Analytical chemistry techniques are routinely used in many areas of medicine. When your blood is drawn, for example, the doctors use techniques borrowed from analytical chemistry to determine levels of several analytes in your body, including cholesterol, vitamins, glucose, and white blood cells. Analysis of tissue samples and other biological fluids is also based on analytical techniques. Other examples of medically related applications include tests for illegal drugs and steroids, glucose sensors used by diabetic patients, or to check for toxic substances in your body if you are exposed to hazardous chemicals.