Thin-layer chromatography of hydroxyanthraquinones in plant extracts

Summary Existing thin-layer chromatographic (TLC) methods for the separation of hydroxyanthraquinones in plant materials were found to have limited applications. This initiated the development of some new TLC systems to separate the five principal hydroxyanthraquinones: chrysophanol, physcion, emodin, rhein and aloe emodin normally present together in plant materials, on a single chromatogram and usually with a single solvent system.     

Thin-layer chromatography in spices analysis

Spices are the dried parts of aromatic plants, excepting the leaves, usually used for flavoring, seasoning and imparting aroma in foods. They contain many classes of valuable compounds, which can also exert different biological activities, such as antioxidant and antimicrobial activity. Since spices contain important bioconstituents, they are often adulterated in economical purposes, not only by the botanical and geographical origin, but also by adding or subtracting of different substances which affect in a negative manner their quality. The aim of this paper is to overview the TLC methods used in the analysis of spices, in order to evaluate their composition and biological activities, and also to detect the adulteration.     

Predicting retention data in gas-liquid chromatography by multivariate analysis

Satisfactory reproduction of the retention data matrix in the case of a series of mono-substituted benzenes and a series of aliphatic substances proves the general character of the prediction equation

where x_Qi, φ_j are the retention data x of unknown solute Q_i on phase φ_j; a_Qi, b_Qi, c_Qi and d_Qi are regression coefficients which to some extent account for forces of orientation, charge transfer and association; and x_STi, φ_j are independent variables representing the retention data of the four compounds of the standard set of substances on a given phase φ_j. These four compounds are selected by diverse methods of multivariate analysis. The predicted values show very satisfactory agreement with the observed values.     

Thin-layer chromatography in food and agricultural analysis

The TLC analysis of agricultural products, foods, beverages, and plant constituents is reviewed for the period from mid-1995 to mid-1999. Techniques and applications for a wide range of analyte and sample matrix types are covered, with specification of the particular layers, mobile phases, detection methods, and quantification conditions in many cases.     

Thin-layer chromatography in the analysis of sunscreens

Thin-layer chromatography is a convenient analytical tool for the analysis of sunscreen containing products. This paper covers the details of performing the essential steps in the analysis of both synthetic and natural sunscreens. References to current and past key papers are cited with examples of these sunscreens and updates of advances in tools and techniques to make this an even more important analytical technique.     

Thin-layer chromatography of mycotoxins

TLC has become an extremely powerful, rapid and in most instances inexpensive separation technique in mycotoxicology. This review presents achievements of its applications in this field. General technical aspects of the TLC of mycotoxins that are discussed include extraction and clean-up procedures, adsorbents and solvent systems, detection methods, two-dimensional TLC, high-performance TLC (HPTLC), quantitation and preparative TLC (PLC). Special applications of TLC deal with multi-mycotoxin analyses and with structurally related or individual mycotoxins (aflatoxins, sterigmatocystins, versicolorins, ochratoxins, rubratoxins, patulin, penicillic acid, mycophenolic acid, butenolide, citreoviridin, trichothecenes, cytochalasans, tremorgenic toxins, epipolythiopiperazine-3,6-diones, hydroxyanthraquinones, zearalenone, citrinin, secalonic acids, cyclopiazonic acid, PR toxin, roquefortine, xanthomegnin, viomellein and naphtho-gamma-pyrones).