J. Planar Chromatogr. 24, 376-380 (2011). HPTLC of stem bark extracts from D. melanoxylon and lupeol and betulin on silica gel, prewashed with methanol, with ethyl acetate - hexane 9:41 with chamber saturation for 3 min at 29 +/- 4 °C and 65 +/- 5 % relative humidity. The hRf value was 46 and 25 for lupeol and betulin, respectively. Quantitative determination by densitometry in absorption mode at 560 nm for lupeol and 510 nm for betulin. Detection by derivatization with 5 % methanol-sulfuric acid reagent. The LOD and LOQ was 40 and 100 ng/zone for lupeol and 50 and 100 ng/zone for betulin, respectively. The instrument precision and repeatability (n = 6) were 0.8 and 1.3 % for lupeol and 1.1 and 1.2 % for betulin, respectively. The linearity range was 100-500 ng/zone for both lupeol and betulin. The intra-day and inter-day precision was 1.1-1.7 % and 1.3-2.0 % for lupeol and 0.8-1.9 % and 1.9-2.2 % for betulin.

Brazilian Journal of Pharmacognosy 21, 818-823 (2011). This review describes recent advances in HPTLC automatization as a useful tool for the analysis of complex mixtures of natural products. The author also compares HPTLC with TLC and HPLC. The review provides a general perspective for HPTLC fingerprint approach for the analytical determination of botanicals.

J. Planar Chromatogr. 24, 222-226 (2011). HPTLC of lamotrigine in human serum with chloramphenicol as internal standard on silica gel, prewashed with methanol, with ethyl acetate - methanol - 32 % aqueous ammonia 17:2:1 in a saturated twin-trough chamber. Quantitative determination by densitometry at 280 nm. The hRf of lamotrigine was 37. Linearity was between 0.6 and 300 ng/band, corresponding to 0.06-30.00 ng/µL lamotrigine in human serum after extraction and application of 1 µL to the chromatographic plate. The correlation coefficient was 0.998. Intra-assay and inter-assay precision (%RSD) were in the range of 0.5-2.9 % (n = 3) and 1.6 -2.9 % (n = 9), respectively. LOD and LOQ were 16 and 42 pg/zone, respectively. Recovery (by standard addition) was between 94.1-101.3 %, with %RSD not higher than 3.5 %.

J. Planar Chromatogr. 24, 48-52 (2011). HPTLC of hydroquinone on silica gel with chloroform - methanol 17:3 in a twin-trough chamber after saturation for 30 min at 25 °C. Quantitative determination by densitometry in absorbance mode at 289 nm. The hRf of hydroquinone was 51. Linearity was between 100 and 2500 ng/zone. Mean recovery was 99.2 %, with %RSD between 1.7-2.0 %. The intra-day precision (n = 3) as %RSD was 0.9-1.1 % and the inter-day precision 1.0-1.2 %. The LOD and LOQ was 39 and 116 ng/band, respectively.

J. Planar Chromatogr. 24, 72-76 (2011). HPTLC of sennoside A and B and gallic acid on silica gel with toluene - ethy acetate - formic acid - methanol 8:8:4:5. Quantitative analysis by densitometry at 270 nm. Linearity was between 114-427 ng/zone for sennosides A and B and 100-375 ng/zone for gallic acid. For sennosides A and B and gallic acid, hRf values were 26, 21 and 80, correlation coefficients were 0.95, 0.998, and 0.997, method precisions (%RSD, n = 6) were 1.1, 1.1 and 0.9 %, recoveries were 96.3-97.2 %, 98.1-100.8 % and 97.1-98.1 %, respectively. LOD andLOQ was 30 and 25 ng/zone for sennoside A, 20 and 99 ng/zone for sennoside B, and 66 and 82 ng/zone for gallic acid.

J. Liq. Chromatogr. Relat. Technol. 34, 1925-1937 (2011). HPTLC of p-hydroxy benzoic acid (1), chrysoplenol-D (2), p-methoxy benzoic acid (3) and casticin (4) in the aerial parts of Vitex trifolia on silica gel with chloroform - methanol 24:1 + 1 drop formic acid. Quantitative determination by absorbance measurement at 254 nm. The hRf values of compounds (1) - (4) were 25, 31, 63 and 87, respectively. LOD and LOQ were found to be 18-58 ng/zone for (1), 39-132 ng/zone for (2),15-52 ng/zone for (3) and 33-111 ng/zone for (4). Repeatability and reproducibility (%RSD) for (1)-(4) were found in the range of 0.8-1.2 % and 1.2-1.3 %, respectively. Recoveries were obtained in the range of 94.0-101.1 %, 97.8-102.0 %, 95.1-100.1 %, and 97.6-100.3 % for compounds (1) - (4), respectively.

J. Liq. Chromatogr. Relat. Technol. 35, 1289-1297 (2012). TLC of fourteen geometrically isomeric Co(III) complexes: three pairs of neutral fac-mer isomers, one pair of cis-trans isomeric complexes of neutral type and three pairs of cationic cis-trans isomers, on silica gel with mobile phases consisting of different ratios of water, methanol and sodium chloride. The retention behavior of the Co(III) complexes was investigated, revealing that the most selective systems were chromatographic systems with low content of water. A significant effect of sodium chloride on the retention was observed.

J. Planar Chromatogr. 25, 331-337 (2012). HPTLC of danazol on silica gel with hexane - acetone 3:2. Quantitative determination by absorbance measurement at 291 nm. The hRf value of danazol was 55. Linearity was in the range of 200-1200 ng/zone. Limits of detection and quantification were 1 and 4 ng/zone.