var hirsuta. 62nd Indian Pharmaceutical Congress Abstract No. F-238 (2010). TLC of the two marker compounds bebeerine and oleanolic acid from the roots of Cissampelos pareira Linn. on silica gel with toluene – ethyl acetate – diethylamine 7:2:1 for bebeerine and toluene – ethyl acetate – formic acid 70:30:3 for oleanolic acid. The hRf value was 20 (bebeerine) and 56 (oleanolic acid). Quantitative determination by absorbance measurement at 254 nm and under visible light after spraying with dragendorff’s reagent (bebeerine) or anisaldehyde sulfuric acid reagent (oleanolic acid).

Acta Chromatographica 21(2), 203-215 (2009). HPTLC of commercial products containing Heterotheca inuloides, Citrus aurantium, Peumus boldus, Equisetum arvense, Eucalyptus globulus, Ginkgo biloba, Mentha piperita, Aloe vera, Salvia officinalis , and Cassia senna on silica gel with different mobile phases. The mobile phase for aloin, boldine, chlorogenic acid, rutin, kaempferol, caffeic acid, and quercetin was ethyl acetate – methanol – water 100:17:13; for menthol, cineole, menthone, alpha- and beta-thujone, geraniol, linalyl acetate and linalool it was toluene – ethyl acetate 93:7; for ginkolide B toluene – ethyl acetate – acetone – methanol 50:25:25:3; and for sennoside B ethyl acetate – formic acid – acetic acid – water 100:11:11:27. Detection with natural products reagent, anisaldehyde reagent or Liebermann-Burchard reagent. We found that in only 20 % of the 40 commercial products analysed the chromatographic characteristics of the respective plants matched those of the specific respective marker compounds. This highlights a problem arising from the lack of regulation of these products, and emphasizes the need to develop simple and reliable analytical methods like TLC methods that can be performed in any laboratory for the purpose of quality control of dietary supplements or commercial herbal products sold in Mexico.

International Journal of Pharma and Bio Sciences 1(1), 1-3 (2010). Shade dried aerial parts of the plant were extracted with acetone (A) and methanol (B) and the solvent was removed to get the crude extract. Extract A was further fractioned over silica gel (60-120) by eluting with n-hexane (C) and n-hexane – acetone 9:1( D) . TLC of all fractions on silica gel with n-hexane – ethyl acetate. Quantitative determination by absorbance measurement at 258 nm. The linearity was in the range of 1-5 µg/band. The amount of santonin found in different fractions of the acetone extract was 31.3 mg/g (A), 40.7 mg/g (B), 1.9 mg/g (C), and 20.9 mg/g (D).

J. Planar Chromatogr. 24, 160-165 (2011). HPTLC of venlafaxine hydrochloride in bulk and formulations on silica gel with butanol - acetic acid - water 3:1:1. Quantitative determination by densitometry in absorbance mode at 284 nm. The hRf value was 58. Linearity was between 100 and 600 ng/zone. The limit of detection and quantification was 39 and 131 ng/zone, respectively. The repeatability and the intermediate precision (%RSD, n = 6), were between 0.3-0.7 % and 0.6-0.9 %, respectively. The recovery was between 99.1 and 101.7 %.

International Journal of PharmTech Research 2(3), 1376-1379 (2010). TLC of brimonidine tartrate on silica gel with methanol - 25 % ammonia 40:1 with chamber saturation for 20 min. The hRf value was 52. Quantitative determination by densitometry in absorbance mode at 250 nm. The method was linear in the range of 200-1200 ng/band. The intra-day and inter-day precision, as %RSD, was in the range of 0.7-1.8 % and 0.9-1.8 %, respectively. The mean recovery (by standard addition) was 99.7 %.

J. Planar Chromatogr. 24, 99-104 (2011). TLC of candesartan and losartan on silica gel with 1,4-dioxane - hexane - 99 % formic acid 50:50:1. Quantitative determination by densitometry at 258 nm for candesartan and at 243 nm for losartan, videoscanning at 254 nm for both drugs. The hRf value for candesartan was 47 and for losartan 35. Linearity was between 0.2 and 1.4 µg/band for both drugs with correlation coefficients of 0.9997 and 0.9981 for candesartan, and 0.9986 and 0.9982 for losartan, for densitometry and videoscanning, respectively. Robustness (%RSD, peak area) was less than 1.9 and 0.8 % for candesartan, and 2.2 and 0.9 % for losartan in densitometry and videoscanning, respectively. The repeatability and intermediate precision (%RSD, two lowest amounts) were less than 3.6 and 4.7 % for candesartan and less than 4.7 and 5.3 % for losartan. Mean recoveries for candesartan were 103.8-104.9 % for densitometry and 99.2-100.7 % for videoscanning; for losartan the respective values were 100.8-105.4 % and 98.6-99.2 %.

J. Planar Chromatogr. 24, 232-235 (2011). HPTLC of darunavir ethanolate in tablets on silica gel, prewashed with methanol, with toluene - ethyl acetate - methanol 7:2:1 in a twin-trough chamber lined with filter paper and saturated with mobile phase for 30 min at room temperature (25 +/- 2 °C). Quantitative determination by densitometry in absorbance mode at 267 nm. The hRf of darunavir ethanolate was 47. Linearity was between 250 and 1750 ng/band with r = 0.9994. The limits of detection and quantification were 15 and 46 ng/band, respectively. The intra-day and inter-day precision was (%RSD, n = 6) between 0.5-0.9 % and 1.1-1.3 %. Recovery (n = 6) was 99.3-101.2 %.

Planta Med. 75, 12-17 (2009). HPTLC of swertiamarin and the ethyl acetate extract of Enicostemma axillare on silica gel with ethyl acetate - butanol 1:1 in a twin trough chamber. Quantitative determination by densitometric absorbance measurement at 254 nm.