**Abstract**

The most important objectives frequently found in analytical and bioanalytical chemistry involve advancement of analytical techniques and its application to relevant medical/clinical problems. Keeping in view to these aspects, the present chapter is primarily focused on the development of advanced analytical techniques applied in the medical field. For example, N-acetyl-beta-D-glucosaminidase (NAG) enzyme is a specific biomarker of acute kidney injury. A biomarker is an entity that is purposely measured and estimated as an indicator of normal biological process, pathogenic process, or pharmacological responses to a therapeutic intervention. Hence, successive measurements of urinary NAG may enhance its clinical use as an indicator of ongoing tubular injury. Hence, in order to obtain information for selective monitoring of biomarker, the development of a practical and valid analytical method is important. Experimentation is driven by the need to know more about the medical effects and safety features of the biologically active analyte. It is therefore more important to evaluate the information that is already available for that particular analyte and to quantify the level of uncertainty for the proposed technique.

**Keywords:** analytical, bioanalytical, biomarker, clinical, medical, N-acetyl-beta-D-glucosaminidase
