Search Results
The use of thin-layer chromatography (TLC) for separation, identification and quantification of different organic and inorganic substances is limited by the visualization of the separated and determined substances. In literature, there are innumerable references which present chemical, physical and biological methods of visualization of different kinds of organic and inorganic substances, especially the ones which do not absorb visible light. However, scientists are looking for new, more efficient reagents for a selective visualization of the definite part of a substance or, in some cases, for a specific determination of specific substances. This article describes a different method of visualization of the substances separated on the TLC plates. Special attention was paid to the different chemical reaction applied to obtain colour substrates of the reaction between separated substances and the property of the chosen derivate reagents. Describing different methods of visualization we tried to compare different groups of the determined substance, using different methods of their visualization. The analysis shows, for the first time, that different types of substances need different types of reactions and different types of reagents. The results of the TLC detection of the broad spectrum of the representative classes of organic derivatives are presented in table. The data illustrate the possibilities of TLC differentiation of the organic compounds which contain different active groups. The most unusual effect was obtained during the TLC application of the induced detection reagent. As a matter of fact, some sulphur atoms in their molecules are able to induce the iodine-azide reaction.
Salicylic acid and its derivatives, such as acetylsalicylic acid, are commonly used non-steroidal anti-inflammatory agents. In the present work, different sorbents as the stationary phases and also various manners of detection using well known and new visualizing reagents have been tested for the separation and detection of the two compounds by adsorption and also partition thin-layer chromatography (TLC) with densitometry. Densitometric and spectrodensitometric analysis was used to evaluate the detectability of the examined compounds using the newly developed TLC procedures. Of all the applied manners of detection, the most universal to distinguish acetylsalicylic acid from salicylic acid in normal- as well as in reversed-phase TLC system is the use of methanolic solution of FeCl3 and CoCl2. The densitograms obtained under these conditions show symmetric and also by adsorption well separated TLC peaks of both compounds. The shape of all absorption bands of acetylsalicylic acid (ASA) and 2-hydroxybenzoic acid (SA) recorded using a scanning densitometer in the range of 200–700 nm is regular. In the case of adsorption TLC performed on chromatographic plates precoated with silica gel 60 F254 and silica gel 60, a very effective spray reagent was also Janus blue. The satisfactory results of detection on silica gel 60 plates assure the use of 1% NaOH as spray reagent followed by heating at 90°C for 60 min. The results performed in the present work confirm the utility of TLC in combination with densitometry in the qualitative screening and identification of SA and ASA. The most efficient manners of detection described in this work can be helpful in the quality control of acetylsalicylic acid, e.g., in monitoring the synthesis reaction of acetylsalicylic acid from salicylic acid as well as in the quality control of ASA in commercially available products.
: Grundlagen, Reagenzien I, VCH, Weinheim , 1989 . [5] H . Jork , W . Funk , W . Fischer , and H . Wimmer , Thin-Layer Chromatography: Reagents and Detection Methods, Vol. 1b, Physical and Chemical Detection Methods: Activation Reactions, Reagent
Introduction Research topics such as community detection and topic identification are becoming appealing in bibliometrics. Essentially, these two topics are not new to bibliometricians. On one hand, methods such as hierarchical
approach to edge detection , IEEE Trans. Pattern Anal. Mach. Intell , Vol. 8 , No. 6 , 1986 , pp. 679 ‒ 698 . [17] Bölkény I. , Füvesi V
Brunt, J.W. and W. Conley. 1990. Behaviour of a multivariate algorithm for ecological edge detection. Ecol. Model. 49:179-203. Behaviour of a multivariate algorithm for ecological edge
M. Ranny , Thin Layer Chromatography with Flame-ionization detection, Riedel, Dordrecht, 1987. Ranny M. Thin Layer Chromatography with Flame
capability of being touched off either by another open fire in the area or by its own temperature. This leads to impacts like fiery surge and discharge [ 1 ]. The current procedures for smoke detection include the utilization of some type of hardware and this
227 Chang, S. & Kang, D. (2004): Alicyclobacillus spp. in the fruit juice industry: history, characteristics, and current isolation/detection procedures. Crit. Rev
