The Lithium (Li) test using Atomic Absorption Spectrophotometer in Flame and GFA (Graphite Furnace Atomization) modes is primarily used to determine lithium levels in blood or other biological fluids. This test is essential for patients undergoing lithium treatment, such as those with bipolar disorder, as it helps monitor the effectiveness of the treatment and prevent toxicity. The test is performed by drawing a blood sample, which is then analyzed using two techniques: Flame and GFA, ensuring accuracy and reliability of the results. Normal lithium levels in blood range from 0.6 to 1.2 mmol/L, and it is recommended to be monitored under medical supervision to ensure proper dosage adjustment. The results assist doctors in making effective treatment decisions and providing optimal care for patients.