CBS 100, 13-15 (2008). HPTLC of caffeine on silica gel with ethyl acetate - methanol - 25 % ammonia 90:15:1 (for samples of energy drinks) or chloroform - ethanol - 37 % acidic acid - acetone - water 54:27:10:2:2 (for samples of headache tablets). Detection under UV 254 nm. Quantitative determination by absorbance measurement at UV 274 nm. Automated online extraction with an HPTLC/MS interface connected to a ESI mass spectrometer. Without any internal standard the caffeine mass signal was recorded in the selected ion monitoring mode at m/z 195 [M+H]+. The method was validated. Repeatability was 5.6 % (%RSD, n=6) and reproducibility of the plate mean value was 1.5 % (%RSD, n=3).

Asian J. Chem. 20(7), 5514-5518 (2008). HPTLC of dutasteride on silica gel with toluene - ethyl acetate - acetic acid 14:6:1. Absorbance measurement at 210 nm. The method was linear in the range of 50-500 µg/µL. Recovery was 99.3-99.5 %. The method was suitable for routine quality control.

Indian J. Pharma Educ. Res. 42(1), 32-35 (2008). HPTLC of metoprolol succinate on silica gel with toluene - methanol - triethylamine 30:50:3. Quantitative determination by absorbance measurement at 274 nm. The hRf value was 40. The method was linear in the range of 5-10 ng/spot. The limit of detection and quantification was 430 ng/spot and 1310 ng/spot respectively. The method was suitable for routine quality control.

Food Chemistry 113, 640-644 (2009). HPTLC of curcumin (1), demethoxycurcumin (2), and bisdemethoxycurcumin (3) from the rhizomes of Curcuma longa on silica gel with chloroform – methanol 24:1. Quantitative determination by absorbance measurement at 425 nm. The hRf values of (1), (2), and (3) were 66, 48, and 30, respectively. Selectivity regarding matrix was given. Recovery was 98.7 % for (1), 96.3 % for (2), and 97.2 % for (3). The limit of detection for (1), (2), and (3) was 0.1 µg/spot. The linear regression equation was y=4447.26 + 61.993X for (1), y=1089.881 + 70.003X for (2), and y=2611.84 + 51.565X for (3).

Asian J. Chem. 19(6), 4183-4187 (2007). HPTLC of atenolol and indapamide in tablet formulation on silica gel with toluene - ethanol - acetone - acetic acid 70:25:30:3. Quantitative determination by absorbance measurement at 266 nm. The hRf value of atenolol and indapamide was 21 and 74, respectively. The linearity range was 3.8-10.9 ng/spot and 0.2-0.6 ng/spot for atenolol and indapamide respectively. The recovery was in the range of 98.7-100.1 % for both compounds.

60th Indian Pharmaceutical Congress PA-200, (2008). HPTLC of fluoxetine HCl and olanzapine on silica gel with acetone - methanol - triethylamine 10:6:1. Quantitative determination by absorbance measurement at 235 nm. The method was linear in the range of 300-1000 ng/spot for fluoxetine HCl and 50-500 ng/spot for olanzapine respectively. The method was suitable for quality control of combined dosage form.

Asian J. Chem. 19(5), 3627-3632 (2007). TLC of simvastatin and ezetimibe on silica gel with ethyl acetate - chloroform 4:1. Quantitative determination by absorbance measurement at 220 nm. The hRf value of simvastatin was 76 and of ezetimibe 89. Linearity was between 600 and 1400 µg/mL for simvastatin and ezetimibe. The recovery (by standard addition method) was in the range of 99.7 and 99.6 % for both drugs. The proposed method is precise, accurate and can be used for routine analysis of simvastatin and ezetimibe in tablets.

Anal. Chem. 75, 118-125 (2003). Online TLC separation and electrospray mass spectrometry (TLC/ESI-MS) by direct linking of a commercial overpressure TLC instrument, OPLC 50, and a Q-TOF mass spectrometer. Separation on silica gel with dichlormethane - methanol - water 60:35:8. A sensitivity of 5 pmol of glycosphingolipid was readily demonstrated for TLC/ESI-MS and 20 pmol for TLC/ESI-MS/MS production scanning to derive the saccharide sequence and long chain base/fatty acid composition of the ceramide. Initial preconditioning of TLC plates is necessary to achieve high sensitivity detection by reducing chemical background noise. Plates can be used repeatedly (at least 10 times) for analysis, although this may result in a minor reduction in TLC resolution. Following solvent development, separated components on the TLC plates can be detected in the conventional way by nondestructive staining or UV absorption or fluorescence and can be stored for on-line TLC/ESI-MS analysis at a later stage without reduction in mass spectrometric detection sensitivity and chromatographic resolution. Aspects for further improvement of OPLC instrumentation include use of narrower TLC plate dimensions and refined design of the eluate exit system.