Separation and identification of multicomponent mixture by thin-layer chromatography coupled with Fourier transform-infrared microscopy

A fast and convenient method based on coupled thin-layer chromatography (TLC) with Fourier transform infrared (FTIR) microscopy has been established for separation and identification of multicomponent mixtures. In this study, the method was developed and consummated with more perfect TLC spots transferral process and consistent FTIR testing conditions. A newly developed technique, solid-phase extract (SPE) was introduced for sample pre-treatment instead of using traditional column chromatography. It is a new field for SPE that has already been widely applied in many other fields. It not only overcomes the backwards (low separation efficiency, time consuming and solvent consumption) of column chromatography but also makes it much easier to choose an optimum TLC sheet and to set suitable TLC loading. With all the above-mentioned modifications and supplements, the analytical method of coupled TLC with FTIR microscopy for separation and identification of multicomponent mixtures becomes more convenient and more efficient. In addition, a very complex sample (a die-cast release agent) was used as an example to demonstrate the technique.     

Application of image analysis technique for the determination of thiophanate methyl by thin-layer chromatography

A simple and convenient thin-layer chromatography (TLC) method combined with image analysis technique was developed to determine thiophanate methyl. The detection of pesticide was based on iodine–azide reaction. Digital images of TLC plate chromatograms were analysed using TLSee software, and quantitative analysis was conducted. The linearity (0.3–3.0 µg per spot), sensitivity, accuracy and precision of the system were investigated.     

A Mini Review: Electrospun Hierarchical Nanofibers

Electrospinning is a technique that allows the fabrication of continuous fibers with diameters down to a few nanometers. This technique provides a convenient and versatile method for preparing hierarchical nanofibers from a rich variety of materials that include almost all soluble or fusible polymers. The polymers can be chemically modified and can also be tailored with additives. The method provides access to entirely new materials. Until now, electrospinning is also widely being applied in laboratory and industry.     

Supramolecular architectures of cellulose derivatives

Several cellulose derivatives belong to a special class of polymers called hairy-rod macromolecules which are used to generate well-defined supramolecular architectures by the Langmuir-Blodgett (LB) technique. In particular trimethylsilyl cellulose (TMSC) forms monomolecular films on the Langmuir-trough and is transferred onto hydrophobic substrates with a constant transfer ratio, as it does not undergo chemical changes in the film-building process. Silylated celluloses was regenerated which represents a convenient method for the generation of homogeneous ultrathin films with hydrophilic surfaces. The adsorption of polymers and dyes as well as biomolecules onto regenerated and modified cellulose LB films have been studied. In addition, chemical reactions, such as cycloaddition, desilylation and crosslinking reactions within single monolayers have been performed.     

Peptide recognition via hierarchical imprinting

Silica particles containing immobilised peptidic templates have been used for the generation of hierarchically imprinted polymers. The pores of the silica mould were filled with a mixture of monomers/initiator and polymerised, followed by dissolution of the silica template. This method leaves behind imprinted polymers with binding sites located at the surface, which are capable of recognising larger molecules with the same immobilised epitope. All the products resulting from solid-phase synthesis of peptides were characterised by elemental analysis, FT-IR spectroscopy and fluorescence microscopy. The hierarchically imprinted polymers generated from these products were characterised by elemental analysis, FT-IR spectroscopy, fluorescence microscopy, scanning electron microscopy (SEM) and nitrogen adsorption, providing evidence concerning the reproducibility of each step. The chromatographic properties of the materials have been investigated and the advantages of the immobilisation method have been proven. The materials exhibit selectivity for their templates and other structurally related dipeptides. Furthermore, the polymers proved to be capable of recognising larger peptides containing the immobilised sequence.     

Ambient ionisation mass spectrometry for the characterisation of polymers and polymer additives: A review

The purpose of this review is to showcase the present capabilities of ambient sampling and ionisation technologies for the analysis of polymers and polymer additives by mass spectrometry (MS) while simultaneously highlighting their advantages and limitations in a critical fashion. To qualify as an ambient ionisation technique, the method must be able to probe the surface of solid or liquid samples while operating in an open environment, allowing a variety of sample sizes, shapes, and substrate materials to be analysed. The main sections of this review will be guided by the underlying principle governing the desorption/extraction step of the analysis; liquid extraction, laser ablation, or thermal desorption, and the major component investigated, either the polymer itself or exogenous compounds (additives and contaminants) present within or on the polymer substrate. The review will conclude by summarising some of the challenges these technologies still face and possible directions that would further enhance the utility of ambient ionisation mass spectrometry as a tool for polymer analysis.     

Application of Image Analysis Technique for the Determination of Organophosphorus Pesticides by Thin-Layer Chromatography

JPC – Journal of Planar Chromatography – Modern TLC - A simple and convenient thin-layer chromatography (TLC) method combined with image analysis technique was developed to determine...     

Melting and thermal history of poly(hydroxybutyrate-co-hydroxyvalerate) using step-scan DSC

Melting behaviour and crystal morphology of poly(3-hydroxybutyrate) (PHB) and its copolymer of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) with various hydroxyvalerate (HV) contents [5 wt.% (PHB5HV), 8 wt.% (PHB8HV) and 12 wt.% (PHB12HV)] have been investigated by conventional DSC, step-scan differential scanning calorimetry (SDSC) and hot-stage polarised optical microscopy (HSPOM). Crystallisation behaviour of PHB and its copolymers were investigated by SDSC. Thermal properties were investigated after different crystallisation treatments, fast, medium and slow cooling. Multiple melting peak behaviour was observed for all polymers. SDSC data revealed that PHB and its copolymers undergo melting–recrystallisation–remelting during heating, as evidenced by exothermic peaks in the IsoK baseline (non-reversing signal). An increase in degree of crystallinity due to significant melt–recrystallisation was observed for slow-cooled copolymers. PHB5HV showed different crystal morphologies for various crystallisation conditions. SDSC proved a convenient and precise method for measurement of the apparent thermodynamic specific heat (reversing signal) HSPOM results showed that the crystallisation rates and sizes of spherulites were significantly reduced as crystallisation rate increased.     

Synthesis,characterization and performance evaluation of long chain methacrylate-octene copolymer for lubricant formulation

Abstract

In this study, the authors synthesized myristyl methacrylate monomers by esterification reaction of methacrylic acid and myristyl alcohol using conc. H₂SO₄ as catalyst. Homopolymer of the prepared ester was synthesized and a series of copolymers were prepared by varying the ratio between the ester and 1-octene by free radical polymerization using azobisisobutyronitrile as initiator. All the synthesized polymers were characterized by spectral studies (FT-IR and NMR) and their average molecular weights were determined by gel permeation chromatography (GPC). Thermogravimetric analysis (TGA) was selected as the method to investigate the thermal behavior of the polymers at high temperature. Performances of the polymers as additives, and their responses as flow improvers and viscosity modifiers in the base fluid were carefully assessed by standard methods in terms of pour point and viscosity index. In addition, photo micrographic image was employed to examine the wax crystallization behavior of the additives. The results of the experimental work showed that although the copolymers were thermally more stable than the homopolymer, the latter showed better flow improving efficiency and induced better viscosity modification. The viscosity modification and the pour point performance of the additives also depend on the concentration of the additives in the base fluid.     

A Review of Synthetic Polymer Characterization by Pyrolysis–GC–MS

Pyrolysis–GC with mass spectrometry detection (Py–GC–MSD) study of the thermal degradation products of synthetic polymers is reviewed. Due to the high heating speed, accurate temperature reproducibility and a wide temperature range, Py–GC–MSD has been applied successfully for polymer characterization. Introduction of samples using the pyrolysis carrier gas through the split injection port, followed by sub-ambient cryofocusing of the pyrolysis products, has shown to give reproducible chromatograms (pyrograms). One of the advantages of this method is that all compositions of the polymers and additives can be investigated without any pretreatment, providing important compositional and structural information in a simple way. The method is a convenient method for compositional analysis of complex polymer materials. The aim of this review is to describe the kinds of applications for which Py–GC–MSD has been found to be suitable; to present guidelines for method optimization; to survey innovations that have recently been developed or are currently being researched; to point to problems in our understanding of the pyrograms; and to suggest areas in which research efforts might be most effective in realizing the full potential of this technique.     

Characterization of polyether mixtures using thin-layer chromatography and matrix-assisted laser desorption/ionization mass spectrometry

Thin-layer chromatography (TLC) and matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) were combined to achieve characterization of polyether mixtures. Three polyethers, polyethylene glycol (PEG), polypropylene glycol (PPG) and polytetramethylene glycol (PTMG), or mixtures of these compounds, were studied. One shortcoming of mixture analysis of synthetic polymers using MALDI-MS is that individual polymers in the mixture may display different detection sensitivities. For example, the MALDI mass spectrum of an equimolar mixture of PEG, PPG and PTMG displayed a high intensity of PPG ions, while no PTMG ions were detectable; however, PTMG ions were detected after the mixture had been separated by TLC. This combined TLC and MALDI-MS analysis of a PPG polymer bearing reactive epoxy groups showed that the polymer contained byproducts with different end-groups. These byproducts were identified as chloro-substituted polymers formed during polymer synthesis. Our study shows TLC to be a rapid and low-cost separation technique, and that it can be combined with MALDI-MS to achieve effective analysis of synthetic polymers.     

A new lipidomics approach by thin-layer chromatography-blot-matrix-assisted laser desorption/ionization imaging mass spectrometry for analyzing detailed patterns of phospholipid molecular species

Thin-layer chromatography (TLC) is a highly established convenient technique for lipid separation and partial characterization of neutral and acidic glycosphingolipids (GSLs) and phospholipids, in mixtures. Meanwhile, imaging mass spectrometry (IMS) is a promising tool for lipidomics. However, some lipid classes are detected more sensitively than others, which can lead to suppression effects when complex mixtures are analyzed. Therefore to analyze complex lipid mixtures, a precise separation into the individual lipid classes is necessary. Here we present our highly sensitive and convenient analytical technology that combines TLC and IMS, namely the TLC-Blot–MALDI-IMS method, to visualize whole lipids and individual molecular species with high sensitivity compared with common staining methods. This method allows for easy visualization of all lipids with a linear range of approximately one order of magnitude and precision <16% RSD, making it useful for differential display analysis of lipids.     

Identification of species’ blood by attenuated total reflection (ATR) Fourier transform infrared (FT-IR) spectroscopy

Blood is one of the most common and informative forms of biological evidence found at a crime scene. A very crucial step in forensic investigations is identifying a blood stain’s origin. The standard methods currently employed for analyzing blood are destructive to the sample and time-consuming. In this study, attenuated total reflection (ATR) Fourier transform infrared (FT-IR) spectroscopy is used as a confirmatory, nondestructive, and rapid method for distinction between human and animal (nonhuman) blood. Partial least squares-discriminant analysis (PLS-DA) models were built and demonstrated complete separation between human and animal donors, as well as distinction between three separate species: human, cat, and dog. Classification predictions of unknown blood donors were performed by the model, resulting in 100 % accuracy. This study demonstrates ATR FT-IR spectroscopy’s great potential for blood stain analysis and species discrimination, both in the lab and at a crime scene since portable ATR FT-IR instrumentation is commercially available.     

Spectroscopic investigation of a ‘Virgin of Sorrows’ canvas painting: A multi-method approach

The investigation of unmatched ancient objects is an attentive and arduous activity to conservation scientists. An important aspect of art analysis is the question on sampling and avoiding damage on the artefact during the study. A possible way to maximize the information that is extracted from the historical object is using several sensitive micro-analytical techniques on the same micro samples. As an illustration of this multi-method approach, in this work, a canvas painting ‘Virgin of Sorrows’ was studied and its materials were analysed in order to roughly date and to authenticate this object of art. Proton induced X-ray emission (PIXE), neutron activation analysis (NAA), optical microscopy, scanning electron microscopy (SEM), micro-Raman spectroscopy (MRS) and Fourier transform infrared spectroscopy (FT-IR) were used, obtaining successful results. These methods allowed identifying the different inorganic pigments (iron oxide, carbon black, white lead, Prussian blue) as well as indigo. Optical microscopy and SEM revealed the layered structure of the samples, while FT-IR enabled to determine the nature of the varnish used (shellac). By using these complementary techniques, it was possible to identify the materials in the painting, which are indicative for the period of manufacturing the artwork.     

The rapid differentiation of Streptomyces isolates using Fourier transform infrared spectroscopy

Fifteen putative Streptomyces spp. isolated from soil were selected to be analysed using Fourier transform infrared (FT-IR) spectroscopy and 16S rRNA gene sequencing. Four colour groupings (groups 1–4) were obtained and described according to the colour of their substrate mycelia, aerial mycelia, spore mass and pigmentation. The dendrogram constructed using unsupervised cluster analysis of the FT-IR data was in good congruence with the four colour groups and the neighbour-joining phylogenetic tree for 16S rDNA sequencing. In particular, those isolates having 100% 16S rDNA similarities which are supposed to be from the same species can be separated from each other using FT-IR analysis. This high throughput method only takes 1–10 s to collect a FT-IR spectrum from each sample, and both 96- and 384-well microplates are available for automated analysis. FT-IR therefore presents itself as a rapid, whole-organism fingerprinting approach which can be used for preliminary differentiation of Streptomyces spp. at sub-species or strain level.     

Naturally derived green bio-additives

During the last few years, special attention has been paid by the lubricant industry towards vegetable oil-based lubricants due to their biodegradability, renewability and excellent tribological properties. But to maintain the biodegradability of the final lubricants, the additive in the lubricants must also be biodegradable. Hence, in our present work, multifunctional lubricating oil additive based on castor oil has been investigated as a less toxic, feasible alternative to traditional petroleum based additives. Homopolymer of castor oil and its copolymer with α-pinene were synthesized by a thermal method using azobisisobutyronitrile as a radical initiator. Characterization of the prepared polymers was performed by spectral analysis and gel permeation chromatography (GPC). Additive performances of each of the prepared polymers as viscosity index improvers/viscosity modifiers and pour point depressants were carefully evaluated. Photo micrographic image was used to study the effectiveness of the additives as pour point depressants. Thermogravimetric analysis (TGA) was conducted to investigate the thermal response of the additives at high temperature. Finally, biodegradability of all the polymers was tested against fungal pathogen by the disc diffusion method and soil burial test. The study illuminated excellent additive performances of the polymers and thus their potential for acting as entirely naturally derived green bio-additives for lube oil.     

Simultaneous isolation of seven compounds from Glehnia littoralis roots by off‐line overpressured layer chromatography guided by a TLC antioxidant autographic assay

A combinative method using overpressured layer chromatography (OPLC) and TLC bioautography against O₂^?? was developed to separate antioxidants from Glehnia littoralis roots. Through target‐directed isolation by the TLC bioautographic method, seven compounds including five antioxidants were rapidly isolated by OPLC and identified as 1‐linoloyl‐3‐palmitoylglycerol, facarindiol, panaxynol, isoimperatorin, β‐sitosterol, scopoletin, and umbelliferone from G. littoralis roots. This OPLC method is a very suitable separation technique for light‐sensitive polyacetylenes (panaxynol and facarindiol) with higher isolated yields compared to conventional open column chromatography. This is the first report on the separation of polyacetylenes by OPLC.     

Synthesis and characterisation of star-shaped liquid crystalline polymer with a POSS core

The star-shaped POSS-graft-LCP with POSS as the core and liquid crystal polymer, poly{6-(4?-octyloxyphenyl-4″-benzoyl)hexyl acrylate}, as arms was prepared by atom transfer radical polymerisation technique using octa(3-chloropropyl) polyhedral oligomeric silsesquioxane [POSS-(CH₂CH₂CH₂Cl)₈] as initiator. For comparison, the linear liquid crystal polymer, poly{6-(4?-octyloxyphenyl-4″-benzoyl)hexyl acrylate} (LLCP), was obtained by conventional radical polymerisation. Both liquid crystal polymers were characterised by FT-IR, ¹H NMR, ¹³C NMR, gel permeation chromatography, thermogravimetric analysis, differential scanning calorimetry, polarised optical microscopy and X-ray diffraction analysis. The liquid crystal phase behaviour research demonstrated that both liquid crystal polymers were reversible thermotropic nematic liquid crystal materials. The number of polymerisation degree of every arm attached on POSS in POSS-graft-LCP impacted greatly on the liquid crystal properties and only a small one was necessary for it to exhibit a broad liquid crystal range. Results further demonstrated that the special star-shaped topology of POSS and the eight arms attached helped POSS-graft-LCP form and stabilise liquid crystal phase easily. This research may further expand the way to star-shaped LCPs by employing a variety of (meth)acrylate and other vinyl liquid crystalline monomers.     

薄层色谱法测定聚苯乙烯的溶解度参数

本文采用薄层色谱法测定了聚苯乙烯的溶解度参数,其数值为9.10(cal/cm³)^1/2,这个结果和文献中其它方法所得的结果甚为一致,而这个方法却比文献中其它测定高分子溶解度参数的方法既方便又简单,所以这是一种测定高分子溶解度参数的较好方法。     

Nanoreinforced hemicellulose-based hydrogels prepared by freeze–thaw treatment

A novel hybrid hydrogel was prepared from hemicelluloses, polyvinyl alcohol, and chitin nanowhiskers by the freeze–thaw technique. The hydrogel was characterized by Fourier-transform infrared (FT-IR) spectrometry, scanning electron microscopy, X-ray diffraction analysis, cross-polarization (CP)/magic-angle spinning (MAS) ¹³C nuclear magnetic resonance (NMR), and swelling property and compressive strength measurements. Atomic force microscopy images of chitin implied that the size of whiskers reached nanometer level with average length of about 200 nm and width of 40 nm. The FT-IR and NMR results indicated that physical cross-linking rather than chemical reaction occurred during the gelation process. The mechanical properties of the hydrogels were significantly improved with increasing proportion of chitin nanowhiskers, with the highest compressive stress of 9.6 MPa being found for Gel-0.5. The results showed that the repeated freeze–thaw cycles induced physical cross-linking of packed chains by hydrogen bonds among the polymers, and the concentration of chitin nanowhiskers affected the hydrogel morphology and properties. It is suggested that hydrogels with good mechanical properties can be successfully prepared by this physical method, offering promise for tissue engineering applications.