Proc. 6th Int. Symp. Instrum. Planar Chromatogr., (Interlaken 1991), Inst. Chromatogr., Bad Dürkheim, FRG, 409-417 (1991). TLC of 2,4,6-trinitrotoluene and its metabolites on silica with benzene - ether - methanol 60:3:1. Quantification by densitometry by absorbance at 260 nm. The method is well suitable for screening large numbers of samples as well as for research of the toxicology of the compounds in human body.

J. Planar Chromatogr. 4, 379-384 (1991). Two-dimensional overpressured TLC of five organophosphorus warfare agents (tabun, sarin, soman, DFP, VX) in the presence of 22 pesticides on silica with diisopropyl ether - benzene - THF - hexane 10:7:5:11 in the first direction and THF - hexane 2:3 in the second direction. Visualization by spraying with various reagents. Quantification by densitometry at 585 nm (absorbance).

J. Agric. Food. Chem. 42, 1247-1250 (1994). TLC of sophorosides on silica with chloroform - methanol - water 65:15:2. Visualization by spaying with a solution of 1-naphthol.

J. Planar Chromatogr. 8, 157-159 (1995). TLC of title compounds on silica with concentration zone with ethyl acetate - methanol - acetic acid 8:1:1. Simultaneous detection of clenbuterol and salbutamol by placing the plate in a vessel containing a chlorination solution (CCl4 - KMnO4 3%- hydrochloric acid 12%. After drying, spraying with detection solution (o-tolidine in acetic acid + KI in water). Confirmation of clenbuterol by development with ethyl acetate - methanol - NH3 17:2:1, spraying with modified Ehrlich‘s reagent and heating at 80 °C for 5 min. Confirmation of salbutamol after development with ethyl acetate - methanol - NH3 7:12:1, drying, and spraying with a 2 % solution of 4-aminoantipyrine followed by an 8 % solution of potassium ferricyanide.

International Laboratory News, February, 8A-8B (1994). HPTLC of clenbuterol in various matrices on silica in horizontal developing chamber from both sides with ethyl acetate - methanol - acetic acid 8:1:1 with chamber saturation. Derivatization by spraying with Bratton-Marshall reagent (first 1% sodium nitrite in 1 N HCl, then 0.4% N-(1-naphthyl)-ethylenediamine dihydrochloride in methanol). Quantification by densitometry (absorbance) at 525 nm. Detection limit 2.5 ng; determination limit 10 ng. Further betablockers can be detected with this method, like atenolol at hRf 8, salbutamol at 14, propranolol at 25, clenbuterol at 40 and labetalol at 44. Sample preparation includes deproteinization, defattening and final extraction from an alkaline aqueous phase. Very fast method - chromatography of 18 resp. 36 samples within 10 min.

J. Planar Chromatogr. 17, 355-359 (2004). HPTLC of aristolochic acid A, B, and C and numerous plant extracts on silica gel in a saturated twin-trough chamber using the upper phase of the mixture toluene - ethyl acetate - water - formic acid 20:10:1:1. Quantitative determination by fluorescence measurement at 366 nm after derivatization with tin(II) chloride reagent. The working range and linearity, LOD and LOQ (based on the calibration plot), and precision (n = 6), were validated with methods described by K. Ferenczi-Fodor et al., J. AOAC Int. 84 (2001) 1265-1276. The stability of the analyte during chromatography was established by two dimensional chromatography. The new method enables visual detection of the acids with certainty at very low levels (400 pg absolute of aristolochic acid A) in plant material and can therefore be used for screening Chinese drugs to ensure their safety on the basis of absence of aristolochic acid.

Food Res. Int. 40, 167-175 (2007). HPTLC of absinthin in absinthe beverage (from the wormwood plant Artemisia absinthium L.) on silica gel with acetone - acetic acid (98 %) – toluene – dichloromethane 1:1:3:5. Detection by dipping into a solution of acetic anhydride – sulphuric acid – ethanol 1:1:10, followed by heating for 5 min at 104 °C. Quantitative determination by absorbance measurement at 554 nm. The hRf value of absinthin was 64 and selectivity regarding matrix was given. Linearity was between 0.1 and 10 g/L. The precision was better than 13.5 % (intraday) and 15.8 % (interday). The limit of detection and quantification for absinthin was 0.05 and 0.11 g/L, respectively.

J. Planar Chromatogr. 21, 249-250 (2008). HPTLC of diazepam, oxazepam, nitrazepam, lorazepam, chlordiazepoxide, and flurazepam on silica gel in a saturated twin trough chamber with chloroform - methanol 9:1. Detection by spraying with 5 % sodium hydroxide solution followed by 1 % m-dinitrobenzene in dimethyl sulfoxide. Violet bands were obtained for diazepam, the other compounds did not react. The sensitivity of this reagent for diazepam is approx. 5 µg/spot.