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Summary

The merits of chemometrics in categorizing different Egyptian olive chemovarieties based on their compositional integrity were implemented in this study. Fingerprints of 9 different olive leaves varieties cultivated in Egypt were established using reversed-phase high-performance thin-layer chromatography (RP-HPTLC) prior to and after post-chromatographic derivatization with natural product-polyethylene glycol (NP/PEG) reagent and image analysis using ImageJ® software in order to build 2 separate data matrices. The chromatographic fingerprints were separately subjected to unsupervised pattern recognition multivariate analysis to build 2 separate models using principal component analysis (PCA) and hierarchical clustering analysis (HCA) algorithms to explore the distribution pattern of different chemovarieties. The second model which involved olive samples’ fingerprints after post-chromatographic derivatization exhibited greater ability to reveal a broader spectrum of phytoconstituents with enhanced sensitivity. Densitometric RP-HPTLC quantification of oleuropein marker was compared to image analysis approach using Sorbfil TLC Videodensitometer® by newly developed and validated methods. Densitometry exhibited better performance characteristics than image analysis method and therefore was executed for determination of oleuropein concentration in the 9 Egyptian olive varieties. Oleuropein marker solely was found to be inadequate for standardization of olive leaves varieties. This study demonstrated a comprehensive approach for the rapid classification of different Egyptian olive varieties, which is crucial to warranting their chemical-consistency and, thereafter, effective consistency.

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The objective of this study was to explore the possibility of combining headspace gas chromatography with mass spectrometric detection (HS-GC-MS) and 13C NMR spectroscopy to enhance the detectability of components of the essential oils of medicinal plants of the Salvia genus. Preliminary investigations were performed with two sage species, Salvia lavandulifolia and Salvia triloba, known for particularly abundant yields of their respective essential oils. By use of HS-GC-MS, characteristic fingerprints of the volatile fractions were obtained for plant species from two different vegetation seasons (2007 and 2008). Partial identification of the components of these volatile fractions was performed, and comparison of the chromatographic fingerprints confirmed seasonal fingerprint similarity within the same species. Preliminary 13C NMR measurements resulted in well shaped spectra with an abundance of regularly distributed signals. This suggested the possibility of using 13C NMR spectroscopy in phytochemical research, in parallel with HS-GC-MS, to enhance the detectability of volatile components of plant species belonging to this genus.

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Abstract  

Obsidian samples from the Tokaj Mountains (Hungary) and from the neighbouring Zemplin Hills (Slovakia) were analysed by instrumental and epithermal neutron activation analysis for obtaining a “fingerprint” for discrimination of potential natural sources of raw material that would permit tracing the origin of archaeological obsidian artefacts. These techniques fully discriminate the Zemplin Hills sources (Carpathian I, eastern Slovakia) and the Tokaj Mountain sources (Carpathian II, north-eastern Hungary) as well as these Central European sources from those already studied of the Mediterranean basin and adjacent regions.

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Abstract  

INAA results obtained on 11 vegetal samples proposed as European reference standards, in nutritional, agricultural and analytical studies are reported. A comparison is also reported with the data obtained by 38 European laboratories, by using spectrochemical methods (ICP atomic absorption, X-ray fluorescence, etc.). The usefulness of Instrumental Neutron Activation Analysis (INAA) is stressed, particularly when more usual methods are not sensitive enough for microelements that are important markers of toxic and pollutant substances. To this class belong lanthanides and other rare elements (Sc, Cs, Rb), which can be used both as fingerprint of soil provenance and for evaluating the homogeneity of the sample.

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This study discussed the phenomena on thermal polymerization of α-methylstyrene (AMS). A curve scanned by temperature-programmed technique was performed by differential scanning calorimetry (DSC). Heat of polymerization (ΔH) and onset temperature of exothermic (T 0) behavior were determined to be 28010 J g-1 and about 1381C, respectively. A dimer formation mechanism was proposed for initiation of the propagating chain. Spectroscopic identification of dimer structure was conducted by infrared (IR) spectroscopy in the wavenumber from 650 to 1100 cm-1associated with molecular fingerprint characteristics. The mechanism of thermal polymerization on α-methylstyrene proposed in this study was similar to that of styrene suggested by Mayo.

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The crude methanolic extracts of a single bean from samples of organic, natural or genetically modified (GM) soybeans [Glycine max. (Merrill) L.] were analyzed by direct infusion electrospray ionization mass spectrometry (ESI-MS). These extracts, containing the most polar natural products of soybeans (free aglycones, monoglucosides, diglucosides and esters including isoflavones and flavones) provide characteristic fingerprinting mass spectra owing to different proportions or sets of components. Spectra distinctiveness is confirmed by chemometric multivariate analysis of the ESI-MS data, which place the three-types of beans into well-defined groups. When ESI-MS is applied, these polar components constitute therefore unique chemotaxonomic markers able to provide fast soybean typification.

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Chemometric assessment of thermal oxidation of some edible oils

Effect of hot plate heating and microwave heating on physicochemical properties

Journal of Thermal Analysis and Calorimetry
Authors: M. Khan, Anila Sarwar, and M. Wahab

Abstract  

The effect of microwave heating was studied in six varieties of edible oil. Variations in physicochemical properties were observed and compared with the data obtained by hot plate heating. Fourier-transform infrared spectra of the oils showed substantial variations after both types of heating in the region of hydrogen’s stretching (C–H) vibration, region of double bond’s stretching (C=O), and fingerprint region. The visible spectra of mustard and olive oil showed the reduction in carotenoid, flavonoid, and chlorophyll pigments after heating. The oil samples were discriminated as saturated, monounsaturated, and polyunsaturated fats using chemometric techniques on physical and spectroscopic measurements.

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A set of 35 uranium ore and 10 yellow cake samples, collected worldwide from different mines and production sites, were analyzed for their impurity spectrum by ICP-MS. Pattern recognition techniques such as cluster analysis were applied to the data set in order to characterize samples with relation to their geographical origin. The results obtained show a clear relationship between samples taken from the same geological origin and constitute a satisfactory fingerprint for establishing the origin of the material. In addition to the impurity data, data on the isotopic composition of radiogenic lead is used to resolve ambiguity when impurity cluster analysis fails to deliver unambiguous origin data.

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Abstract  

Differential thermal analysis (DTA) was the first thermal analysis technique used to qualitatively characterize natural clays and respective curves has been used since more than 60 years as their ‘fingerprint’. With the development of microprocessed equipments in the last decades, derivative thermogravimetric (DTG) curves also may be used for this purpose in some cases, which also may allow a quantitative characterization of clay components. TG and DTG curves are more indicated than DTA or DSC curves to identify and to better analyze the several decomposition steps of natural or synthetic organoclays. These questions are discussed in applications developed to characterize Brazilian kaolinitic clays, bentonites and organophilic clays.

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JPC - Journal of Planar Chromatography - Modern TLC
Authors: Mieczysław Sajewicz, Łukasz Wojtal, Michał Hajnos, Monika Waksmundzka-Hajnos, and Teresa Kowalska

In a previous paper we discussed the possibility of fractionating the essential oils of different sage species by low-temperature preparative layer chromatography (PLC), followed by preparative isolation of the contents of each fraction and further analysis by GC-MS. In that way we attempted to emphasize the practical usefulness of lowtemperature planar chromatography for investigation of volatile compounds. In this study, we explore a possibility of fractionating essential oils contained in the different sage species by low-temperature analytical TLC followed by direct mass spectrometric analysis of the separated fractions. This objective can be achieved by TLC-MS with on-line transfer of the eluted fractions. The densitograms obtained from five different sage species (i.e., S. lavandulifolia, S. staminea, S. hians, S. triloba , and S. nemorosa ) are compared. Each densitogram is accompanied by mass spectra recorded for each peak. Videoscans of the chromatograms are also presented. In this way multiple fingerprints of the analyzed plant material, each comprising a densitogram and a selection of mass spectra, were obtained. Advanced chemometric treatment of these multiple fingerprints can be used to reveal statistically significant differences between the plant species. Analytical and chemotaxonomic advantages and further aspects for this kind of approach are discussed.

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