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. Chromatogr. A 1164 (1-2), 298-305 (2007). TLC using staining reagents is fast, versatile and sometimes the only viable method method for analyzing organic compounds without chromophores. Investigation of quantitative TLC using staining reagents in combination with modern image analysis software showed that it is possible to get reliable measurements, suitable for high-throughput screening or physical organic investigations. Illustration of the range of detection and the errors for the different parts of the process, which are largely due to the staining process but can be diminished by measuring ratios of compounds.

J. Planar Chromatogr. 26, 26-30 (2013). Four new spray reagents for the detection of amino acids were introduced: (1) 0.25 % solution of benzoic acid in ethanol, (2) 0.1 % solution of p-fluorobenzoic acid in ethanol, (3) 0.1% solution of p-chlorobenzoic acid in ethanol and (4) 0.05 % solution of p-iodobenzoic acid in ethanol. Depending on the different amino acids tested the LOD on silica gel was in the range of 0.1-1.0 µg for all four reagents. For example for cysteine the LOD was 0.1 µg with reagents (1), (3), and (4), and 0.2 µg with reagent (2).

Chromatographia 20, 683-684 (1985). TLC of some purines on silica with iso-butanol MEK - NH3 - water 8:5:4:3 and propanol - NH3 water 16:3:1. Visualization by spraying with 1 % aqueous uranyl acetate and irradiating with UV at 254 or 366 nm. Detection limit 0.01/mg.

J. High Resol. Chrom. 12, 345-347 (1989). TLC separation of thiol compounds (captopril, coenzyme A, cysteamine HCl, cysteine HCl, glutathione) after derivatization with ammonium 7-flurobenzo-2-oxa-1,3-diazole-4-sulfonate (SBD-F) on HPTLC silica with isopropylether - methanol - water - acetic acid 9:8:2:1 as eluent in a twin trough chamber. Visualization under UV 366 nm, quantification by densitometry. Enhancement at signals by nitrogen- or helium-flushing.

J. Chromatogr. 541, 480-482 (1991). Description of a new, selective method for the detection of o-phenylenediamine and some of its derivatives on TLC plates by treating the chromatograms with Me trichloromethylacetimidate and exposing to pyridine vapor. Detection limits, between 80 and 2000 ng.

J. Chromatogr. A 724, 411-415 (1996). TLC of p-iodophenol and p-coumaric acid on cellulose with 0.1 M tris-HCl buffer (pH 8.5). Detection by spraying with a solution of 2mM luminol, 6 mM H2O2 and 0.744 U/mL peroxidase in a 0.094 M tris-HCl buffer (pH 8.5). Determination by densitometry with a single optical fibre that collected the emission signal to a spectrometer. Detection limit 38 ng and 14 ng respectively.