Experimental design in reversed-phase high-performance liquid chromatographic analysis of imatinib mesylate and its impurity

For the determination of the optimal RP-HPLC chromatographic conditions for the separation of imatinib mesylate and its impurity STI 509-00 experimental design 24 was applied. All the factors that affect imatinib mesylate/STI 509-00 separation, as well as their mutial interations were investigated. Methanol and triethylamine content in the mobile phase, pH of the mobile phase and column temperature were independent variables or factors to be investigated in two levels: “low” and “high”. Capacity factor was chosen as a dependent variable. From the experimentally determined capacity factor values, it was defined the factors that affect to chromatographic system the most. Applying response surface methodology the appropriate graphs were constructed from experimental points and optimal chromatographic conditions for the separation were defined. Optimal conditions for the separation of imatinib mesylate and STI 509-00 were obtained using X Terra 150 mm×4.6 mm, particle size 5 μm column at 25 °C. Mobile phase consisted of 250 ml of methanol, 740 ml of water and 10 ml of triehylamine. pH of water phase was adjusted to 2.4 with 85% orthophosphoric acid and than methanol was added.