J Chromatogr A, 1624, 461239 (2020). Samples were chemical standards of acetylcholinesterase (AChE) inhibitors (azamethiphos, caffeine, donepezil, galanthamine, methiocarb-sulfoxide, paraoxon-ethyl) and of neurotoxic compounds, as well as drinking or contaminated water samples enriched through solid phase extraction. HPTLC on spherical silica gel (pre-washed twice by 20 min immersion in isopropanol, heated 20 min at 120 °C before and after pre-washing with acetonitrile). First separation (preparative TLC) with automated multiple development (16 steps). Effect-directed analysis for AChE inhibitors by immersion (speed 5 cm/s, time 1 s) into enzyme solution, incubation 5 min at 37 °C and immersion into substrate solution (indoxyl acetate 2 % in methanol); visualization under UV 366 nm. Active zones from untreated layers were eluted through the oval head of a TLC-MS interface to a second plate for a second separation with a panel of other mobile phases. Bands of interest were eluted from the second layer with water through the oval elution head of the TLC-MS interface pump, into a RP18 liquid chromatography guard column, followed by a quadrupole time-of-flight mass spectrometer. Full scan mass spectra (m/z 100–1200) were recorded in negative and positive modes using electrospray ionization (and collision-induced dissociation for MS2). Among the water contaminants, lumichrome (riboflavin photolysis product), paraxanthine and linear alkylbenzene sulfonates were identified as AChE inhibitors.

A simple chromatographic system for the identification of inks. J. Chromatogr. 475, 451-456 (1989). Proposal of a simple TLC system for the identification of inks based on cellulose layer, solution of ammonium sulfate or 1% sodium chloride as developing solvent; UV detection and photo dokumentation.

Chinese Anal. Chem. (Fenxi Huaxue) 29 (9), 1109-1110 (2001). TLC on silica gel with 1) isopropanol - ethanol - NH3 2:2:1, 2) propanol - ethanol - NH3 2:2:1, 3) isopropanol - ethanol -water 1:1:1, and 4) propanol ethanol - water 1:1:1. Detection under UV 254 nm. Identification by finger print technique.

J. Chromatogr. 464, 213-219 (1989). Analytical OPLC of polypodoside A, B and C on silica with ethyl acetate - ethanol - water 130:27:20, chloroform - methanol - water 6:3:1 and the lower layer of hexane - chloroform - methanol - water 0.8:6:3:1. Detection by spraying with 60% sulfuric acid and heating at 110°C for 10 min.; densitometry. Also preparative OPLC.

Acta Chromatographica 14, 82-91 (2004). Comparative investigation of the group composition of ethanol extracts obtained from natural resins of different origin and geological age by TLC on silica gel with dichloromethane - methanol 10:1 for carboxylic acids and a-hydroxy and a-keto acids, and with hexane - benzene - methanol 2:6:1 for other compounds. Detection with phosphoric and sulfuric acid and under UV 254 nm for additional identification of unsaturated compounds. Discussion of the potential of using the characteristics of the chromatograms as an auxiliary tool for classification of natural resins and, especially important, fossil resins.

J. Liquid Chromatogr. 13, 1959-1965 (1990). TLC of natural waxes on silica with a solvent mixture. Detection by charring with sulfuric acid - water 1:1, and heating at 200 °C Investigation of the influence of heating time and amount of charring agent.

Relation between mobility and molecular size shown by size-exclusion chromatography. J. Chromatogr. A 1024 (1-2), 227-243 (2004). TLC of coal tar pitch and a petroleum vacuum residue with pyridine, acetonitrile, toluene and pentane. The bands of material detected were recovered in 1-methyl-2-pyrrolidinone (NMP) solvent and examined by size-exclusion chromatography (SEC) in NMP eluent. The relation between elution time in SEC and mobility on the TLC plate indicated that molecular size increased steadily with increasing immobility on the plate. This relation was reinforced by UV fluorescence spectroscopy in that the fluorescence moved to longer wavelengths with increasing immobility. The molecular size of the material excluded from the porosity of the SEC column remains undefined; some excluded material was found in all of the fractions from both samples. The valley of zero intensity separating the retained material from the excluded material may suggest a change of structure from near-planar in the retained region to three-dimensional in the excluded region.

J. Planar Chromatogr. 4, 293-298 (1991). HPTLC of bitumen (aliphatic compounds, aromatics, resins, and asphaltenes) on silica with heptane; further successive elution with dichloromethane and THF resp. Quantification of aromatics by densitometry (absorbance) at 254 nm; for asphaltenes and the saturates by immersion in a solution of berberine sulfate and densitometry (fluorescence) at 264 nm.