Clean-up of matrix-rich samples using high-troughput planar solid phase extraction (HTpSPE). Black and green tea samples were spiked with 7 pesticides (acetamiprid, azoxystrobin, chlorpyrifos, fenarimol, mepanipyrim, penconazole, and primicarb) at level 0.01, 0.1 and 1 mg/kg. Extraction with acetonitrile, pre-cleaning by dispersive SPE. TLC on silica gel (prewashed with acetonitrile) of samples applied as rectangles of 3 x 16 mm first with acetonitrile - water 19:1 over 85 mm and after drying for 5 min with acetone - water 7:1 in the opposite direction over 31 mm. Detection under UV 254 and 366 nm and by dipping in primuline reagent (0.2 % in acetone - water 4:1) and detection under UV 366 nm and white light. Elution of target zones into autosampler vials by TLC-MS Interface with acetonitrile - 10 mM ammonium formate buffer 1:1, flow rate 0.2 mL/min. After clean-up the samples are free of caffeine which interferes with pesticide detection.

Proc. 6th Int. Symp. Instrum. Planar Chromatogr., (Interlaken 1991), Inst. Chromatogr., Bad Dürkheim, FRG, 231-234 (1991). The sample preparation system includes an OPLC chamber as an interface where samples of interest are migrated toward the column of an HPLC system. Another way of clean-up is the combination of conventional TLC with OPLC transfer. According to the chromatographic properties of unwanted sample materials, the impurities in front and/or starting zone can be eliminated while analyzable compounds from the localized area of the layer can be transferred to the HPLC system.

J. Chromatogr. A 1217 (23), 4655-4662 (2010). Development and application of electrospun glassy carbon nanofibers for ultra-thin layer chromatography (UTLC). The carbon nanofiber stationary phase was created through electrospinning and pyrolysis of SU-8 2100 photoresist, which resulted in glassy carbon nanofibers with diameters of 200-350 nm that form a mat structure with a thickness of 15 µm. The chromatographic properties of UTLC devices produced from pyrolyzed SU-8 heated to temperatures of 600, 800, and 1000 °C were investigated. By use of Raman spectroscopy and scanning electron microscopy the physical and molecular structure of the nanofibers at each temperature was determined. The carbon UTLC devices were suitable for the analysis various dye mixtures and also allowed separation of three FITC-labeled essential amino acids (lysine, threonine, phenylalanine). The electrospun glassy carbon UTLC plates showed good retention properties, plate number values above 10000, and physical and chemical robustness for a range of mobile phases.

J. Planar Chromatogr. 29, 45-58 (2016). Vertical chamber dielectrochromatography (V-LDEC) of two lipophilic dyes, Sudan blue (1) and Sudan II (2) on plates containing increasing amounts (1, 2, 3, 4, 6, 8, 10) g of barium titanate in 35 g alumina with toluene – n-hexane 1:1. The periods of maintaining the electric field consisted of 3 cycles, one cycle of about 17 min. The voltage between the armatures for each experiment was maintained at 3 kV AC value. Improved separations were obtained for the ratios of 2:35 and 3:35 (g/g) barium titanate – alumina both in equicurrent and mostly in countercurrent.

J. High Resol. Chromatogr. 8, 44-45 (1985). TLC of glycyrrhetinic acid on HPTLC silica, treated with 0.7 % benzene solution of 3-APTS, with butanol - NH3 - ethanol 5:2:1. Detection by UV. In situ densitometry. Detection limit 50 ng.

J. Agric. Food Chem. 34, 89-92 (1986). TLC of (14 C) chlorsulfuron (2-chloro-x-(((4-methoxy-6-methyl-1,3,5-triazine-2-yl) amino) carbonyl) benzenesulfonamide) on plates coated with different soils; 0.01 N CaCl2 solution as eluent. Detection by autoradiography.

J. Planar Chromatogr. 1, 235-238 (1988). Description of a-chitin as stationary phase for TLC. Investigation of its chromatographic properties in separation of amino acids and dyes. Discussion of some of its advantages.

Chromatographia 26, 145-148 (1988). Study of TLC retention and selectivity behavior of bufadienolides on phenyl-modified silica with various methyl cyanide - water or methanol - water mixtures. Discussion of the selectivity of the systems for the separation of cinobufagin, vesibufogenin and bufalin.