Lithium therapy is the gold standard of treatment for patients with Bipolar Disorder. However, despite its effectiveness, it is a potentially hazardous drug requiring regular monitoring of blood levels to ensure toxic levels are not reached. This paper describes the spectrophotometric analysis of Lithium carbonate in solution as a first step in developing a portable home monitoring device for blood lithium analysis.. Using a high-end spectrophotometer, solutions of lithium carbonate (Li2CO3) have been optically fingerprinted. Preliminary measurements indicate that the ultraviolet region shows a strong distinction between different lithium concentrations. Utilizing second derivative absorption curves, the region of 220 nm to 230 nm demonstrated the ability to differentiate between concentrations representing those found in patients. Furthermore, the method could determine to within a 1–6% accuracy whether an unknown solution of Li2CO3 is either inside or outside the high-end of the therapeutic limit.