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Abstract  

A combined thermogravimetry/differential scanning calorimetry device (TG/DSC) was coupled to single photon ionisation mass spectrometry (SPI-MS) for evolved gas analysis (EGA). Single photon ionisation (SPI) was performed with a new type of VUV light source, the so called electron beam pumped rare gas excimer lamp (EBEL). SPI does not fragment molecules upon the ionisation process. Thus the molecular mass signature of the evolving gases from thermal composition of carbonaceous material can be directly on-line recorded. In this work the thermo-analytical data and the SPI-MS information on the released organics is presented and discussed for various samples. Namely biomass (soft and hard wood), fossil fuel (crude oil and coal) as well as a complex polymer (ABS) are investigated. The general potential of hyphenating thermal analysis and soft photo ionisation mass spectrometry (EBEL-SPI-MS) for fundamental and applied research and material analysis is discussed.

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A method was developed for effect-directed analysis (EDA) of the root extract of Pimpinella saxifraga L. High-performance thin-layer chromatography (HPTLC) was hyphenated with microchemical, biochemical, and biological assays as well as electrospray ionization– mass spectrometry (ESI–MS). This HPTLC–UV/Vis/FLD– EDA–MS method directly pointed to multi-potent compounds in the P. saxifraga L. root extract. 2,2-Diphenyl-1-picrylhydrazyl radical scavengers, acetylcholinesterase inhibitors, estrogen-effective compounds, antimicrobials against Gram-positive Bacillus subtilis bacteria, and Gram-negative Aliivibrio fischeri bacteria were discovered in the root extract. A first targeted characterization of four unknown multi-potent compounds was performed by HPTLC–ESI–MS and microchemical derivatizations. This highly streamlined effect-directed profiling is recommended for a fast and cost-efficient natural product search.

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Abstract  

Nuclear methods of analysis have advanced dramatically in recent years, and in many ways, techniques that once were viewed as a scientific curiosity and the toys of a few scientists working in large nuclear research establishments, are now semi-routine and can be applied even by young students. Large amounts of good analytical data are outputted from instruments having sophisticated embedded software. It is interesting to speculate on the directions that nuclear analytical techniques may take next: whether more multielement; more automation for vastly larger sample suites; extension to minor and major components of samples as well as trace components; coupling of nuclear methods to hyphenated methods. However, in some respects the resources needed to continue to develop and apply radioanalytical methods are on the wane: reactors and accelerators are being closed and fewer radiochemical specialists are being trained. The open question, is whether instrumental analysis techniques will offer more and better results with less effort, or be less equipment intensive? In this paper some personal reflections on nuclear actcivation methods and their trends are presented and discussed. Some mileposts in the development of the field and some unique and interesting applications (as implied by the paper title) are cited and discussed.

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Abstract  

The hyphenated thermal analysis-mass spectrometry technique (TA-MS) was applied for the investigation of the thermal behavior of reference and aged parchment samples. The kinetic parameters of the process were calculated independently from all recorded TA and MS signals. The kinetic analysis showed the distinct dependence of the activation energy on the reaction progress. Such behavior is characteristic for the multistage mechanism of the reaction. The comparison of the kinetic parameters calculated from the different signals i.e. TG, DSC, MS for H2O, NO and CO2, however, indicated that they were differently dependent on the aging of the sample. For the parchment samples, the aging almost does not change the kinetics of the decomposition calculated from the DSC data: the influence of aging seems to be too negligible to be detected by these techniques. On the other hand, the much more sensitive mass spectrometric technique applied to the kinetic analysis allowed monitoring of visible changes in the thermal behavior of the parchment samples due to the aging process. The influence of aging was especially visible when the MS signals of water and nitric oxide were applied for the determination of the kinetic parameters. The applied method of the kinetic analysis allowed also the prediction of the thermal behaviour of reference and aged parchment samples under isothermal and modulated temperature conditions. Presented results have confirmed the usefulness of thermoanalytical methods for investigating behaviour of such complicated systems as leather or parchment.

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There is no doubt that high-performance thin-layer chromatography (HPTLC) can be applied as a quantitative method if the technique is properly used. Densitometry is a commonly used detection mode for quantitation in HPTLC. The influence of instrumental settings on signal intensity, peak resolution, and peak positioning was rarely described in literature. Especially, quantitation of adjacent substance zones was critical when improper combinations of these settings merge. Future trends regarding ultrathin-layer chromatography and hyphenation to scanning or imaging mass spectrometry required the consideration of these delicate points. The influence of different instrumental settings on the obtained signal intensities was demonstrated for four separated parabens (each 150 ng band−1). The maximum mean signal deviations of all four compounds were 6.9% by the optical system, 16.8% by the scan slit dimension, 7.5% by the scan speed, and 1.5% by the data resolution. The influence of these settings on the quantitation of three parabens in two skin protection creams was investigated. Depending on the selected settings, deviations of the calculated substance amount of up to 5.6% were yielded, whereby determination coefficients of the polynomial calibration curves (60–300 ng band−1) varied between 0.9985 and 0.9999. The setting of integration markers between two adjacent peaks was demonstrated to be deficient if low spatial data resolution is applied; however, this challenging task will rise in interest due to the trend towards miniaturization.

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This study investigated the chemical properties of Durio zibethinus (Durian) in Malaysia. The cultivars included in the present study were D101, D197, and Kampung. A wide range of chemical properties such as proximate nutritional content, minerals, total phenolic content was analysed using established analytical methods. The antioxidant capacity in term of free radical scavenging activity was determined using colorimetric assay, whereas metabolite profiles of samples were analysed by hyphenated high throughput tool like GC-MS. The results showed that D197 durian had the highest content of ash, protein, fat, and carbohydrate, but the lowest moisture level. Potassium was found to be the highest mineral (8.68–11.36 mg g–1), followed by sodium (3.2–7.6 mg g–1), magnesium (0.86–1.88 mg g–1), and calcium (2.74–3.80 mg g–1) in the tested cultivars. The major sulphur containing compounds (% relative peak area) such as hydrogen sulphide (5.0–8.3%), methanethiol (0.5–1.0%), ethanethiol (20.7–35.0%), 1-propanethiol (2.7– 9.5%), and diethyl disulphide (0.6–1.9%), and esters, especially ethyl 2-methylbutanoate (10.0–15.0%), methyl 2-methylbutanoate (1.0%), and propyl 2-methylbutanoate (1.5%) were detected when fresh samples were heated in headspace GC-MS. However, those compounds evaporated during ultrasound assisted extraction and oven drying even at 40 °C.

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JPC - Journal of Planar Chromatography - Modern TLC
Authors: Andrej Oriňák, Guido Vering, Heinrich Arlinghaus, Jan Andersson, Ladislav Halas, Renáta Oriňáková, and L’udmila Turčániová

A new hyphenated technique that enables coupling of thin-layer chromatography (TLC) with time-of-flight secondary-ion mass spectrometry (TOF-SIMS) has been used for identification of gibberellic acid, as model analyte. TOF-SIMS has outstanding capabilities for molecular surface analysis, trace metal determination on surfaces, and surface imaging. When TLC and TOF-SIMS are coupled on-line, the chromatographic thin layer must be modified to avoid TOF-SIMS background signal activity from the chromatographic material or solvents used. Two different types of TLC plate were used for coupling with TOF-SIMS. The first was an aluminum backed plate modified to form a universal porous TLC-TOF-SIMS coupling interface. The second was a commercially available plate with a monolithic silica layer. Low TOF-SIMS background signal intensity, surface homogeneity, and integral analyte transfer characterize this novel TLC-TOF-SIMS interface. TOF-SIMS images of the TLC surfaces with separated gibberellic acid were used for identification purposes. SIMS enables analyte detection with high mass resolution at a level of concentration not achieved by other methods. The system described can easily be coupled with dynamic microcolumn high-performance liquid chromatography (μHPLC).

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Journal of Thermal Analysis and Calorimetry
Authors: Vincent Janssens, Christophe Block, Guy Van Assche, Bruno Van Mele, and Peter Van Puyvelde

Abstract  

A newly developed hyphenated technique is presented that combines an existing rheometer and differential scanning calorimeter (DSC) into a single experimental setup. Through the development of a fixation accessory inside the cell of the calorimeter and the introduction of an add-on unit for the rheometer, the simultaneous calorimetric and rheological measurement inside the well-controlled thermal environment of a Tzero™ DSC cell opens new experimental possibilities. The evolution of thermal and flow properties of a material can be simultaneously monitored during steady or oscillatory shear flow and regular or modulated temperature DSC measurements. The technique offers interesting opportunities for the investigation of flow-induced transitions, such as crystallization or phase separation, and provides a possibility for high-throughput screening of materials. The signal quality of the novel technique in comparison to the stand-alone techniques is demonstrated by the evaluation of the calibration factors and by measurements on standard materials. Finally, combined rheological and calorimetric melting and crystallization experiments on polycaprolacton are performed.

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Abstract

Checking for the presence of egg in a painting layer allows to decide whether or not it is a tempera. Several already assessed analytical techniques may be used to perform the chemical analysis for the detection of egg in paintings. As an advantageous and alternative methodology for the determination of egg, a new application of analytical pyrolysis, hyphenated with gas chromatography–mass spectrometry (GC–MS) system, in presence of hexamethyldisilazane (HMDS) and tetramethylammonium-hydroxide (TMAH), is reported here. The innovation lays mainly in the choice of new markers for the presence of egg. It is here demonstrated that in art diagnostic tris-TMS-ester and methyl ester of phosphoric acid, generated by the pyrolysis of standard phospholipids and synthetic painting layers containing egg as binding medium, may be used as new markers for identification of egg in tempera layers. The adoption of these new markers in analytical pyrolysis allows to obtain higher analytical performance with respect to classical markers (fatty acids), especially in terms of yield and, as a consequence, in terms of limit of detection.

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The technological improvement in the structural elucidation of natural compounds has made it probable to generate appropriate strategies for the analysis and standardization of plant-based medicines. An appliance of highly oriented hyphenated techniques provides a definite tool for herbal investigations. Therefore, the present study was directed towards the standardization of biomarkers gallic acid and berberine in polyherbal formulation Entoban capsules to ensure the quality of the herbal drugs. A rapid, simple, accurate, and specific high-performance thin-layer chromatography (HPTLC) method for the quantitative estimation of biomarkers berberine and gallic acid has been developed. HPTLC was performed to evaluate the presence of gallic acid and berberine applying toulene—ethyl acetate—formic acid—methanol (12:9:4:0.5 v/v) and ethanol—water—formic acid (90:9:1 v/v), as the mobile phase, respectively. The R F values (0.58 for gallic acid and 0.76 for berberine) in both sample and reference standard were found comparable under ultraviolet (UV) light at 273 nm and 366 nm, respectively. The method developed resulted in good-quality peak shape and enabled high-quality resolution of biomarkers. The present standardization undertaken reveals compliance with the analytical procedure; therefore, it is concluded that Entoban capsule is a well-standardized product. Standardization falls under the specific guidelines of quality herbal medicine following the prerequisite for global harmonization.

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