Micro 2D-TLC of Selected Plant Extracts in Screening of Their Composition and Antioxidative Properties.

Micro two-dimensional separations were performed on polar bonded stationary phases of the type cyanopropyl-silica using non-aqueous eluents (polar modifier dissolved in n-heptane) as the first direction eluents and aqueous eluents (organic modifier-MeOH dissolved in water) as the second direction eluents. The chromatographic process was performed in micro scale using 5 × 5 cm plates, small volumes of eluents and 10 μL of plant extracts to obtain satisfying separation. Plates developed in horizontal chambers were dried and observed in UV light (254 nm and 366 m) photographed by digital camera and derivatized by DPPH to detect antioxidants (free radical scavengers) or derivatized by Naturstoff reagent to detect phenolic compounds (characteristic luminescence of some phenolic compounds). The above experiments give the possibility to construct fingerprints for investigated Polygonum hydropiper, Betula verrucosa and Pulmonaria officinalis extracts. It can be used in quality control of the plant material and its antioxidative activity. Novelty of the paper is the micro-scale of the separation by two-dimensional thin layer chromatography mode. For the first time two-dimensional separation of plant extracts on 5 × 5 cm plates in two directions is performed.