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In this short communication we report optimized procedures for the chiral separation of non-charged [6]helicene (1) and cationic derivative 1-butyl-3-(2-methyl[6]helicenyl)-imidazolium bromide (2) using high-performance liquid chromatography (HPLC) and supercritical fluid chromatography (SFC) methods. The possibility of using capillary electrophoresis (CE) was also tested. The satisfactory results were obtained with SFC, where the highly selective resolution of four enantiopure 1 and 2 helicenes was achieved in a single run within 5min. The semi-preparative procedure for the isolation of P and M enantiomers of compound 2, including circular dichroism data, is reported here for the first time. The results could be used in further separations and analytical applications targeting carbohelicenes vs. positively charged helicene derivatives., (Copyright © 2016 Elsevier B.V. All rights reserved.)

A fast determination of isoflavones (genistin, genistein, daidzein, daidzin, glycitin, glycitein, ononin, formononetin, sissotrin and biochanin A) by HPLC/UV-vis-DAD working at 254 nm is described. An Atlantis dC18 fast reversed-phase chromatographic column (20 mm x 2.1 mm, 3 microm particle size) was used at a flow rate 0.35 ml min(-1) of a mobile phase consisted from 0.1% (v/v) acetic acid (A) at pH 3.75 and methanol. (B). A linear gradient profile was used for separation at the column temperature 36 degrees C. Limits of detection (LODs for 3 S/N criterion) per sample injection (5 microl) ranged from 166.2 to 17.0 fmol (9.4-1.1 ng ml(-1) for biochanin A and genistin, respectively. The recoveries 96-106% were obtained for the different concentrations of the isoflavones (RSDs 2-8%). The pressurized liquid extraction/HPLC/UV-vis-DAD method was used for the determination of the isoflavones in soy bits (28-962 microg g(-1) dry weight). The proposed procedure is faster (ca. 8 min) without loosing its separation efficiency (up to 10 isoflavonoids can be determined) and sensitivity (tens to hundreds fmol).

Thiol compounds such as cysteine (Cys), reduced (GSH) and oxidized (GSSG) gluathione, and phytochelatins (PCs) play an important role in heavy metal detoxification in plants. These thiols are biological active compounds whose function is elimination of oxidative stress in plant cells. The aim of our work was to optimise sensitive and rapid method of high-performance liquid chromatography coupled with electrochemical detector (HPLC-ED) for determination of the abovementioned thiol compounds in maize (Zea mays L.) kernels. New approach for evaluation of HPLC-ED parameters is described. The most suitable isocratic mobile phase for the separation and detection of Cys, GSH, GSSG and PC2 consisted of methanol (MeOH) and trifluoroacetic acid (TFA). In addition, the influence of concentrations of TFA and ratio of MeOH:TFA on chromatographic separation and detection of the thiol compounds were studied. The mobile phase consisting from methanol and 0.05% (v/v) TFA in ratio 97:3 (%; v/v) was found the most suitable for the thiol compounds determination. Optimal flow rate of the mobile phase was 0.18 ml min(-1) and the column and detector temperature 35 degrees C. Hydrodynamic voltammograms of all studied compounds was obtained due to the selection of the most effective working electrodes potentials. Two most effective detection potentials were selected: 780 mV for the GSSG and PC2 and 680 mV for determination of Cys and GSH. The optimised HPLC-ED method was capable to determine femtomole levels of studied compounds. The detection limits (3 S/N) of the studied thiol compounds were for cysteine 112.8 fmol, GSH 63.5 fmol, GSSG 112.2 fmol and PC2 2.53 pmol per injection (5 microl). The optimised HPLC-ED method was applied to study of the influence of different cadmium concentrations (0, 10 and 100 microM Cd) on content of Cys, GSH, GSSG and PC2 in maize kernels. According to the increasing time of Cd treatment, content of GSH, GSSG and PC2 in maize kernels increased but content of Cys decreased. Decreasing Cys concentration probably relates with the increasing GSH and phytochelatins synthesis.