J. Planar Chromatogr. 25, 368-373 (2012). HPTLC of rebamipide on silica gel with toluene - methanol - triethylamine 16:9:1. Quantitative determination by absorbance measurement at 230 nm. The hRf of rebamipide was 59. Linearity was in the range of 100-600 ng/band. Limits of detection and quantification were 6 and 18 ng/band, respectively. Intermediate intra-day/inter-day precision was below 1.7 % (n=3). Recovery (by standard addition) was between 100.1 and 100.9 %. The proposed HPTLC method is equivalent to a reported HPLC method.

J. Liq. Chromatogr. Relat. Technol. 36, 167-179 (2013). HPTLC of darunavir in rat plasma on silica gel with toluene - acetone - methanol 3:1:1. Quantitative determination by mass spectrometry in the ESI+ mode and absorbance measurement at 254 nm. The hRf value of darunavir was 53. Linearity was in the range of 5-150 ng/µL. LOD and LOQ were found to be 1.2 and 3.9 ng/µL, respectively. Intermediate precision was below 2.7 %. Recovery (by standard addition) was 94.8-98.4 %. The recovery of the drug is improved compared with the HPLC method (96.7 %).

CBS 111, 13-15 (2013). HPTLC of propolis on silica gel in a twin trough chamber with 8 mL of n-hexane – ethyl acetate – glacial acetic acid 5:3:1 and preconditioning with 5 mL hydrochloric acid (37 %) in the opposite trough using filter paper wetted with the hydrochloric acid shortly before chromatography. Migration distance was 65 mm. Detection under UV 366 nm after dipping in 0.5 % methanolic 2-aminoethyldiphenylborane reagent followed by drying and dipping in 5 % methanolic polyethylene glycol solution. Different types of German propolis were found, an orange, a blue and mixed types. Comparison with HPTLC fingerprints of the possible origin plants showed that the orange type most likely derives from Populus nigra. The blue type correlated to a certain extent with Populus tremula as well as both types with Aesculus hippocastanum L. Confirmed by MS the following substances were found in the orange type: pinocembrin, galangin, caffeic acid phenethylester and chrysin. The blue type contained p-cumaric acid and ellagic acid. Caffeic acid, quercetin and apigenin appeared in both types.

J. Planar Chromatogr. 28, 144-151 (2015). TLC of L-cysteine on cellulose phase with 2-butanol - pyridine - glacial acetic acid - water 5:10:3:12. Just before development an equimolar amount of (1) manganese(II) acetate or (2) zinc(II) nitrate was added to the sample solutions. Detection in reflectance mode at 485 nm, concentration of L-cysteine and DL-cysteine in 70 % aqueous acetonitrile was 0.7 mg/mL. Developing distance was 7 cm, development time ca. 3 h. Derivatization by spraying with 0.5 % ninhydrin solution in 2-propanol, followed by heating for 5 min at 110 °C. The experiments demonstrate the spontaneous chiral conversion and spontaneous peptidization of L-cysteine, and the enantioseparation of L-cys and D-cys enantiomers is facilitated by chelating the transition metal cation (e.g. Mn(II)) with the cys ligands.

J. Chromatogr. A 1558, 77-84 (2018). Investigation of the influence of concentration of ion-pairing additive, as well as concentration and type of organic modifier of the mobile phase on migration of peptides in a pressurized planar electrochromatography (PPEC) system with octadecyl silica-based adsorbent. Comparison of the results with those obtained by similar HPTLC and PPEC systems. Discussion of the influence of particular variables on retention, electrophoretic mobility of solutes and electroosmotic flow of the mobile phase, of the co-influence of these factors on the final selectivity of peptide separation, and of the difficulty of independent optimization of these factors due to their impact simultaneously on the retention, the electrophoretic mobility, and the electroosmotic flow. The pH of the mobile phase was the main variable for optimization of the PPEC system. Extensive tailing of peptide zones in the PPEC was observed in comparison to similar HPTLC systems.

Anal. Chem. 56, 1035-1037 (1984). Improved detection system suitable for DEAE-cellulose in formic acid media. The new reagent is 1 or 2 orders of magnitude more sensitive than Ni(II)-DMG depending on the type of chelants. The 7 chelants identified were iminodiacetic acid, nitrilotriacetic acid, N-hydroxy-ethylenediamine-N,N',N-triacetic acid, ethylenediamimetetraacetic acid, (glycol ether) diamine-N,N,N',N'-tetraacetic acid, trans-1,2-cyclo-hexanediamine-N,N,N',N-tetraacetic acid, and diethylene-triamine-N,N,N',N-pentaacetic acid.

of Pharm.(Yaoxue Xuebao) 20, 59-66 (1985). (Chinese). (HPLC and TLC determination of alkaloid constituents in sophara flavescens and saphora lopecuroides.) TLC of sophocarpine, matrine, sophoridine, oxymatrine and oxysophocarpine on silica with benzene - acetone - methanol 8:3:0.5. Determination by densitometry at 510 nm. Comparison with HPLC results (good agreement).

Detection limit 300 -1000 ng for BHA, BHT and PG, resp. Also GC.