TDF and ETB gave sharp and well defined peaks at Rf 0.41 and 0.68, respectively, when scanned at 276 nm. The results

are shown in Table 1 indicate that there was no interferences from ZD1839 cell line the excipients commonly present in the tablets. The 10 mg of TDF and ETB were separately dissolved in 10 ml methanolic solution of 1 M HCl and 1 M NaOH. These solutions were kept for 8 h at room temperature in the dark in order to exclude the possible degradative effect of light. The 1 ml of above solutions were taken, neutralised and diluted up to 10 ml with methanol. The resultant solution were applied on TLC plates in triplicates (6 μl each, i.e. 600 ng/spot). The chromatograms were run as described in Section 2.2. The 10 mg of TDF and ETB were separately dissolved in 10 ml of methanolic solution of hydrogen peroxide (10%, v/v). The solutions were kept for Tyrosine Kinase Inhibitor Library 8 h at room temperature in the dark in order to exclude the possible degradative effect of light. The 1 ml of above solutions were taken and diluted up to 10 ml with methanol. The resultant solutions were applied on TLC plate in triplicate (6 μl each, i.e. 600 ng/spot). The chromatograms were run as described in Section 2.2. TDF 10 mg and ETB 10 mg were stored at 55 °C for 3 h in oven separately. They were transferred to 10 ml volumetric flask containing

methanol and volume was made up to the mark. 0.6 μl (600 ng/spot) was applied on TLC plate in triplicate and chromatogram were run as described in Section 2.2. The 10 mg of TDF and ETB were dissolved in 10 ml of methanol separately. The solutions were kept in the sun light for 8 h. The 1 ml of above solutions were taken and diluted up to 10 ml with methanol. The resultant

solutions were applied on TLC plate in triplicate (6 μl each, i.e. 600 ng/spot). The chromatograms were run as described in Section 2.2. Initially, toluene: ethyl acetate: methanol in the ratio 4:2:2 (v/v/v) was tried for for both drugs simultaneously. The spots were not developed properly and dragging was observed. Then, toluene: ethyl acetate: methanol in the ratio of 6:4:3 (v/v/v) was tried. The developed spots were diffused. To the above mobile phase, 0.2 ml acetic acid was added. Both the peaks were symmetrical in nature and tailing was observed. To improve resolution, the volume of acetic acid was increased to 0.4 ml. Finally, mobile phase consisting of toluene: ethyl acetate: methanol: acetic acid (6: 4: 3:0.4, v/v/v) gave good resolution. Both the peaks were symmetrical in nature and no tailing was observed when plate was scanned at 276 nm. The chamber was saturated with the mobile phase for 20 min at room temperature and plates were activated at 110 °C for 5 min to obtain well defined spots. Linearity responses for TDF and ETB were assessed in the concentration ranges 150–1500 ng/spot and 100–1000 ng/spot, respectively. The linear equations for the calibration plots were Y = 2.6712X + 1161.1 and Y = 8.0837 + 25.859, with correlation coefficient (r) being 0.9998 and 0.