J. Liq. Chromatogr. Relat. Technol. 31, 1977-1985 (2008). TLC of vitamin B 12 and dicyanocobinamide on silica gel with 2-propanol - 28 % ammonia - water 7:1:2 in the dark at room temperature. After drying the plate was overlaid with 1.5 % agar containing a basal medium and a small volume of E. coli 215 culture, and then incubated at 30 °C for about 20 h. After spraying with a methanolic solution of 4 % 2,3,5-triphenyltetrazolium salt the plate was heated at 30 °C for 1 h. The method was applied to detect vitamin B12 or inactive corrinoids in foods.

J. AOAC Int. 91, 1145-1148 (2008). TLC of alpha-mangostin on silica gel with dichloromethane - methanol 24:1 in a saturated twin-trough chamber. Quantitative determination by absorbance measurement at 320 nm.

Anal. Bioanal. Chem. 392, 849-860 (2008). HPTLC of cell lipids on silica gel with chloroform - ethanol - water - triethylamine 5:5:1:5. Detection under UV 366 nm after spraying with primuline (Direct Yellow) reagent. Coupling with MALDI-TOF-MS which is traditionally used for proteomics, but is also a useful tool for lipid analysis. Depending on the applied matrix, however, some lipid classes are more sensitively detected than others and this may even lead to suppression effects if complex mixtures are analyzed. Therefore, a previous separation into the individual lipid classes is necessary. Using artificial lipid mixtures or easily available tissue extracts, it has already been shown that lipids can be conveniently analyzed by MALDI-TOF MS directly on the TLC plate. An initial TLC-MALDI-TOF-MS study of the lipid composition of ovine mesenchymal stem cells is presented. Due to the complex composition of these cells, data are also compared to lipids extracted from human erythrocytes. Even very minor lipid classes can be easily detected and with much higher sensitivity than by common staining protocols.

Anal. Chem. 79, 8789-8795 (2007). TLC of dyes, amines, extracts of drug tablets (erythoxine B, erioglaucine, fast green FCF, 2,2’-diaminodiethylamine, 3-quinolinamine, 2-acetylaniline; tablets containing DL-methylephedrin hydrochloride, caffeine, ethoxybenzamide, chlorpheniramine maleate, noscapine, acetaminophen) on RP-18 with 500 mM ammonium acetate - acetone 7:3. Separation of amines on silica gel with ethyl acetate - acetic acid - dichloromethane 98:1:1. The detection limit of TLC/ELDI/MS is 1 µM.

Part I: Graft TLC of selected coumarins. J. Planar Chromatogr. 21, 237-241 (2008). HPTLC of coumarins (present in extracts of Archangelica officinalis, Pastinaca sativa and Heracleum sphondylium fruits) on cyano phase with acetonitrile - water 3:7 (triple development) in the first dimension, and on silica gel with ethyl acetate - n-heptane 7:13 (triple development) in the second dimension. Good selectivity differences were also obtained on silica gel with ethyl acetate - n-heptane 7:13 (triple development) in the first dimension and on RP-18 phase with methanol - water 11:9 (triple development) in the second dimension. Detection and quantitative determination by fluorescence measurement at 366 nm.

J. Planar Chromatogr. 21, 233-236 (2008). Connection of two-dimensional chromatography with multiple gradient development. 2D HPTLC of anthraquinone derivatives (1,8-dihydroxyanthraquinone, franguloemodin A, aloeemodin, rhein, frangulin A, aloin, sennoside B) on silica gel. Bandwise application at the right and left corner of the plate, then development by use of multiple gradient development [G. Matysik, Chromatographia 43, 39-41 (2004)], e.g. for step 1 hexane - dichloromethane 1:1, for step 2 (hexane - dichloromethane - ethyl acetate - 80 % formic acid 50:40:10:1) and for step 3 hexane - dichloromethane - ethyl acetate - methanol - formic acid 40:40:20:5:1. After drying the plate was developed from the left and right edge with hexane - dichloromethane - formic acid 60:40:1 for step 1 and with hexane - dichloromethane - ethyl acetate - formic acid 60:35:5:1 for step 2. Quantitative determination by absorbance measurement at 440 nm. Deteciton of anthranoids in daylight and after derivatization with 10 % potassium hydroxide in methanol.

Chromatographia 65 (3-4), 239-243 (2007). TLC of solasodine in various Solanum species on silica gel with a developing solvent containing an organic acid to form ion pair complexes of solasodine with the acid dye. The resulting colored complex was quantified by absorbance measurement at 461 nm. Linearity was between 79 and 495 ng/spot with a correlation coefficient of 0.995. The method eliminates post derivatization steps and the problem of background interference. Application of the method to determine solasodine content in various herb samples, herb extract and their formulations showed an accuracy of 98.5 ± 2.8 % without matrix interference.

Anal. Chim. Acta 641 (1-2), 52-58 (2009). Comparison of classical filtering techniques (Savitzky–Golay, Adaptive Degree Polynomial Filter, Fourier denoising, Butterworth and Chebyshev IIR filters) and wavelet shrinkage (31 mother wavelets, 3 thresholding techniques and 11 decomposition levels) with the original noisy signal and a reference signal which was denoised experimentally by averaging 64 measurements. The best similarity to the reference signal was obtained with filters, however the signal was slightly oversmoothed. The wavelet shrinkage method gave less denoised signals. There was a significant influence of the thresholding technique and decomposition level, and best conditions were at level 2 or 3 and soft thresholding), whereas changing of the mother wavelet almost did not change the result. The presented results can be used as general recommendations for denoising densitometric fingerprints before applying further chemometric algorithms. The best choices were: Savitzky–Golay filter of appropriate window width (optimized against autocorrelation) or wavelet shrinkage with Haar wavelet, soft thresholding and high decomposition level.