J. Planar Chromatogr. 27, 58-65 (2014). HPTLC of ternary mixtures of cetirizine dihydrochloride (1), pseudoephedrine (2), and/or phenylpropanolamine (3) and paracetamol (4) on silica gel with methanol - water 199:1. Quantitative determination by absorbance measurement at 257 nm. The hRF values for compounds (1) to (4) were 66, 16, 23 and 83, respectively. Linearity was in the range of 1-4 µg/zone for (1), 3-10 µg/zone for (2), 4-8 µg/zone for (3) and 5-100 µg/zone for (4), respectively. The intermediate/interday/intra-day precisions were below 2 % (n=5). The LOD and LOQ were 0.3 and 1 µg/zone for (1), 0.9 and 3 µg/zone for (2), 1.2 and 4 µg/zone for (3) and 1.5 and 5 µg/zone for (4), respectively. Mean recoveries for (1) to (4) were close to 100 %.

J. AOAC Int. 98, 1226-1233 (2015). HPTLC of three phosphodiesterase type 5 inhibitors, sildenafil (1), vardenafil (2), and tadalafil (3), and eight of their analogs, hydroxyacetildenafil (4), homosildenafil (5), thiohomosildenafil (6), acetildenafil (7), acetaminotadalafil (8), propoxyphenyl (9), hydroxyhomosildenafil (10), hydroxyhomosildenafil (11) and hydroxythiohomosildenafil (12) in finished products on silica gel with TBME - methanol - ammonia 28% 20:2:1. Detection under 254 and 366 nm UV light and by absorbance measurement at 232 nm. LOD was 30 ng/zone for all substances. Confirmation by HPTLC-ESI-MS. The method was successfully_x000D_ applied to screening of 45 commercial lifestyle products. Of those, 31 products tested positive for at least one illegal component (sildenafil, tadalafil, propoxyphenyl, hydroxyhomosildenafil, or dimethylsildenafil).

J. Planar Chromatogr. 29, 453-461 (2016). HPTLC of chlorzoxazone (1) and diclofenac potassium (2) in the presence of the nephrotoxic chlorzoxazone degradation product_x000D_
2-amino-4-chlorophenol (3) on silica gel with chloroform ‒ ethanol ‒ triethylamine 90:10:1. Quantitative determination by absorbance measurement at 230 nm. The hRF values for (1) to (3) were 63, 35 and 42, respectively. Linearities ranged between 1.5-5 μg/zone for (1), 0.5-4 μg/zone for (2) and 0.4-4 μg/zone for (3). The intermediate precisions were below 1.3 % (n=3). The LODs and LOQs were 320 and 980 ng/zone for (1), 140 and 450 ng/zone for (2) and 120 and 370 ng/zone for (3), respectively. Average recoveries were 100.2 % for (1), 99.3 % for (2) and 99.4 % for (3).

J. Planar Chromatogr. 30, 363-374 (2017). HPTLC of acetylsalicylic acid (1) and its related compound salicylic acid (2) on silica gel with n-hexane – diethyl ether – 80 % acetic acid 7:2:1. Good quality densitograms with well separated and symmetric peaks of (1) and (2) were achieved. Detection with the following reagents: Janus blue, bromophenol blue, bromocresol blue, hydrogen peroxide (without heating and with heating to 90 °C during 60 min), 1 % sodium hydroxide (with heating to 45 °C and also with heating to 90 °C during 60 min), brilliant green, malachite green, and thymol blue.

J. Planar Chromatogr. 31, 489-495 (2018). HPTLC of abacavir sulfate (1), lamivudine hydrochloride (2), and dolutegravir sodium (3) on silica gel with ethyl acetate ‒ ethanol ‒ acetone ‒ ammonia 2239:370:250:75. A factorial design was utilized to aid in method development and optimization. Quantitative determination by absorbance measurement at 267 nm. The hRF values for (1) to (3) were 65, 34 and 26, respectively. Linearity ranged between 4.8-14.4 μg/zone for (1), 2.4-7.2 μg/zone for (2) and 0.4-1.2 μg/zone for (3). LOD and LOQ were 997 ng/zone and 3022 ng/zone for (1), 254 ng/zone and 771 ng/zone for (2), and 100 ng/zone and 304 ng/zone for (3), respectively. The intermediate precision was <2 % (n=3). Recoveries were found in the range of 98.1–101.0 % for (1), 98.3–100.00 % for (2), and 98.5–101.3 % for (3), respectively._x000D_

(Allopurinol preparation for intravenous injection.) Acta Pharmac. Hungarica 54, 187-192 (1984). TLC of allopurinol on silica with chloroform - methanol 3:2 Detection by UV 254 nm.

(TLC in the laboratory of a chemist's shop.) Dtsch. Apoth. Ztg. 125, 1223-1232 (1985). Identification of vitamins (A,D,E), salicylic acid derivatives, passiflorae herba, foliae rubus, solidago virgaurea, veronica officinalis and flores primulae by TLC. Detailed description including color pictures to facilitate the interpretation of TLC results.

Apoth. Ztg. 125, 2062-2068 (1985). Dtabilität von Barbitursäurederivaten in wässrigen Lösunge. (Stability of barbiturates in aqueous solutions.) TLC on silica with isopropanol - chloroform -23 % NH3 45:45:10. Phenylacetylurea was found to be the main product of hydrolytic degradation of phenobarbital. Stability testing of solutions of aminobarbital, barbital and phenobarbital in dependence of the pH-value showed minor degradation rate between pH 8.0 and 9.5 than at higher pH-values.