J. Liq. Chromatogr. Relat. Technol. 41, 15-16 (2019). HPTLC of thymine (1), uracil (2), adenine (3), cytosine (4), guanine (5) and guanosine (6) in Ganoderma lucidum and Cordyceps sinensis on silica gel with dichloromethane - methanol - formic acid 160:45:16. Quantitative determination by absorbance measurement at 254 nm. Identification of nucleobases in the samples was reconfirmed by hyphenated HPTLC-MS. The hRF values for (1) to (6) were 83, 73, 46, 32, 23 and 10, respectively. The intermediate precision was below 5 % (n=3). 

J. Liq. Chromatogr. Relat. Technol. 42, 367-379 (2019). Review of the application of TLC and HPTLC for the analysis of counterfeit pharmaceutical products published from 2008 to 2019, including methods reported in the Global Pharma Health Fund (GPHF) Minilab Manual and the U.S. Food and Drug Administration (FDA) Compendium. Applications of TLC-Raman spectrometry and TLC-mass spectrometry for the analysis of herbal medicines were also described. A special section covering the use of model process for the transfer of minilab manual and FDA compendium TLC screening methods to quantitative HPTLC-densitometry methods was also included.

J. Planar Chromatogr. 32, 273-283 (2019). HPTLC of trimetazidine dihydrochloride (1) and its potential impurities, namely, piperazinecarboxaldehyde (2), trimethoxybenzyl alcohol (3), and trimethoxybenzaldehyde (4) on RP-18 with acetonitrile - methanol - 0.1 % aqueous ortho-phosphoric acid (pH 6.2) 9:9:2. Quantitative determination by absorbance measurement at 254 nm. The hRF values for (1) to (4) were 21, 35, 50 and 85, respectively. Linearity was between 0.05-10 µg/zone for (1), 0.05-1.1 µg/zone for (2), 0.05-1.2 µg/zone for (3) and 0.04-1.0 µg/zone for (4). The intermediate precision was below 2 % (n=9). The LOD and LOQ were 20 and 50 ng/zone for (1) to (3) and 15 and 40 ng/zone for (4), respectively. Recovery rate was 99.6 % for (1), 100.5 % for (2), 100.1 % for (3) and 99.4 % for (4).

J. Planar Chromatogr. 32, 317-321 (2019). HPTLC of 2-chloroaniline (1) at trace levels
in quetiapine fumarate (2) on silica gel with toluene and methanol 7:4. Quantitative determination by absorbance measurement at 235 nm. The hRF value of (1) was 85. Linearity was between 2.5-12.5 ng/zone for (1) and 400-2400 ng/zone for (2). The intermediate precision was below 2 % (n=3). The LOD and LOQ of (1) were 0.02 and 0.05 ng/zone for (1) [Editor´s note: This seems to be erroneous.] and 1.27 and 3.87 ng/zone for (2), respectively. Recovery rate ranged between 98 and 100 % for (1) and (2).

J. Planar Chromatogr. 32, 329-334 (2019). HPTLC of orlistat on silica gel with chloroform - methanol 49:1. Detection by spraying with anisaldehyde - sulfuric acid, followed by heating at 120 °C for 5 min. Quantitative determination by absorbance measurement at 600 nm. The hRF value of orlistat was 75. Linearity was between 600 and 4000 ng/zone. The intermediate precision was below 2 % (n=6). The LOD and LOQ for orlistat were 140 and 466 ng/zone, respectively. Recovery rate was between 97.7 and 104.5 %.

J. Planar Chromatogr. 32, 323-327 (2019). HPTLC of mirabegron (1) and solifenacin succinate (2) on silica gel with methanol - ethyl acetate - triethylamine 80:20:1. Quantitative determination by absorbance measurement at 222 nm. The hRF values for (1) and (2) were 76 and 56, respectively. Linearity was between 2.0-5.5 µg/zone for (1) and 0.4-1.1 µg/zone for (2). The intermediate precision was below 2 % (n=3). The LOD and LOQ were 34 and 103 ng/zone for (1) and 20 and 61 ng/zone for (2), respectively. Recovery rate was between 98.5 and 101.2 % for (1) and 99.2 and 100.8 % for (2).

J. Planar Chromatogr. 32, 265-271 (2019). HPTLC of 24 anions on tri-n-butyl amine (TBA) impregnated silica gel with 13 mobile phases (methanol, dimethylformamide, diisopropyl ether, tetrahydrofuran, 2-propanol, dimethylformamide - methanol 1:1, dimethylformamide - diisopropyl ether 1:1, dimethylformamide - tetrahydrofuran, 1:1, dimethylformamide - 2-propanol 1:1, 0.1 M oxalic acid, 0.1 M tartaric acid, 0.1 M citric acid and 0.1 M succinic acid). The retention behavior was analyzed in aqueous and non-aqueous mobile phases. The hRF values were also correlated with their lyotropic numbers. 20 % TBA-impregnated silica gel was found very effective for binary and ternary separations of anions.
 

J. Planar Chromatogr. 32, 295-307 (2019). HPTLC of empagliflozin (1) and metformin (2) with ammonium acetate - methanol - acetonitrile - ethyl acetate 6:2:9:3. Quantitative determination by absorbance measurement at 254 nm. The hRF values for (1) and (2) were 49 and 81, respectivley. Linearity was between 2 and 10 µg/zone for (1) and 1 and 5 µg/zone for (2). The intermediate precision was below 2 % (n=3). The LOD and LOQ were 3 and 11 ng/zone for (1) and 110 and 331 ng/zone for (2), respectively. Recovery rate was between 98.4 and 99.8 % for (1) and 99.0 and 99.6 % for (2).