(HP)TLC is a technique with large applicability in the fields of plant material analysis and stability tests of extracts and finished products. The implementation of a modern standardized methodology led to the increasing of acceptance and recognition of (HP)TLC as competitive analytical method. (HP)TLC has many advantages, such as lower costs, short time analysis, the possibility of multiple detection, and specific derivatization on the same plate, etc. The natural antioxidants (polyphenols) are present in plant extracts; they play a key role in antioxidative defence mechanisms in biological systems and they act as free radicals scavenging agents. The separation of polyphenols from each other and from other components of the plant extracts can be done by a great number of (HP)TLC developed techniques. Mostly, complex crude plant extracts are screened for antioxidant activity or to distinguish the components of plant extracts with antioxidant character or radical‐scavenging properties. (HP)TLC has been used for the determination of individual antioxidant capacity of target compounds and it might be of interest to the routine chemical or biological screening and they can solve real analytical problems.

Brassica oleracea L. var. Italica is known to contain a wide variety of antioxidants and due to the protection against various diseases its consumption has been increasing over the years. Thus, knowledge of the changes that occur during the digestion process is of great interest. The aim of this study was to investigate the influence of in vitro gastrointestinal digestion of broccoli on antioxidant activity and on the chlorophyll, carotenoid and phenolic content. First, the ultrasound-assisted extraction of bioactive compounds was optimized and the kinetic model was evaluated. Then, the broccoli was subjected to a static simulated digestion. The antioxidant activity was monitored by ABTS [2,2’-azinobis-(3-ethylbenzothiazoline-6-sulfonate)] assay and the contents of target compounds were investigated by UV-Vis spectrophotometry and thin-layer chromatography. The optimum conditions were: solvent—ethanol; time—20 min and temperature—30 °C, and a second order kinetic model was found to describe the mechanism of extraction. The antioxidant activity and carotenoid, chlorophyll and total phenolic content was significantly decreased after simulated gastric and intestinal digestion. The gastric digestion considerably decreased carotenoid and chlorophyll content, meanwhile the intestinal digestion significantly decreased the total phenolic content (TPC). The antioxidant activity was equally affected by both gastric and intestinal digestion.

Vitamins are compounds with biological activity and they are essential and fundamental for normal health and organisms growth. Vitamins are available in diet and supplements and their deficiency can lead to some human diseases. The analysis of these compounds is indispensable for monitoring their content in pharmaceuticals and food in order to prevent some human diseases. Thin layer chromatography (TLC) is generally regarded as a common analytical method for screening, separation, and preliminary identification of compounds. TLC plays an important role in the quality control of food and drugs in order to investigate the ingredients and to detect the impurities and also for checking the purity and the stability of preparations.

Hydrophilic vitamins play an important role in human health. The analysis of these compounds is indispensable for monitoring their content in pharmaceuticals and food in order to prevent some human diseases. The separation and identification of eight hydrophilic vitamins, i.e., B₁, B₂, B₃, B₅, B₆, B₉, B₁₂, and C, was achieved by thin layer chromatography and Raman spectrometry. After chromatographic experiments, the best results were obtained using programmed multiple development. The unambiguous identification of superimposed spots can be done without using standards of vitamins.