by thin-layer chromatography) (Chinese). J. Chinese Trad. Patent Med. (Zhongchengyao) 27 (8), 941-944 (2005). TLC of betaine on silica gel with acetone - ethanol - hydrochloric acid 10:6:1. Detection by spraying with a solution of potassium iodobismuthate. Quantitative determination by densitometry at 515 nm. Validation regarding linearity range (8.0 - 39.0 µg, r = 0.9992), precision (RSD = 1.62 %, n = 6), reproducibility (RSD = 2.14 %, n = 6), and recovery (99.75 %, RSD = 1.92 %, n = 6). Results are given for 12 real life samples. Discussion of the advantages of the method compared to HPLC.

Pharmazie 61, 15-17 (2006). TLC of seven local anesthetics (benzocaine, procaine, tetracaine, lidocaine, prilocaine, bupivacaine, articaine) and the related antiarrhythmic drug procainamide on silica gel with ethyl acetate - methanol - 32 % ammonia 96:2:3 with chamber saturation for 15 min. Detection a) under UV light at 254 nm; b) spraying with cobalt(II) thiocyanate solution; c) by subsequent spraying with Ehrlich’s reagent. Except for articaine/prilocaine all drugs could be distinguished. However, articaine could be distinguished from prilocaine and other local anesthetics by a colour reaction with copper(II) sulfate solution.

J. Planar Chromatogr. 28, 395-397 (2015). HPTLC of 25-B-NBOMe (a N-(2-methoxy)benzyl-substituted phenylethylamine hallucinogen) in seized blotters (small, square pieces of absorbant paper impregnated with LSD or other hallucinogens) on silica gel with cyclohexane – toluene – diethylamine 15:3:2. Quantitative determination by absorbance measurement at 298 nm. The hRF value for 25-B-NBOMe was 34. Linearity was in the range of 19-115 μg/zone. LOD and LOQ were 7 and 22 μg/zone. The intermediate precision was below 6.3 % (n=6). Average recovery was 98 %.

J. Chromatogr. 436, 73-79 (1988). Screening for tranquillizer residue in pig muscle, liver and kidney tissue by HPTLC on silica (two-dimensional) with 1. dichloromethane - acetone - 25% NH3 100:100:5 and 2. n-butanol - acetic acid - water 80:20:100 (organic layer). Detection under UV 254/366 nm. Detection levels were 25 µg/kg for propiopromazine, 50 µg/kg for azaperone and 125 µg/kg for carazolol.

J. Planar Chromatogr. 3, 236-242 (1990). HPTLC separation of anabolic steroids on silica; androgens and gestagens with cyclohexane - ethyl acetate - ethanol 24:16:1 in the first direction and chloroform - acetone 9:1 in the second direction; estrogens with chloroform - benzene - ethanol 36:4:1 in the first direction and hexane - ether - dichloromethane 4:3:2 in the second. An additional confirmation of the identity of the steroids is possible by HPTLC on silica RP-18 with methanol - water - toluene 13:4:1 in the first direction and hexane - dichloromethane - acetonitrile 8:2:1 in the second. Detection by fluorescence after immersion in a 5% sulfuric acid - ethanol solution for 30 sec and viewing under UV 366 nm. Method for routine HPTLC analysis.

J. Planar Chromatogr. 8, 78-80 (1995). HPTLC of nitroimidazoles (dimetridazole, metronidazole, ronidazole) in poultry on silica with ethyl acetate. Detection with fluorescamine (detection limit 15 - 20 ng) and by spraying with pyridine, waiting for 1 min and illumination under UV 366 nm (detection limit 3 - 25 ng).

J. Planar Chromatogr. 10, 434-440 (1997). Investigation of the retardation behavior of ten closely related cyanobacterial hepatotoxins by parts I and II of the PRISMA system, operating in the irregular part of the PRISMA model. The mobile phase combination and the area of the triangular plane to be studied were selected in preassays and the retardation behavior was studied at sixteen selectivity points. The retardation of all the toxins followed a second-order function with high correlation. The three-dimensional retention surfaces described the mobility and the structural variances of the toxins. Cyanobacterial hepatotoxins behaved predictably in the selected system in the irregular part of the PRISMA model. HPTLC of 10 microcystins on silica with varying ratios of solvents. Densitometry at 240 nm.

Proc. Intern. Symp. on Planar Separations, Planar Chromatography 2001, pp. 313-320. OPLC of natural phenolic compounds (coumarins, furanochromones, flavonoids, anthocyanins) with ethyl acetate - chloroform 3:2; 9:1 and ethyl acetate - MEK - formic acid - 2 M HCl 65:10:6:9. Detection under UV 365 nm for coumarins and furanochromones; spraying with 1% methanolic diphenylboric acid b-ethylamino ester followed by 5 p. 100 ethanolic polyethyleneglycol 400, then observation at 365 nm for flavonoids and by direct visual observation for anthocyanins. Alkaloids were separated by semipreparative OPLC on aluminium oxide with hexane - ethyl acetate 1:1, ethyl acetate and ethyl acetate saturated with 28% NH3. Detection under UV 365 nm, or after spraying with Dragendorff's or iodoplatinate reagent. Quantitation by densitometry at 540 nm. AMD for Opium alkaloids on silica gel with methanol 100, methanol/acetone 50/50 v/v, dichloromethane 100, ethyl acetate, ethyl acetate/dichloromethane; visualization with potassium iodoplatinate.