The College of Pharmacy at  University of Basrah organized a seminar about the effect of the pH value of the moving medium on the electivity in the high pressure chromatography method . The seminar was presented by of Dr. Muhammad Starr ,  discussed and explained the mechanism of action of the HPLC device. This device is a high-pressure liquid chromatography device, and its various and pharmaceutical applications, as it included a reference to the standards required to be met when using this device, including optional, efficiency, clarity and others. The seminar also  illustrated different types of stationary phase that are used in this device and the mechanisms of action for each. This topic   aims to show the importance of choosing the PH value of each drug and its dependence on its ionic nature.