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  • Author or Editor: Małgorzata Dołowy x
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The bile acids cholic acid (C), glycocholic acid (GC), glycodeoxycholic acid (GDC), chenodeoxycholic acid (CDC), deoxycholic acid (DC), lithocholic acid (LC), and glycolithocholic acid (GLC) have been studied. Topological indices based on the adjacency matrix ( Gutman ( M v ), Randić ( 0 χ v , 1 χ v , and 2 χ v ), and Pyka ( χ 012 )) and on the distance matrix ( Wiener ( W ) and Pyka ( A , 0 B , 1 B , and C )), and electrotopological states (SdO (acid) , SsOH (acid) , and SsOH (aliph) ) were calculated. It was found that lipophilicity determined chromatographically ( R MW and ϕ 0 ), theoretical values ( A log P s , IA log P , C log P , log P KOWIN , x log P , and log P Rekker ), and experimental values determined by the classical method (log P exp ) correlated best with topological indices M v and C .

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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.

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The aim of the work was the chromatographic separation of salicylic acid and their derivatives, i.e., acetylsalicylic acid, salicylanilide, salicylaldehyde, salicylamide, methyl salicylate, phenyl salicylate, 2,5-dihydroxybenzoic acid, salicylhydroxamic acid, 3,5-dinitrosalicylic acid, 3-aminosalicylic acid, 4-aminosalicylic acid, and 5-aminosalicylic acid by use of adsorption thin-layer chromatography (normal-phase thin-layer chromatography [NPTLC]) and partition thin-layer chromatography (reversed-phase thin-layer chromatography/high-performance thin-layer chromatography [RP-TLC/HPTLC]). Three qualitatively and quantitatively different mobile phases were used for the separation of salicylic acid and its derivatives. Cluster analysis (single linkage method, Euclidean distance) allowed the evaluation of the suitability of the chromatographic conditions used to separate the pairs of tested compounds. The cluster analysis data indicate that the composition of the mobile phase is fundamental in the process of separation of the analyzed compounds by use of NP-TLC. The best separation of the studied substances was observed in the case of mobile phase n-hexane—diethyl ether—acetic acid (80%) in different volume ratios. The similarity analysis of the results obtained by use of RP-TLC/HPTLC revealed that the type of chromatographic plates influences significantly the quality of separation of the tested compounds. The best conditions for the separation by RP-TLC were obtained on silica gel RP-18 F254 plates. The present study indicates that the cluster analysis represents a simple-to-use and powerful chemometric tool in the prediction of TLC separation of medically important salicylic acid derivatives under various chromatographic conditions. It can be helpful in the quality control of multicomponent synthetic preparations containing these compounds or in the chemical standardization of plant products consisting of salicylic acid and related compounds.

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