International Seminar on Herbal Drug Research, PN-008 (2009). HPTLC of withaferin-A from Nicandra physaloides on silica gel with toluene - ethyl acetate - formic acid 10:3:1. The hRf value was 14. Quantitative determination by absorbance measurement at 213 nm.

J. Planar Chromatogr. 23, 141-147 (2010). HPTLC of p-aminobenzoic acid on silica gel (prewashed with the mobile phase) with diethyl ether - cyclohexane 5:1 in an unsaturated chamber. Quantitative determination by absorbance measurement at 270 nm. Detection by automatic spraying the following reagent solutions: 0.1 mol/L sodium nitrite solution, 0.1 mol/L hydrochloric acid, 0.03 mol/L ethanolic 8-hydroxyquinoline solution, and 10% sodium hydroxide solution. For each solution 2 spraying cycles were applied. After drying quantitative determination by densitometric scanning at 500 nm. Measured before derivatization at 270 nm calibration of p-aminobenzoic acid was perfomed between 50-1600 ng per spot. LOD was 170 ng/spot (calculated) and 50 ng/spot (estimated visually). LOQ (calculated) was 510 ng/spot. The correlation coefficient r was 0.9936 (peak area) and 0.9866 (peak height); the linear range was 200-1800 ng/spot. Measured at 500 nm after derivatization, LOD was 290 ng/spot (calculated) and 50 ng/spot (estimated visually). LOQ (calculated) was 870 ng/spot and 200 ng per spot (estimated visually). The correlation coefficient r was 0.9815 and 0.9538.

czern and Brassica nigra L. Asian J. Chem. 22(7), 5349-5354 (2010). An HPTLC method is reported for estimation of sinigrin from seeds of Brassica juncea and Brassica nigra (Cruciferae). HPTLC of methanolic seed extracts on silica gel with ethyl acetate - methanol - water 6:2:1. Densitometric evaluation at 230 nm. The method was linear in the range of 400-1200 ng/band. Amounts of 0.43 and 1.55 % sinigrin were found in Brassica juncea and B. nigra, respectively. The method is suitable for routine quality control of herbal raw material.

J. Liq. Chromatogr. Relat. Technol. 33, 1005-1012 (2010). HPTLC of lipids (free sterols, free fatty acids, triacylglycerols, methyl esters, and steryl esters) on silica gel (plates with concentration zone) with petroleum ether - diethylether - glacial acetic acid 80:20:1. Detection by spraying with 5 % ethanolic phosphomolybdic acid reagent and heating for 10 min at 110 °C. Quantitative densitometric analysis was performed at 610 nm.

International Journal of Pharmaceutical Sciences Review and Research 2(2), 35-39 (2010). TLC on silica gel with methanol - chloroform 1:6. The hRf value was 38 and 68 for ramipril and telmisartan respectively. Densitometric evaluation at 210 nm. The method was linear in the range of 300-3000 ng/band and 500-4000 ng/band for ramipril and telmisartan respectively. The recovery was 98-102 %. The sample was subjected to different stress conditions (acid, base, oxidative, heat, photolytic) and all the degradation products were well separated from drug.

J Young Pharm 1(3), 259-263 (2009). A validated HPTLC method is described for simultaneous estimation of amlodipine besylate and telmisartan in dosage form. HPTLC on silica gel with tetrahydrofuran - dichloroethane - methanol - 25 % ammonia solution 60:20:10:4. The hRf value of amlodipine besylate was 45 and of telmisartan 22. Densitometric evaluation at 326 nm. Linearity was in the range of 1200-7200 ng/band for telmisartan and 400-1400 ng/band for amlodipine besylate. The limit of detection was 149 ng/zone and 53 ng/zone for telmisartan and amlodipine besylate, respectively. The limit of quantification was 453 ng/zone for telmisartan and 161 ng/zone for amlodipine besylate. The recovery was between 100.4 and 100.8 %.

Eurasian J. Anal. Chem. 5(1), 25-27 (2010). An HPTLC method is reported for estimation of levodopa in seeds of Mucuna pruriens and its herbal formulation. HPTLC on silica gel with n-butanol - glacial acetic acid - water 5:1:4. Densitometric evaluation at 280 nm. The hRf value of levodopa was 39. The method was linear in the range of 100-1000 ng/band. The method is suitable for estimation of levodopa in herbal formulation.

International Journal of Green Pharmacy 3 (1), 47-17 (2009). HPTLC of caffeine on silica gel with ethyl acetate - methanol 9:1. Densitometric quantification at 274 nm. The method was linear in the range of 2-14 µg/band. The sample extracted with 5 % diethyl amine in water gave the maximum yield of caffeine (2.1 %). The proposed chromatography gave the best resolution with caffeine at an hRf value of 40. The method can be used for quality control of tea samples in respect of caffeine contents.