J. of Chromatogr. A 1241, 103-111 (2012). Development of a simple, fast, and efficient HPTLC method for the simultaneous quantitative determination of alcohols and acetates in Haitian vetiver essential oils (Chryzopogon zizanioides) and its acetylated form. TLC on silica gel with n-hexane – chloroform – ethyl acetate 16:12:1 at 47 % relative humidity. Detection with vanillin – sulfuric acid reagent. Quantification of the analytes by densitometry in absorbance mode at 530 nm. Preparation of the reference mixtures of alcohols and acetates by fractionation of Haitian vetiver oil or vetiver acetates, followed by purification of the fractions of interest by means of OPLC. Determination of the chemical composition of each reference fraction by using GC-MS and GC×GC-MS, and of their overall purity by HPTLC with good linearity (r2 = 0.9995 for alcohols, r2 = 0.9996 for acetates) in a concentration range of 40–200 ng/zone.

J. Liq. Chromatogr. Relat. Technol. 35, 1731-1749 (2012). HPTLC of atazanavir sulfate (1) and ritonavir (2) in fixed dosage on silica gel with toluene – methanol – glacial acetic acid – ethyl acetate 14:1:3:4. Quantitative determination by absorbance measurement at 254 nm. The hRf values of (1) and (2) were 50 and 63, respectively. Linearity was 30-300 ng/zone for (1) and 10-100 ng/zone for (2). The intermediate/inter-day/intra-day precision was 0.3 % for (1) and 0.7 % for (2) (n=6). The limit of detection and quantification was 16 and 49 ng/zone for (1) and 18 and 55 ng/zone for (2), respectively. Recovery (by standard addition) was 99.9 % for (1) and (2). The results were in accordance with those by a validated HPLC method.

Ethnomed. Ethnopharm. (1), 53-54 (2012). Cissus hexangularis Thorel ex Planch is a TCM herb. Its dried rattan is effective in relieving rheumatic pains and invigorating the circulation of blood, and is often used in drug preparations against rheumatism, pain or numbness, lumbar muscle degeneration and traumatic injury. TLC of the extracts and standards resveratrol and bergeninum on silica gel with chloroform – ethyl acetate – formic acid 30:20:1, detection by spraying with a solution of vanillin - ethanol - sulfuric acid 10:200:1.

J. Chil. Chem. Soc. 57, 1033-1035 (2012). HPTLC of propanolol hydrochloride (1) and flunarizine dihydrochloride (2) in combined dosage form on silica gel with methanol - toluene - ammonia 14:6:1. Quantitative determination by absorbance measurement at 267 nm. The hRf of compounds (1) and (2) were 63 and 48, respectively. Linearity was in the range of 800-4800 ng/zone for (1) and 200-1200 ng/zone for (2). Limits of detection and quantification were 25 and 75 ng/zone for (1) and 16 and 48 ng/zone for (2), respectively. Intermediate/intra-day/inter-day precision was below 2.0 % (n=6). Recovery for both (1) and (2) was between 99.3 and 100.9 %.

J. Liq. Chromatogr. Relat. Technol. 35, 1565-1584 (2012). HPTLC of negundoside (1), ursolic acid (2), eugenol (3), lupeol (4), and beta-sitosterol (5) in the leaves of Vitex Negundo on silica gel with toluene - methanol 9:1. Detection by dipping in anisaldehyde sulfuric acid reagent for approximately 1 min, followed by heating at 100 °C for 5 min. Quantitative determination by absorbance measurement at 525 nm. The hRf value of compounds (1) to (5) were 47, 61, 56, 54 and 38, and selectivity regarding matrix was given. Linearity was in the range of 200-800 ng/zone for (1), 72-576 ng/zone for (2), 200-1000 ng/zone for (3), 150-900 ng/zone for (4) and 80-480 ng/zone for (5). Limits of detection and quantification were 80 and 200 ng/zone for (1), 18 and 72 ng/zone for (2), 60 and 200 ng/zone for (3), 50 and 100 ng/zone for (4) and 20 and 60 ng/zone for (5), respectively. The method provides acceptable intra-day and inter-day precision for (1) to (5). The average recoveries for compounds (1) to (5) were found to be 99.9, 100.1, 99.7, 100.0, and 99.9 %, respectively.

J. AOAC Int. 96, 24-26 (2013). HPTLC of stevioside (1) and rebaudioside-A (2) in the leaves of Stevia rebaudiana on silica gel with ethyl acetate - ethanol - acetone - water 5:1:2:2. Detection by spraying with anisaldehyde - sulfuric acid reagent, followed by heating at 110 °C for 10-15 min. Quantitative determination by absorbance measurement at 580 nm. The hRf values of (1) and (2) were 34 and 28, respectively. Linearity was 1-7 µg/zone for both. LOD and LOQ were 127 and 387 ng/zone for (1) and 393 and 1191 ng/zone for (2). The interday and intra-day precisions were below 1.2 % (n=3). Recovery (by standard addition) ranged 89.6-93.9 % for (1) and 86.7-90.6 % for (2).

Food Chemistry. 139, 866-871 (2013). HPTLC of catechin (1), proanthocyanidin (PAC) A2 (2) and PAC-B1 (3) in American cranberry (Vaccinium macrocarpon) extracts on silica gel with dichloromethane - ethyl acetate - formic acid 6:10:1. Detection by dipping into a hydrochloric solution of 1 % (w/v) vanillin, followed by heating at 110 °C for 2 min. Quantitative determination by absorbance measurement at 254 and 366 nm. The hRf values of (1), (2) and (3) were 63, 48 and 25, respectively. Linearity was in the range of 0.6-5 µg/band. Intermediate precision was below 2.1 %. Average recoveries (by standard addition) were 98.4 % for (1), 99.6 % for (2) and 98.5 % for (3).

J. Planar Chromatogr. 26, 78-85 (2013). HPTLC of lamivudine (1), tenofovir disoproxil fumarate (2) and efavirenz (3) on silica gel with chloroform - methanol - toluene 30:4:1. Quantitative determination by absorbance measurement at 260 nm. The hRf values of (1), (2) and (3) were 20, 61 and 73, respectively. Linearity was in the range of 400-800 ng/zone for (1) and (2) and 800-1600 ng/zone for (3). Intermediate precision was below 2 %. LOD and LOQ were 180 and 300 ng/zone for (1), 150 and 210 ng/zone for (2) and 300 and 400 ng/zone for (3), respectively.