J. AOAC Int. 94, 1094-1099 (2011). TLC of caffeine and paracetamol in capsules and tablets on silica gel with n-hexane - ethyl acetate - ethanol 25:15:4. Detection at 254 nm. Quantitative determination by densitometry at 254 and 270 nm. The hRf value of caffeine and paracetamol was 48 and 73, respectively. Linearity was between 0.2-1.9 for caffeine and 0.03-1.5 µg/L for paracetamol. The detection limit of caffeine was 25 ng/L and of paracetamol 32 ng/L. The precision was 1.9 % (n=6). Recovery (by standard addition) was 98-99.5 % for both compounds.

J. Planar Chromatogr. 24, 348-351 (2011). Study of the lipophilicity and specific hydrophobic surface area of fourteen 1,3-benzoxazol-2(3H)-ones substituted in the benzene ring (fluoro-, chloro-, bromo-, dibromo-, amino-, and nitro-derivatives). TLC on RP-18 with methanol - water, methanol - aminoacetic acid buffer pH 2.7, and methanol - aminoacetic acid buffer pH 11.6. The concentration of methanol in the mobile phase ranged from 30-90 % in all cases. Detection under UV 254 nm. The linear correlation between the volume fraction of methanol and values over a limited range were established with good correlation coefficients (r > 0.98). The obtained results were compared with calculated partition coefficients.

J. Liq. Chromatogr. Relat. Technol. 35, 28-39 (2012). HPTLC of metformin hydrochloride and glipizide in tablet formulation on silica gel with water - methanol 3:1 + 1 drop ammonia. Quantitative determination by absorbance measurement at 236 nm. The hRf value of compounds (1) and (2) were 22 and 85 and selectivity regarding matrix was given. Linearity was in the range of 5000-25000 ng/band for (1) and 50-250 ng/band for (2). Limits of detection and quantification were 991 and 3003 ng/band for (1) and 10 and 29 ng/band for (2), respectively. Recovery (by standard addition) was between 98.1 and 101.5 % for both (1) and (2).

J. Planar Chromatogr. 25, 150-155 (2012). HPTLC of methocarbamol (1) and its related substance guaifenesin (2) in two ternary mixtures with ibuprofen (3) and diclofenac potassium (4) on silica gel with ethyl acetate - acetone - triethylamine 62:35:6 + 1 drop formic acid. Quantitative determination by absorbance measurement at 222 nm for the first mixture and 278 nm for the second mixture. The hRf values for agents (1) to (4) were 78, 54, 14 and 12, respectively. Linearity was in the range of 2-12 µg/band for (1), 2-10 µg/band for (2), 4-20 µg/band for (3) and 0.2-2.2 µg/band for (4). The intermediate/inter-day/intra-day precision was below 1.5 %. Mean recovery for (1) to (4) was between 100.7 and 100.8 %.

J. Planar Chromatogr. 25, 145-149 (2012). HPTLC of labetalol hydrochloride on silica gel with ethyl acetate - methanol 4:1 + 1 drop ammonia. Quantitative determination by absorbance measurement at 309 nm. The hRf of labetalol was 69. Linearity was in the range of 400-2400 ng/band. The intermediate/interday/intra-day precision was below 2 %. Recovery was in the range of 98.6-100.5 %.

J. Planar Chromatogr. 28, 83-89 (2015). HPTLC of irbesartan in tablets and plasma on silica gel with acetonitrile - chloroform - glacial acetic acid 30:19:1. Detection by exposure to concentrated hydrochloric acid vapor for 10 min. Quantitative determination by fluorescene measurement at 255/>400 nm. The hRF value of irbesartan was 40. Linearity was between 7 and 90 ng/zone. The intermediate intra-day and inter-day precisions were below 2.8 % (n=6). The LOD and LOQ were 2 and 6 ng/zone, respectively. Recoveries were in the range of 96.9-98.6 % in tablets and 95.8-97.4 % in plasma.

J. Liq. Chromatogr. Relat. Technol. 38, 1731-1739 (2015). HPTLC of asenapine maleate in pharmaceutical formulations on silica gel with methanol. Quantitative determination by absorbance measurement at 235 nm. The hRF value for asenapine was 43. Linearity was in the range of 300-1800 ng/zone. LOD and LOQ were 39 and 119 ng/zone, respectively. The intermediate precision was below 0.2 % (n=3). Recovery was in the range of 99-102 %. Results were comparable to those obtained by HPLC.

J. Planar Chromatogr. 29, 462-468 (2016). HPTLC of dantrolene sodium (1) and its process-related impurity 5-(4-nitrophenyl)-2-furaldehyde (2) on silica gel with chloroform – ethyl acetate – glacial acetic acid 1000:500:1. Quantitative determination by absorbance measurement at 380 nm. The hRF values for (1) and (2) were 22 and 83, respectively. Linearity ranged between 100-1500 ng/zone for (1) and 100-2000 ng/zone for (2). The intermediate precisions were below 0.3 % (n=3). The LODs and LOQs were 33 and 99 ng/zone for (1) and 32 and 96 ng/zone for (2), respectively. Average recoveries were 99.5 % for (1) and 100.2 % for (2).