting option may also be to use HILIC in orthogonal and/or two-dimensional separations. Bioapplications of HILIC systems are also presented.
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The unique silver properties, especially in the form of nanoparticles (NPs), allow to utilize them in numerous applications. For instance, Ag NPs can be utilized for the production of electronic and ...solar energy harvesting devices, in advanced analytical techniques (NALDI, SERS), catalysis and photocatalysis. Moreover, the Ag NPs can be useful in medicine for bioimaging, biosensing as well as in antibacterial and anticancer therapies. The Ag NPs utilization requires comprehensive knowledge about their features regarding the synthesis approaches as well as exploitation conditions. Unfortunately, a large number of scientific articles provide only restricted information according to the objects under investigation. Additionally, the results could be affected by artifacts introduced with exploited equipment, the utilized technique or sample preparation stages. However, it is rather difficult to get information about problems, which may occur during the studies. Thus, the review provides information about novel trends in the Ag NPs synthesis, among which the physical, chemical, and biological approaches can be found. Basic information about approaches for the control of critical parameters of NPs, i.e. size and shape, was also revealed. It was shown, that the reducing agent, stabilizer, the synthesis environment, including trace ions, have a direct impact on the Ag NPs properties. Further, the capabilities of modern analytical techniques for Ag NPs and nanocomposites investigations were shown, among other microscopic (optical, TEM, SEM, STEM, AFM), spectroscopic (UV-Vis, IR, Raman, NMR, electron spectroscopy, XRD), spectrometric (MALDI-TOF MS, SIMS, ICP-MS), and separation (CE, FFF, gel electrophoresis) techniques were described. The limitations and possible artifacts of the techniques were mentioned. A large number of presented techniques is a distinguishing feature, which makes the review different from others. Finally, the physicochemical and biological properties of Ag NPs were demonstrated. It was shown, that Ag NPs features are dependent on their basic parameters, such as size, shape, chemical composition, etc. At the end of the review, the modern theories of the Ag NPs toxic mechanism were shown in a way that has never been presented before. The review should be helpful for scientists in their own studies, as it can help to prepare experiments more carefully.
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•Size, shape and chemical composition of AgNPs can be controlled during synthesis.•Artifacts and limitations of the utilized technique can lead to results misinterpretations.•Properties of AgNPs are strictly dependent on the synthesis route.•AgNPs cytotoxicity is a complex process, which related not only to Ag ions release.
Zeta potential is a surface characteristic formed on the solid surface and liquid interface. It is an interesting way to describe the surface properties of materials; thus, a series of four homemade ...polar embedded stationary phases that contain phosphate groups incorporated into hydrophobic ligands were investigated according to surface zeta potential. Measurements were carried out using Zetasizer Nano ZS for the stationary phases suspensions prepared in various solvent and solvent binary mixtures. The negative zeta potential values were obtained for most cases due to negatively charged residual silanols and phosphate groups. However, in some solvents: tetrahydrofuran, isopropanol, and toluene zeta potential are positive. Additionally, it was observed that the zeta potential seems to be independent of the type of silica gel used for the stationary phase synthesis.
Quantitative structure-retention relationships (QSRRs) have found numerous applications in analytical science. Since first adaptation of linear free energy relationships for process of ...chromatographic separation, the significant progress in development of QSRR models has been achieved. Models gained statistical significance and improved values of prediction accuracy as well as started to be applied for identification of proteins, metabolites in non-targeted analysis and determination of relative biological activities of solutes. The ongoing progress of development of QSRR models for different chromatographic systems may lead researchers to the reasonable question: how far are we from industrial scale application of QSRRs? The current review paper is aimed to discuss crucial points, achievements and recent advances, future perspectives in QSRR applications to reflect on this question.
•Approaches for adequate similarity assessment for application in QSRR are scarce.•Study of biological activity by QSRR is limited due to lack of commercial targets.•Analysis of interactions between solutes and phases can improve prediction accuracy.
•Lung cancer is a human health problem.•Analytical methods for detecting potential markers for cancer in breath samples.•Potential markers of cancer detection using statistical methods.
Objective: ...Evaluation of the potential of combined multivariate chemometric methods for seeking markers of lung cancer.
Methods: Statistical methods such as Mann-Whitney U test, discriminant function analysis (DFA), factor analysis (FA) and artificial neural network (ANN) were applied to evaluate the obtained data from GC/MS analysis of exhaled breath.
Results: The total number of compounds identified by GC/MS in human breath was equal to 88. The statistical analysis indicates seven analytes which have the highest discriminatory power. Cross validation of the obtained model shows that the sensitivity was 80% and the specificity was 91.23%, while for the test group the sensitivity and specificity were both 86.36%.
Conclusion: The application of combined statistical methods allowed to reduce the number of compounds to significant ones and indicates them as markers of lung cancer.
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•The techniques used for enzymes immobilization.•The types of capillary- and chip-based microfluidic reactors.•The strategies used for microreactors coupling with separation and ...detection systems.•Dual-enzymatic systems: tandem reactions in coupled microreactors or enzymes co-immobilization.
It is commonly known that enzymatic transformations are considerably more specific than classical chemical reactions which usually lead to formation of byproducts. That is why the enzymes are a powerful tool in the field of analytical chemistry. The main problems occurring while working with enzymes stem from their relatively high price and sensitivity to non-physiological conditions. The above mentioned disadvantages may be overcome through enzyme immobilization which allows for reusing the biocatalyst as long as it retains its activity. When the immobilization is performed correctly the enzymes are more stable and also more resistant to denaturation. Such an approach in combination with additional benefits of miniaturization, heterogeneous catalysis and flow-mode operation contributes to the various applications of the Immobilized Enzyme Reactors (IMERs) in particular, microfluidic (μ-IMERs). In the present review various types of μ-IMERs were described. Particular attention was paid to techniques of their preparation including immobilization strategies and technical solutions connected with their applications using both capillary and chip format.
In this review, recent advances in the methods of pre-treatment of plant material for the extraction of secondary metabolites with high biological activity are presented. The correct preparation of ...the material for extraction is as important as the selection of the extraction method. This step should prevent the degradation of bioactive compounds as well as the development of fungi and bacteria. Currently, the methods of preparation are expected to modify the particles of the plant material in such a way that will contribute to the release of bioactive compounds loosely bonded to cell wall polymers. This review presents a wide range of methods of preparing plant material, including drying, freeze-drying, convection drying, microwave vacuum drying, enzymatic processes, and fermentation. The influence of the particular methods on the structure of plant material particles, the level of preserved bioactive compounds, and the possibility of their release during the extraction were highlighted. The plant material pre-treatment techniques used were discussed with respect to the amount of compounds released during extraction as well their application in various industries interested in products with a high content of biologically active compounds, such as the pharmaceutical, cosmetics, and food industries.
The profiling and quantification of potentially toxic elements (PTEs) in honey from Poland was the main aim of this work. Due to the differences in botanical and geographical origin, 33 honey samples ...from various parts of Poland have been tested and compared to 12 samples taken from other countries, such as Australia, Bulgaria, Italy, Germany, Portugal, Romania and Turkey. The studied elements in honey samples were: As, Be, Cd, Co, Cr, Cu, Fe, Mg, Mn, Mo, Ni, Pb, Sb, V and Zn. In most cases, the analyzed samples of honey were characterized by the moderate values of analyzed PTEs. Only a few samples contained higher concentrations of copper and manganese were noted. The presence of cadmium and lead in the level below the background equivalent concentrations was measured in the tested samples.
•Salt type, its concentration, and pH values had an influence on the retention of ASOs for both silica and zwitterionic stationary phases in HILIC mode.•Zwitterionic stationary phase provided greater ...ASOs retention factors, greater peaks symmetry as well as more effective MOE separation.•Salt type, its concentration, and pH had a great impact on the ASOs MRM peak areas in HILIC mode.•Comparison of IP RP HPLC and HILIC mode coupled with tandem mass spectrometry regarding the MS sensitivity has shown that greater ASO MRM peak areas were obtained for IP RP HPLC.•HILIC coupled with MS/MS may be alternatively used for ASOs separation and determination.
The aim of the present investigation was application of hydrophilic interaction liquid chromatography as an alternative chromatographic approach for the study of antisense oligonucleotides. The influence of several mobile phases, differing with the salt type, their concentration and pH value on the retention and the separation of antisense oligonucleotides has been examined for this purpose. Four different stationary phases were also applied including unmodified silica, silica modified with the use of sulfobetaine groups, polyhydroxy and aminopropyl groups. Such wide range of tested conditions has been useful in better understanding of the retention mechanism of tested compounds. The results obtained during this investigation indicated that greater retention, greater peaks symmetry, as well as more effective separation of oligonucleotides, were obtained for the zwitterionic stationary phase. Moreover, the optimization of tandem mass spectrometry parameters with the use of Central Composite Design was performed and different mobile phases were tested to choose that one, which provided the greatest antisense oligonucleotides peak areas in Multiple Reaction Monitoring mode and consequently, the greatest possible sensitivity. Hydrophilic interaction liquid chromatography was compared with the ion pair chromatography, commonly used in the analysis of oligonucleotides. Both techniques were compared in terms of selectivity of separation as well as the sensitivity of their determination. Obtained results proved that ion pair chromatography provided better results in terms of separation efficiency and peak areas in Multiple Reaction Monitoring for tested conditions. However, these results do not preclude application of hydrophilic interaction liquid chromatography as an alternative chromatographic approach for the oligonucleotides analysis especially when a mobile phase without ion pair reagents is required.
Quantum dots prepared from carbon precursors are a rising star among novel trends in the field of carbon materials. The subject of this paper is the synthesis of carbon dots that can serve as a ...sensor for determination of heavy metals such as mercury. Carbon dots were obtained in this study with a fast method of microwave synthesis and application of citric acid with glutathione or thiourea. Both versions of carbon dots have optical properties, i.e. fluorescence; however, when thiourea was used as a doping element precursor, the dots made better sensors as – due to quenching by mercury ions – the carbon dots synthesized from citric acid and thiourea have more significant optical effect than those made form citric acid and glutathione. As-synthesized carbon dots had relative quantum yield (QY) as 26% and the limit of quantification when these dots were used was 5.4 μM. In order to test the sensor efficiency in real samples, river water and wastewater were used.
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•N,S-CDs were synthesized via a fast microwave method.•As the main source of carbon, citric acid was used and glutathione or thiourea as precursors of doping elements.•As-prepared carbon dots have optical properties as fluorescence.•Sensor quite well suited for mercury (II) determination was obtained with citric acid and thiourea.•The real sample as river water and wastewater were used to evaluate potential application.
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