**Abstract**

Instrumental methods are widely used for the analysis and stability studies of compounds in bulk and pharmaceutical forms. They vary in their sensitivity, techniques and reagents involved. This chapter will overview those different techniques and the application of the analytical methods. It will also describe how to design and develop simple, sensitive and accurate method for routine quality control of specified compound depending on its molecular structure. Quality control and assurance of the analytical process will be discussed. Furthermore, the chapter will describe a number of factors affecting the chemical and physical stability of Pharmaceutical formulations and how to develop stability-indicating methods to qualify and quantify the drug degradation.

**Keywords:** instrumental, development, quality control, validation, stability
