Food Control. 122, 107816 (2021). HPTLC of histamine in fish samples on a silica gel read-out strip coated with a ninhydrin@TiO2 complex (0.1 M titanium butoxide and 5 % ninhydrin as precursors) as self-visualization nanomaterial in the histamine target zone (hRF value of 24). Samples were developed using n-butanol - acetone - ammonia 20:5:2. Detection after heating at 80 °C for 30 s. Linearity was between 15 and 320 mg/kg. The LOD for histamine was 5 mg/kg. 

Chem. Asian J. 15(19), 3044-3049 (2020). The studied rotaxane combines a dibenzocrown of 8 ethers (DB24C8) with an axle chain (Ax) containing two amines, one of them in an aniline group, allowing stability of the rotaxane even when the other one is unprotonated. TLC on silica gel in 4 steps, with detection under UV light or after derivatization with phosphomolybdic acid in ethanol. (1) Before the synthesis of the rotaxane, unprotonated Ax was isolated by preparative TLC of the protonated Ax obtained by addition of HCl or toluenesulfonic acid (TsOH); the mobile phases were chloroform – methanol 10:1 and toluene – tetrahydrofurane 3:2, respectively. The isolated molecules were confirmed as totally unprotonated Ax by NMR, suggesting a complete loss of HCl and TsOH on the silica gel layer. (2) After synthesis, unprotonated rotaxane, pure vs. monoprotonated by the addition of 10 different acids (and purified by column chromatography CC), was applied on TLC plates and developed with dichloromethane – acetone – water 3:16:1; the hRF values were very different, depending on the counter-anions from the used acids. (3) The same behavior (except with sulfuric acid) was observed under the same conditions when CC was omitted (unprotonated rotaxane samples were mixed with each of the acids, or with two acids at the same time for acid-competitive TLC analysis). (4) When unprotonated rotaxane was applied under the same conditions as in step (3) with the sodium salts instead of the acids, the behavior was similar (except for the shapes of the spots, due to the salts in excess). The rotaxane can thus be used for the TLC separation and detection of sodium salts, by forming salts of protonated rotaxane with the anion afforded by these sodium salts. The rotaxane protonation seems to be promoted by the methanol of the spotting mixture; indeed, when step (3) was performed with the mobile phase chloroform – methanol 10:1, a second zone appeared because methanol formed a salt with the rotaxane (identified by NMR).

J. Planar Chromatogr. 33, 669-677 (2020). HPTLC of tris(2-chloroethyl)amine (HN-3) on silica gel with benzene - methanol - triethylamine 425:75:1. Detection by spraying with derivatization reagent (2mg/mL of KMnO4 with 4 mL of H3PO4). The method allowed to study the influence of pH on the degradation of HN-3 and the triethanolamine rate of appearance.

Food Control. 22, 1154-1157 (2011). TLC of histamine in fish and fishery products on cellulose with ammonia - ethanol 1:3. Detection by spraying with Pauly's reagent (equal mixture of 20 mM sulfanilic acid in a 1 M HCl solution and 200 mM sodium nitrite solution, followed by adding 10 % anhydrous sodium carbonate in a 5 % ethanol solution). Color intensity was recorded using a digital camera, followed by imaging processing. Linearity was between 30 and 1000 ng/zone for histamine. Intermediate precision was below 5 % (n=3). The LOD was 20 ppm (2 mg/100 g). Recovery rate was between 93 and 98 %.

Food Control. 103, 111-118 (2019). Thin layer chromatography in tandem with surface-enhanced Raman scattering (TLC-SERS) of histamine in tuna samples on diatomaceous earth plates with ethanol - ammonia 3:1. Detection by spraying with Pauly's reagent (equal mixture of 20 mM sulfanilic acid in a 1 M HCl solution and 200 mM sodium nitrite solution, followed by adding 10 % anhydrous sodium carbonate in a 5 % ethanol solution). Gold nanoparticles were deposited on the plate zone and measurements were performed using a Raman spectrometer with an excitation laser wavelength of 785 nm.

J. Planar Chromatogr. 20, 231-233 (2007). TLC of cadaverine and ornithine on calcium sulfate (and silica gel) with methanol. Detection by spraying with 0.2 % ethanolic solution of ninhydrin and then heating the plates at 110 °C for 15 min. Quantitation by scraping the spot from the plate and measuring the absorbance at 550 nm. The lower limit of detection was found to be 0.75 µg/zone of ornithine.

Journal of Pharmacy Research 3(8), 1997-1999 (2010). TLC on silica gel (plates pre-washed with methanol) with methanol - water - acetic acid 80:20:1. The hRf value of ranitidine HCl was 27 and of dicyclomine HCl was 67. Derivatization by exposure to iodine vapor. Densitometric evaluation at 410 nm. The method was linear in the range of 400-2400 ng/band for dicyclomine hydrochloride and 150-900 ng/band for ranitidine hydrochloride. The mean recovery was 98.8 ± 0.5 % for ranitidine HCl and 99.1 ± 0.8 % for dicyclomine HCl.

J. Planar Chromatogr. 26, 354-357 (2013). HPTLC of free duloxetine in human serum on silica gel with acetone - benzene - triethylamine 10:9:1. Quantitative determination by absorbance measurement at 235 nm. The hRf of duloxetine was 32. Linearity was between 35 and 140 ng/zone. LOD and LOQ were 10 and 35 ng/zone. Recovery (by standard addition) was found to be 92.9-97.6 %. Intra- and inter-day precision values were below 1.8 % and 5.7 %, respectively.