J Chromatogr A, 1602, 458–466 (2019). HPTLC of caffeine, physostigmine (alkaloids) and hydroethanolic extract of Peganum harmala seeds (Nitrariaceae, Zygophyllaceae) on silica gel prewashed twice with methanol – water 3:1, followed by 1 h drying at 120 °C. Separation, after 5 min chamber saturation, with ethyl acetate – methanol – ammonia (25%) 85:11:4 (basic mobile phase) or ethyl acetate – toluene – formic acid – water 16:4:3:2 (acidic mobile phase, requiring neutralization with phosphate-citrate buffer). Derivatization with Dragendorff’s reagent and with anisaldehyde sulfuric acid. Effect-directed analysis by spraying A) with Gram-negative bioluminescent Aliivibrio fischeri suspension for antibacterial activity (caffeine was used as standard); B) with acetyl- and butyryl-cholinesterase (AChE / BChE) solutions for enzymatic inhibition. For AChE and BChE asssays, classical immersion into the enzyme solutions was also used for comparison, and inhibition densitometry for active analytes was performed by inverse scan measurement (fluorescence without optical filter) at 546 nm using a mercury lamp; activity was expressed as physostigmine equivalents. Active bands were eluted (only after basic MP) with methanol through the oval elution head of a TLC-MS interface pump, into a quadrupole-Orbitrap mass spectrometer. Full scan mass spectra (m/z 50−750) in positive ionization mode were recorded using heated electrospray ionization (HESI, spray voltage 3.5kV, capillary temperature 270°C). By comparison to literature, AChE inhibitors (also active against A. fischeri) were assigned to be harmine, harmaline and ruine (β-carboline alkaloids), and BChE inhibitors were harmol (same class) and vasicine and deoxyvasicine (quinazoline alkaloids, also called peganine and deoxypeganine). Piezoelectric spraying had the following advantages over automated immersion: (1) it covered the whole plate surface; (2) required much lower volumes of solutions; (3) applied always fresh enzyme or reagent solutions, thus avoiding gradual inactivation; (4) avoided zone distortions, shifts or tailings occurring during immersion or withdrawal of the plate, or due to the hydrophilicity of compounds.

J. Planar Chromatogr. 32, 55-57 (2019). TLC of dimethyl phthalate, diethyl phthalate, di-n-butyl phthalate, diisobutyl phthalate, diallyl phthalate, and bis(2-ethylhexyl) phthalate on silica gel with petroleum ether - ethyl acetate - phosphoric acid 9:1:1. Detection by spraying with 0.1 % 2,6-dichlorophenolindophenol with the instantaneous appearance of pink-colored zones.

J. of Chromatogr. A 1218 (19), 2676-2683 (2011). A review on bioautography on TLC plates as an important means of detecting the biological activity of a sample. The technique requires only small amounts of sample, is ideal for the investigation of plant constituents which often occur as complex mixtures, and can be used for the target-directed isolation of these constituents. In contrast to HPLC, many samples can be run at the same time on TLC, and organic solvents, which cause inactivation of enzymes or death of living organisms, can be completely removed before biological detection. Many bioassays are compatible with TLC and antimicrobial, radical scavenging, antioxidant activities and enzyme inhibition tests can be applied.

The usage of double bonds photoisomerization for identification of organic compounds by thin-layer chromatography. J. Liquid Chromatogr. 8, 1239-1246 (1985). Presentation of a TLC technique combining chromatographic separation and identification of organic compounds containing double-bonds. Method based on different chromatographic mobility of Z- and E- isomers, and applied for the identification of aromatic azo- and azoxycompounds, stilbene derivatives and unsaturated acids.

Anal. Chim. Acta 192, 309-313 (1987). Description of 3 fluorescent derivatization reagents for compounds having hydroxyl and/or amino groups, which were stable at room temperature and condense stechiometrically with alcohols, amines and amino acids in the presence of alkali to give strongly fluorescent derivatives. Pre-chromatographic derivatization followed by TLC and HPLC.

J. Chromatogr. 504, 456-463 (1990). TLC of title compounds on cellulose or silica with one of the following solvents; 1) 2-methylpropan-2-ol - butanone - propanone - methanol - water - NH3 40:20:20:1:14:5, 2) butanol - propanone - acetic acid - water 35:35:10:20. Detection: spraying with 2,4-dinitrophenylpyridium chloride in methanol 200 mg/L for cellulose and 100 mg/L for silica - placing the plate in sealed glass tank with alkaline atmosphere for 15 min, keeping plate in the dark for 24 h before recording the fluorescence.

Analyst 119, 415-516 (1994). Presentation of a spray reagent for the detection of carbamate insecticide carbaryl, consisting of 1% ammonium cerium (IV) nitrate in 20%(v/v) hydrochloric acid, which reacts exclusively with the hydrolysis product of carbaryl, 1-naphthol, and forms a violet complex. Sensitivity, about 100 ng.

J. Chromatogr. A 750, 403-407 (1996). TLC of organophosphorus insecticides, carbamates and pentachlorophenol, etc. on silica with tetrahydrofuran - hexane 7:25, and hexane - ethyl acetate 3:2. Detection by using biological or biochemical tests. Investigation of the relationship between the signal of the inhibition of cholinesterase and the concentration of the inhibitor using a constant enzyme concentration and a constant incubation time. Quantification by densitometry or videodensitometry.