J. Planar Chromatogr. 33, 631-646 (2020). HPTLC of azilsartan medoxomil (1) and chlorthalidone (2) on silica gel with toluene - methanol - ethyl acetate - formic acid 35:10:5:1. Quantitative determination by absorbance measurement at 241 nm. The hRF values for (1) and (2) were 55 and 36. Linearity was between 800 and 4000 ng/zone for (1) and 250 and 1250 ng/zone for (2), respectively. Intermediate precision was below 2 % (n=3). The LOD and LOQ were 15 and 44 ng/zone for (1) and 10 and 32 ng/zone for (2). Recovery was between 100.8 and 101.7 % for (1) and 99.4 and 101.0 % for (2).

J. Planar Chromatogr. 33, 231-244 (2020). HPTLC of apremilast on silica gel with toluene - methanol - ethyl acetate 7:2:1. Quantitative determination by absorbance measurement at 241 nm. The hRF value for apremilast was 63. Linearity was between 200 and 1000 ng/zone. Inter-day and intra-day precision were below 1 % (n=3). The LOD and LOQ were 4 and 13 ng, respectively. Recovery rate was between 99.7 and 100.0 %. Apremilast was subjected to acidic, alkaline, oxidative, dry heat, neutral, and photolytic degradation conditions. The method was implemented using a quality risk management and quality by design approach for regulatory requirements.

Indian J. Pharm. Sci. 72(2), 249-252 (2010). HPTLC of rosiglitazone on silica gel with methanol - toluene - chloroform - triethyl amine 2:161:1. Caffeine was used as internal standard. The hRf value of rosiglitazone was 31 and of caffeine 52. Densitometric evaluation at 264 nm. The method was linear in the range of 5-50 µg/band with average recovery of 99.8-100.2 %. The method was suitable for content uniformity testing according to USP and could be used for stability studies as well.

62nd Indian Pharmaceutical Congress Abstract No. F-258 (2010). TLC of nebivolol HCl and hydrochlorothiazide on silica gel with methanol – chloroform – toluene – triethylamine 10:25:14:1. Quantitative determination by absorbance measurement at 284 nm. The hRf value of nebivolol was 78 and of hydrochlorthiazide 41. The method was linear in the range of 5-100 ng/band and 20-140 ng/band for nebivolol HCl and hydrochlorothiazide, respectively. Recovery was in the range of 98.8-100.0 % for both drugs.

J. Ethnopharmacol. 175, 131-137 (2015). HPTLC of 11-hydroxymustakone (1), N-formylannonain (2) and yangambin (3) in Tinospora cordifolia on silica gel with chloroform - ethyl acetate - methanol 130:80:3. Detection by dipping into anisaldehyde sulfuric acid reagent, followed by heating at 100 °C for 5 min. Quantitative determination by absorbance measurement at 366 nm. LOD and LOQ were 75 and 225 ng/zone for (1), 150 and 450 ng/zone for (2) and 30 and 90 ng/zone for (3), respectively. The intermediate precision was below 3 % (n=3). Recovery for (1) to (3) was in the range of 99-108 %.

J. Chromatogr. 396, 437-440 (1987). Reversed-phase TLC on RP-18 silica with 1. methanol, 2. ethanol, 3. acetonitrile, 4. acetone, 5. ethyl acetate, and 6. chloroform. Detection under UV 254 nm. (More than 40 solvent systems were tested.)

Proc. 6th Int. Symp. Instrum. Planar Chromatogr., (Interlaken 1991), Inst. Chromatogr., Bad Dürkheim, FRG, 185-193 (1991).Various benzodiazepines, some designer drugs e.g. MDA, MDMA, MDE, and sodium edetate (EDTA), were detected by FTIR scanning of the separated peaks on TLC plates. Automated multiple development (AMD) has been used for the separation of closely related substances. Using caffeine as an example, 3 different evaluation procedures were described.

J. Chromatogr. 669, 275-276 (1994). Discussion of the extension of the title compound to five-membered heteroaromatic rings containing 1-4 nitrogen atoms, as a selective chromogenic reagent. 22 compounds were examined. Discussion also of the reaction mechanisms.