J. Planar Chromatogr. 22, 49-53 (2009). TLC of geranylgeraniol and plaunotol on silica gel with chloroform - n-propanol 24:1 or 48:1, or with ethyl acetate, in saturated chambers. Quantitative determination by absorbance measurement at 210 nm. Detection of plaunotol by exposure to iodine vapor for 10 min. The acyclic diterpenoid plaunotol present in Croton stellatopilosus leaves is a hydroxylation product, catalyzed by the enzyme geranylgeraniol-18-hydroxylase. The activity of the enzyme in cell-free extracts of C. stellatopilosus leaves was previously reported. In this study a new mobile phase (ethyl acetate) was used for determination of geranylgeraniol-18-hydroxylase in the 20,000 g and 100,000 g precipitates of the crude extracts. In addition ethyl acetate successfully separated plaunotol from various cytochrome P-450 inhibitors (ancymidol, metyrapone, and miconazole) frequently used for biochemical characterization of the hydroxylase enzymes.

J. Planar Chromatogr. 22, 83-88 (2009). TLC of isoniazid, pyrazinamide, ethambutol, and aminosalicylic acid on RP-18 in a horizontal chamber at 20 °C with acetonitrile - water 3:7. The mobile phase was modified by adding copper(II) chloride to the mixture at a constant concentration of 0.05 M. Detection under UV light at 254 nm. Quantitative determination by absorbance measurement in the range 200 - 700 nm with a TLC scanner equipped with a diode-array detector.

J. Planar Chromatogr. 22, 201-206 (2009). TLC of ambroxol hydrochloride and doxycycline hyclate on silica gel with ethyl acetate - ethanol - glacial acetic acid - water 90:40:5:10 with chamber saturation for 1 h. Detection under UV 254 nm. Quantitative determination by absorbance measurement at 254 nm for ambroxol hydrochloride and 270 nm for doxycycline hyclate.

J. Planar Chromatogr. 22, 191-196 (2009). TLC of pioglitazone hydrochloride ((+/-)-5-{p-[2-(5-ethyl-2-pyridyl)ethoxy]benzyl}-2,4-thiazolidinedione hydrochloride and degradation products (after acid and alkaline hydrolysis, oxidation, photochemical and thermal treatment) on RP-18 with acetone - acetic acid - water 40:10:1 in a twin trough chamber saturated for 30 min at room temperature (25 +/- 2 °C). Quantitative determination by absorbance measurement at 225 nm. The limit of detection and quantification was 47 and 141 ng/zone, respectively.

60th Indian Pharmaceutical Congress PA-214 (2008). HPTLC of cinnamic acid (in plant raw material, herbal extracts and pharmaceutical dosage forms) on silica gel with chloroform - methanol 4:1 in a saturated twin trough chamber at room temperature (25 °C). Quantitative determination by absorbance measurement at 277 nm. The hRf value for cinnamic acid was 50. The method was linear in the range of 700-1400 ng/spot.

J. Chromatogr. B 877 (29), 3719-3723 (2009). HPTLC of gemifloxacin mesylate in human plasma, extracted with chloroform - acetic acid 59:1, on silica gel with ethyl acetate – methanol - ammonia 8:4:3. The hRf value of gemifloxacin mesylate was 33. Quantification by densitometry at 254 nm. The calibration curve was established in the range of 50 to 600 ng/spot. Recovery of gemifloxacin mesylate was between 80.0 and 86.2 %. The stability of gemifloxacin mesylate in plasma was confirmed with samples submitted to three cycles of freeze–thawing at -20 °C, and with samples stored on the bench for 12 h.

60th Indian Pharmaceutical Congress PA-226 (2008). HPTLC of olmesartan medoxomil (an angiotensin-II antagonist) on silica gel with toluene - acetonitrile - methanol - ethyl acetate - acetic acid (mobile phase ratio not specified by the authors). The hRf value was 56. Quantitative determination by absorbance measurement at 262 nm. The linearity was between 300-800 ng/spot. The method was suitable for separation of olmesartan medoxomil from degradation products obtained by forced stress conditions (acid, alkali, peroxide, light, heat).

Abstract No. F-277, 61st IPC (2009). HPTLC of theobromine in different extracts of tea (Camelia sinensis) on silica gel with ethyl acetate - methanol 27:3. Quantitative determination by absorbance measurement at 274 nm. The maximum content of theobromine in tea samples was 2.3 %. Linearity was in the range of 3-15 µg/zone. The limit of detection and quantification was 30 and 140 ng/spot, respectively.