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. Liq. Chromatogr. Relat. Technol. 34, 805-816 (2011). HPTLC of methyl (1), ethyl (2), propyl (3), and butylparaben (4) on RP-18 first with methanol 60 % and in a second development with methanol 30 %. Quantitative determination by absorbance measurement at 254 nm. The hRf values of parabens (1) - (4) were 57, 47, 37 and 28, respectively. Linearity was between 0.46-2.74 µg/band for (1), 0.50-2.99 µg/band for (2), 0.54-3.24 µg/band for (3) and 0.58-3.49 µg/band for (4). The LOD and LOQ were between 100-370 ng/zone and 200-440 ng/zone, respectively. Relative standard deviation of precision was below 3.5 %. Recovery (by standard addition) was higher than 96.3 % in all cases.

J. Planar Chromatogr. 24, 331-336 (2011). HPTLC of pioglitazone (PIO), metformin (MET), and glimepiride (GLI) in pharmaceutical preparations on silica gel, prewashed with methanol, with acetonitrile - methanol - propanol - ammonium acetate solution 7:2:1:1 in a twin trough chamber saturated for 10 min. Quantitative determination by densitometry at 240 nm. The hRf value was 83, 21, and 89 for PIO, MET, and GLI, respectively. Linearity was in the concentration range of 300-1200 ng/band, 10-40 µg/band and 40-160 ng/band with correlation coefficients of 0.995, 0.996, and 0.998 for PIO, MET, and GLI, respectively. The LOD and LOQ was 57 and 171 ng for PIO, 6 µg and 18 µg for MET, and 12 and 36 ng for GLI. The %RSD for method and intermediate precision was below 2 %. The mean recovery (n = 5) was 98.2-99.5 % for PIO, 98.6-99.3 % for MET, and 98.7-99.7 % for GLI with %RSD between 0.4 and 1.3 %.

J. AOAC Int. 93, 798-803 (2010). HPTLC of atorvastatin calcium on RP-18 with methanol - water 7:3 in a twin-trough chamber saturated for 30 min at room temperature (25 +/- 2 °C) at a relative humidity of 60 +/-5 %. Quantitative determination by absorbance measurement at 246 nm. The hRf value was 62. The LOD and LOQ were 6 and 18 ng/band, respectively. The linearity was between 100 and 800 ng/band. The recovery was between 99.4-100.7 % with %RSD between 0.6-1.4 %. The %RSD of intra-day and inter-day precision (n = 3) was 0.7-1.7 % and 0.6-1.9 %, respectively; the %RSD of repeatability of application (n = 6) was 1.3 %.

Research Journal of Pharmaceutical, Biological and Chemical Sciences 2(1), 6-11 (2011). HPTLC of tolterodine tartarate on silica gel with acetonitrile - water - formic acid 50:50:3 with chamber saturation for 15 min. Quantitative determination by densitometry in absorbance mode at 281 nm. The content of tolterodine tartarate in the formulation was calculated and found to be 99.1 %. The recovery (by standard addition) was between 99.1-100.1 %. LOD was 21 and LOQ 53 ng/zone. The intra-day and inter-day precisions (%RSD) were 0.05 and 0.08 %, respectively.

International Journal of PharmTech Research 3(2), 1174-1178 (2011). TLC of lamotrigine on silica gel with ethyl acetate - chloroform - water 18:6:5. The hRf value was 40. Quantitative determination at 240 nm. The linearity was in the range of 98-590 ng/band with an average recovery of 100.2 %. LOD and LOQ were 44 and 122 ng/zone.

J. Chil. Chem. Soc. 56, 702-705 (2011). HPTLC of lamivudine (1) and tenofovir disoproxil fumarate (2) in bulk drug and pharmaceutical dosage form on silica gel with chloroform - methanol - toluene 4:1:1. Quantitative determination by absorbance measurement at 265 nm. The hRf values of (1) and (2) were 27 and 51, respectively. Linearity was between 60-210 ng/zone for both. LOD and LOQ were found to be 20 and 40 ng/zone for (1) and 30 and 60 ng for (2). The intermediate/interday/intra-day precision was 0.6 % (n=6). Recovery (by standard addition) for (1) and (2) was between 98-102 %. The HPTLC method is suitable for routine analysis of lamivudine and tenofovir in pharmaceutical dosage form.

J. Planar Chromatogr. 24, 541-544 (2011). HPTLC of alpha-asarone (alpha-(1,2,4-trimethoxy-5-[(E)-prop-1-enyl]benzene) in rhizome extracts of Acorus calamus on silica gel with toluene - ethyl acetate 8:3 in a twin-trough chamber with saturation for 30 min. Detection and quantitative determination by densitometry at 254 nm. The linearity was in the range of 200-1000 ng/zone with a correlation coefficient of 0.996. The hRf was 71. LOD and LOQ of the standard were 60 and 173 ng/zone, respectively. Robustness was performed at concentration levels of 200, 400, and 800 ng/zone and the %RSD of peak areas was calculated. The %RSD for robustness analysis was less than 2 % in all cases, which indicated that the experimental procedure was in the range of acceptability as there was not much deviation.