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81.
Łukasz Woźniak Krystian Marszałek Sylwia Skąpska Renata Jędrzejczak 《Chromatographia》2017,80(10):1527-1533
Triterpenic acids are a group of secondary plant metabolites which are part of the cuticular waxes covering fruits, leaves, and flowers. To date, quantitative analysis of these compounds has often been conducted using high-performance liquid chromatography coupled with spectrophotometric detection or mass spectrometry; however, these methods have some major drawbacks. This paper reports a new method of analysis implementing derivatization with 9-anthryldiazomethane and fluorescence detection. The method consists of the extraction of analytes from a matrix, purification with anion exchanging SPE columns, and an optional step of the alkaline hydrolysis of triterpenic acid esters. The paper also describes a fast and easy method for the synthesis of the derivatization agent. The detection limits of the method presented are approximately 100-fold lower than in a similar method using ultraviolet spectrophotometry as the mode of detection. The recovery and repeatability of the method are at satisfactory levels. 相似文献
82.
Sylvain Maclot Michael Capron Rémi Maisonny Arkadiusz Ławicki Dr. Alain Méry Dr. Jimmy Rangama Prof. Dr. Jean‐Yves Chesnel Sadia Bari Prof. Dr. Ronnie Hoekstra Dr. Thomas Schlathölter Prof. Dr. Bruno Manil Prof. Dr. Lamri Adoui Dr. Patrick Rousseau Prof. Dr. Bernd A. Huber 《Chemphyschem》2011,12(5):881-881
83.
84.
Grażyna Bartkowiak Elżbieta Wyrzykiewicz Grzegorz Schroeder Anna Walkowiak Anna Szponar Ilona Pawlak 《Phosphorus, sulfur, and silicon and the related elements》2013,188(7):1429-1436
Eighteen new 2,4-di-ortho- (meta- and para-) bromo-(chloro- and nitro-)benzylthio-5-bromouracils (and 6-methyluracils) have been prepared. The structures of these compounds were confirmed by spectral (IR, UV/vis, 1H NMR) and elemental analyses. Estimation of pharmacotherapeutic potential has been made for synthesized compounds on the basis of prediction of activity spectra for substances (PASS). 相似文献
85.
Robert Łysek Ewa Woźny Marek Chmielewski 《Phosphorus, sulfur, and silicon and the related elements》2013,188(2):327-340
Chiral formates derived from propane-1,2-diol, 1,2- O -isopropylidene- f - D -xylo- and f - D -gluco-furanoses were subjected to treatment with cyclopentadienyl [tris(trimethylsilylmethyl)] titanium (IV). A mixture of the corresponding ( E )- and ( Z )- g -silylvinyl ethers were obtained with predominance of the former. It was found that in contrast to ( Z )-vinyl ethers, which give g -lactams with chlorosulfonyl isocyanate, the ( E )-vinyl ethers gave unstable cycloadducts which undergo rapid elimination reaction leading to ( E )- f , g -unsaturated amides. 相似文献
86.
87.
Józef Drabowicz Piotr Łyżwa Jan Omelańczuk Marian Mikołajczyk 《Phosphorus, sulfur, and silicon and the related elements》2013,188(1)
Abstract The title compound optically active t-butylphenylphosphine oxide 1 is widely used as a key substrat for the synthesis of other optically active derivatives such as α-hydroxyphosphine oxides, vinylphosphine oxides Till now, it has been obtained by a few rather laborious procedures1 相似文献
88.
Bogumił Łaszkiewicz 《高分子科学杂志,A辑:纯化学与应用化学》2013,50(2):421-432
The reaction mechanism of phosphorous acid and poly(vinyl alcohol) is presented. It has been found that there during this reaction mono- and diesters are formed in which most of the acid radicals are in the phosphonic form. To confirm the presence of this form in the product obtained, reactions with diethyleneamine and chloral have been carried out as characteristic tests for phosphonic groups. The occurrence of C—P bonds resistant to hydrolysis has been also found in the reaction product. 相似文献
89.
D. F. Parra P. L. Forster R. Łyszczek A. Ostasz A. B. Lugao Z. Rzączyńska 《Journal of Thermal Analysis and Calorimetry》2013,114(3):1049-1056
The aim of this study has been to gain a fundamental understanding of the mechanisms governing thermal degradation of luminescent poly(3-hydroxybutyrate) (PHB). PHB was doped with diaquatris(thenoyltrifluoroacetonate) europium(III) complex, [Eu(tta)3(H2O)2], and different luminescent systems were obtained. The thermal-stability of the luminescent films was discussed and the products of decomposition were analyzed. Thermal degradation of PHB:Eu(tta)3 x % systems (x = 0, 1, 5, 10, and 15 %) was elucidated by means of thermogravimetric analysis (TG), the thermal-stability decreases with the increase of europium complex concentration. The PHB polymer decomposed with evolution of carbon dioxide and 2-butenoic acid molecules. The TG–FTIR results, of the gaseous degradation products of PHB in nitrogen atmosphere, indicated that the polymer is stable at temperatures up to 200 °C. Polymer matrix at concentrations above 5 % decomposed with evolution of water molecules among the other gaseous products, which implied the presence of a hydrated complex in the system. The luminescent films showed more flexibility due to a loss in crystallinity, which suggested a potential usefulness in technical applications. 相似文献
90.
Grzegorz Skrzypek 《Analytical and bioanalytical chemistry》2013,405(9):2815-2823
The uncertainties of stable isotope results depend not only on the technical aspects of measurements, but also on how raw data are normalized to one of the international isotope scales. The inconsistency in the normalization methods used and in the selection of standards may lead to substantial differences in the results obtained. Therefore, unification of the data processing protocols employed is highly desirable. The best performing methods are two-point or multipoint normalization methods based on linear regression. Linear regression is most robust when based on standards that cover the entire range of δ values typically observed in nature, regardless of the δ values of the samples analysed. The uncertainty can be reduced by 50 % if measurements of two different standards are performed four times, or measurements of four standards are performed twice, with each batch of samples. Chemical matrix matching between standards and samples seems to be critical for δ 18O of nitrate or δ 2H of hair samples (thermal conversion/elemental analyser), for example; however, it is not necessarily always critical for all types of samples and techniques (e.g. not for most δ 15N and δ 13C elemental analyser analyses). To ensure that all published data can be recalculated, if δ values of standards or the isotope scales are to be updated, the details of the normalization technique and the δ values of the standards used should always be clearly reported. 相似文献