Abstract CP-53, IPC (2005). HPTLC of andrographolide and wedelolactones in several market samples on silica gel with toluene - acetone - formic acid 9:6:1. Quantitative determination by absorbance measurement at 254 nm. The hRf value of andrographolide was 52 and of wedelolactone 58. Linearity was obtained between 200-400 ng/spot and 120-200 ng/spot respectively with recovery rates of 98.1-106.7 %. A complex coumarin from Eclipta alba was used as marker.

J. Planar Chromatogr. 18, 240-243 (2005). TLC of twenty-one N-benzyl-2-azaspiro[4.4]nonane- and [4.5]decane-1,3-dione derivatives on RP-18 with a mixture of n-propanol and TRIS buffer (pH 7.0) in a chamber saturated for 30 min. Detection under UV light at 254 nm. Examination of chromatographic behavior revealed a linear correlation between RM values and the concentraton of n-propanol in the mobile phase.

J. Planar Chromatogr. 18, 207-211 (2005). HPTLC of rifampicin and isoniazid on silica gel (prewashed with methanol) in a horizontal chamber with ethyl acetate - methanol - acetone - acetic acid 5:2:2:1 after pre-saturation for 30 min. Densitometric evaluation by absorbance measurement at 345 nm for rifampicin and at 270 nm for isoniazid. For isoniazid and rifampicin CV was 0.42 and 0.16 %, relative standard error 0.01 and 0.13 %, and recovery 98.9 and 102.5 %, respectively.

J. Sep. Sci. 28 (6), 575-580 (2005). HPTLC of pentoxifylline and related substances, impurities of reaction partners and side reaction products, on LiChrospher RP18 with acetone - chloroform - toluene - dioxane 2:2:1:1. Quantitative determination at 275 nm. Linearity (r2= 0.997), recovery (86.5-115.5 %) and determination limit (0.1-0.6 %) were evaluated and found to be satisfactory. This method enables monitoring of the synthesis as well as purity control of pentoxifylline-containing raw materials and pharmaceuticals.

J. Pharm. Biomed. Anal 37 (5), 971-977 (2005). HPTLC of colchicine in Colchicum autumnale (meadow saffron) extracts, on silica gel with chloroform - acetone - diethyl amine 5:4:1. Quantification in absorbance mode at 350 nm. The peaks were optimized in area and shape by varying 4 scanning parameters (slit width and height, number of measurements and scanning speed). Calibration range of pure colchicine was 50-600 ng/mL. This method can be used in pharmaceutical industry for quick and accurate quantitative determination of colchicine because it eliminates the inteferences given by other bioactive or degradation compounds. The method was validated regarding linearity, accuracy, fidelity, and sensitivity.

J. Sep. Sci. 29, 2716-2724 (2006). HPTLC of alfuzosin hydrochloride subjected to stress conditions (alkaline, acidic, oxidative, thermal, and photo-degradation) on silica gel with methanol - ammonia 125:3. Quantitative determination by absorbance measurement at 245 nm. Linearity of determination of alfuzosin is between 0.5 and 7.0 µg and its average percentage recovery is 98.5 - 101.8 %. The drug is well separated from its degradation products upon applying the two methods.

Anal. Sci. 22, 743-745 (2006). HPTLC of gatifloxacin and ornidazole on silica gel with n-butanol – methanol 8:1 and 1 drop ammonia with chamber saturation for 45 min. Quantitative determination by absorbance measurement at 302 nm. Linearity of determination of gatifloxacin is 100 – 500 ng and of ornidazole 250 – 1250 ng, with a correlation coefficient of more than 0.9850. The intra-day and inter-day coefficients of variation are found to be in the range of 0.68 - 2.58 % and 0.37 - 3.62%, respectively.

Indian J. Pharm. Sci. 68 (6), 793-796 (2006). HPTLC of atorvastatin calcium and ezetimibe in combined dosage form on silica gel with chloroform - benzene - methanol - acetic acid 60:30:10:1. Detection under UV 250 nm.The method was validated in terms of linearity, accuracy, precision and specificity.The calibration curve was found to be linear between 0.8 and 4.0 µg/spot for atorvastatin calcium and 0.1 and 1.0 µg/spot for ezetimibe. The limit of detection and the limit of quantification for atorvastation calcium were found to be 170 ng/spot and 570 ng/spot, respectively, and for ezetimibe 20 ng/spot and 70 ng/spot, respectively.The recovery was in the range of 99.9 - 102.7 %.