Abstract No. F-262, 61st IPC (2009). HPTLC of L-dopa on silica gel with n-butanol - water - actic acid 4:1:1. The hRf was 37. Detection by spraying with 0.5 % ethanolic ninhydrin solution, followed by heating at 120 °C for 2 min. Quantitative determination by absorbance measurement at 520 nm. The method was linear in the range of 600-1400 ng/band.

J. Planar Chromatogr. 22, 367-369 (2009). HPTLC of triterpenoids (alpha- and beta-amyrin, oleanolic acid) on silica gel prewashed with methanol and dichloromethane, with dichloromethane - ethyl acetate 37:3. in a horizontal chamber saturated for 15 min. Detection by spraying with 8 % sulfuric acid in ethanol and heating at 105 °C for 3 min. Evaluation in daylight and under UV 366 nm. Quantitative determination by absorbance measurement at 520 nm.

Bio. Chromatogr. 21(10), 1064-1068 (2008). Indirect chiral TLC separation of penicillamine (3,3-dimethylcysteine) enantiomers after derivatization with Marfey's reagent (FDNP-Ala-NH2) and two of its structural variants, FDNP-Phe-NH2 and FDNP-Val-NH2 on silica gel and RP-18 with phenol - water 3:1 and solvent combinations of acetonitrile and triethylamine phosphate buffer. The methods were applied for determination of the enantiomeric impurity of l-penicillamine, d-penicillamine, and pharmaceutical formulations of d-penicillamine.

Abstract No. F-18, 61st IPC (2009). HPTLC of levocetirizine dihydrochloride and montelukast sodium in bulk and tablet dosage formulation on silica gel with toluene - ethyl acetate - methanol - 25 % ammonia 5:14:5:2. Both drugs were well resolved with hRf values of 31 for levocetirizine and 44 for montelukast. Quantitative evaluation at 231 nm. The method was linear in the range of 500-2500 ng/band for levocetirizine and 1000-5000 ng/band for montelukast. Both drugs were also analysed by HPLC on RP18 column and results were comparable with HPTLC.

Abstract No. C-161, 61st IPC (2009). An HPTLC method is reported for estimation of andrographolides bitter principles in Andrographis paniculata, popularly known as kalmegh. HPTLC of methanolic and water extracts on silica gel with chloroform - methanol 7:1 in a saturated twin trough chamber. Quantitative evaluation by absorbance measurement at 231 nm. The method was found to be linear in the range of 1-5 µg/band. Both extracts were found to contain andrographolides. Maximum yields of andrographolides were observed in extracts prepared by refluxing.

J. Liq. Chromatogr. Relat. Technol. 33, 423-430 (2010). HPTLC of olmesartan and zidovidine on silica gel with ethyl acetate - methanol - acetic acid 160:40:1 in a twin-trough chamber saturated for 10 min. Quantitative determination by densitometric scanning at 269 nm. The linearity range was 80-600 ng/zone. LOQ was 80 ng/zone, the correlation coefficient 0.9900 and 0.9820. Recovery was 90.1 and 79.6 %. The accuracy and precision of the method were determined by repeatability (intra-day) and intermediate precision (inter-day) for the set of quality control samples (low, mid, high) in replicate. The results revealed excellent intra- and inter-day accuracy and precision of the method, which was within the acceptable limit (accuracy (% RE) 11.89 and 6.76 (low), 2.53 and 3.83 (mid), and 0.65 and 7.14 (high); inter-day precision (CV): 3.29 and 3.00 (low), 1.02 and 1.51 (mid), and 1.11 and 0.69 (high); intra-day precision: 2.59 and 2.86 (low), 1.07 and 1.13 (mid), and 1.04 and 0.72 (high) - after LLE and SPE, respectively).

Drug Development and Industrial Pharmacy 35, 440-448 (2009). TLC of tacrolimus on silica gel with toluene - acetonitrile - glacial acetic acid 60:40:1. For quantitative evaluation the plate was derivatized with anisaldehyde sulfuric acid reagent and scanned at 675 nm. Using this method a compact spot was obtained at an hRf value of 40. The linearity range was 100-800 ng/band. The method is suitable for routine analysis of formulations.

International Journal of ChemTech Research 2(2), 851-855 (2010). Defatted powdered roots of Helicteres isora (Sterculiaceae) were extracted with ethyl acetate. TLC on silica gel with toluene - acetone - formic acid 25:5:2. The hRf value was 43. Densitometric evaluation at 540 nm. The method was linear in the range of 100-500 ng/band. Recovery was 98.4-99.9 %.