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.

Molecules, 26 (24), 7683 (2021). Samples were ultrasound-assisted extracts of fruit puree and juice (pre-treated with sulfur dioxide or ascorbic acid) of Ananas comosus (Bromeliaceae) and Mangifera indica (Anacardiaceae). HPTLC on silica gel with toluene – ethyl acetate – methanol – formic acid 120:90:35:3. Detection under white light, UV 254 nm and 366 nm, before and after  derivatization by immersion (2 s, 3 cm/s) into anisaldehyde sulfuric acid reagent and  diphenylamine aniline reagent, followed by heating at 110 °C for 5 min. Effect-directed analysis using automated immersion: A) for free radical (DPPH•) scavengers; B) for enzymatic inhibition (acetyl-cholinesterase, tyrosinase); C) for activity against Gram-negative (Aliivibrio fischeri bioluminescence assay) or Gram-positive bacteria (Bacillus subtilis bioassay). Active compounds were far more present in puree than in juice extracts, and differences were also seen between cultivars. Ascorbic acid (hRF 37), used as additive for the mango puree, was active as antioxidant and as transiently disruptive for A. fischeri metabolism and bioluminescence.

J. Chromatogr. A 1218 (19), 2793-2811 (2011). A review on the forensic examination of writing ink on documents. The focus in ink analysis is on screening questioned samples and on verifying their compounds in relation to control ink samples. Description of a project designed to develop improved standardization procedures to ensure the best possible reproducibility between analyses run on different HPTLC plates. HPTLC of ink samples (punched from written documents and extracted with tetrahydrofuran – water 4:1) on silica gel with n-butanol – ethanol – water 10:2:3 without chamber saturation. Detection by densitometric measurement of absorption intensities of each point of the elution track directly at 31 wavelengths between 200 and 700 nm.

J. Planar Chromatogr. 9, 146-148 (1996). HPTLC of methyl-, ethyl-, propyl-, and butylparaben on RP-18 with acetone - water without prior chamber saturation; detection under UV 254 nm. Quantification by densitometry at 254 nm (absorbance).

J. Chromatogr. Sci. 46 (4), 298-303 (2008). HPTLC of three surfactants, cetyltrimethylammonium bromide (CTAB), dodecyltrimethylammonium bromide (DTAB), and polyoxyethylene (20) sorbitan monolaurate (Tween 20), on silica gel with 5 % aqueous thiourea - acetone - methanol 3:1:1. Evaluation of the effect of the carbon chain length of alcohols (methanol, ethanol, n-propanol, and n-butanol) on the mobility of these surfactants. The comparative study was performed with sulfur- (thiourea) and oxygen- (urea) containing compounds in the eluent. Investigation of the interference on the resolution of the mixture of CTAB, DTAB, and Tween 20, due to presence of metal cations as impurities.

Analyst 112, 433-436 (1987). Description of a technique for the identification of compounds separated by HPTLC using fast atom bombardment mass spectrometry (FAB-MS) without any extraction procedure between the two analysis steps. Discussion of the advantages of smaller samples, shorter analysis time and less opportunities for contamination to occur than with conventional extraction methods. Identification of surfactants in mixed systems. Detection of amine antioxidants in gas oils at levels below 20 ng/µL.

J. Planar Chromatogr. 5, 103-117 (1992). TLC of over one hundred and fifty surfactants in six TLC systems; compilation of a retention data base to facilitate identification of surfactants in commercial cleaners. Scanning densitometry was used to record the reflectance spectra of the UV-absorbing compounds. Rapid and inexpensive TLC method for differentiation and characterization of surfactants.

J. Planar Chromatogr. 20, 303-306 (2007). TLC of p-hydroxybenzoic acid, methyl p-hydroxybenzoate, ethyl p-hydroxybenzoate, propyl p-hydroxybenzoate, benzoic acid, sodium benzoate, sorbic acid, potassium sorbate, salicylic acid, butylated hydroxyanisol, and butylated hydroxytoluene on stannic silicate with n-hexane - ethyl methyl ketone - acetic acid 80:20:3. Quantitation by scanning densitometry at 270 nm. The limit of detection and quantitation for p-hydroxybenzoic acid was 0.05 and 0.51 µg/zone, respectively.