Analysis of choline esterase inhibitors. CBS 83, 4-5 (1999) HPTLC-AMD of choline esterase inhibitors on silica gel with a 15-step gradient from methanol via dichloromethane to hexane. Detection by spraying with butyryl choline esterase solution followed by incubation at 37 °C for 30 min, and spraying with fast blue salt mixed with alpha-naphthyl acetate followed by incubation at 37 °C for 5 min. Quantitative determination by absorbance measurement at 254 nm.

by automated multiple development. J. Planar Chromatogr. 19, 115-117 (2006). HPTLC of eight ginsenosides on silica gel after cleaning with isopropanol for 1 h with methanol - chloroform. Two gradient programs and two different values of increment in the development distance were compared. Visualization by spraying with A) Godin’s reagent (5% solution of sulfuric acid in ethanol), and B) 1% solution of vanillin in ethanol, followed by heating at 105°C for 10 min. Evaluation by scanning at 540 nm.

J. Planar Chromatogr. 22, 187-189 (2009). HPTLC of tamoxifen citrate ((Z)-2-[4-(1,2-diphenylbut-1-enyl)phenoxy]ethyldimethylamine citrate) on silica gel (prewashed with methanol - chloroform 1:1) by automated multiple development (AMD 2) using single-step isocratic development with toluene - methanol - glacial acetic acid 57:38:5. Detection under UV 254 nm. Quantitative determination by absorbance measurement at 256 nm. The limit of detection and quantitation was 25 and 52 ng/band, respectively.

CBS 119 (2017 12-13. HPTLC of hop extracts on silica gel (MS-grade) by automated multiple development using a 9-step AMD 2 gradient based on ethyl acetate – methanol – n-heptane. Quantitative determination by fluorescence measurement at 360/>400 nm with the deuterium lamp. The hRF of α-acids was 36 and of β-acids 65 and the matrix was well separated. With this study the differences in the bitter acid content of regional and varietal hops was determined. In most cases, the bitter hops contained more bitter acids than aromatic hops.

J. Planar Chromatogr. 5, 16-27 (1992). TLC of estrogens (estrone, equilin, equilenin, 17 a & ß-dihydroequilin, 17 a & ß-dihydroequilenin, estriol) on silica, C-2, C-8, C-18, NH2- and diol-modified, with different eluents in one- and two-dimensional separations. The optimized mobile phase based on cyclohexane and ethyl acetate provided best separation of estrogens containing C-17 hydroxy group epimers, those with a C-17 keto group were only separated in mobile phases containing triethylamine (or on NH2-layers in the absence of triethylamine). 2,4-dinitrophenylhydrazones of C-17-keto group estrogens enable their selective detection at 366/>400 nm.

J. Planar Chromatogr. 7, 344-348 (1994), Use of AMD for the improvement of the identification and determination limit by FTIR of hexobarbital to between one half and one third of their original values; AMD can be recommended for such application. When thinner silica gel layers on a reflecting carrier are used, these values can be reduced once again (by half). In order to achieve optimum results, certain procedures must be followed: dot spotting and mobile reference measurement taken at the level of the substance to be analyzed. Detection limits for hexobarbital = 55 ng, phenobarbital = 55 ng, caffeine = 30 ng, salicylic acid = 220 ng and ascorbic acid = 240 ng. The reasons for and significance of these different limits of identification are discussed.

Merck KGaA (Ed.): Chromatographie - Chronologie einer Analysentechnik - Praxis, Status, Trends, GIT Verlag mbH, Darmstadt, 96-100, ISBN 3-928865-21-8 (1996). Correlation between instrumental thin-layer chromatography and GLP (Good Laboratory Practice). Each step in TLC, e.g. sample application, development, evaluation, pre- or post chromatographic derivatization, is fully automated. The advantages and possibilities of each automated step are discussed. Instrumental TLC shows good reproducibility and high flexibility. Documentation regarding GLP is demonstrated by reports. Automated validation of instruments is shown.

CBS 91, 5-7 (2003). HPTLC-AMD of benzodiazepines from serum on lichrospher silica gel with a 9-step gradient based on methanol and diisopropyl ether over 80 mm. Densitometric evaluation by absorbance measurement at 230 and 320 nm followed by spectra recording from 200 to 330 nm.