What is the primary purpose of using the Scott Reagent in testing?

The primary purpose of using the Scott Reagent in testing is to confirm the presence of cocaine. Scott Reagent is specifically designed to react with cocaine and its derivatives, producing a characteristic color change that indicates the presence of this substance. This reagent operates through a chemical reaction that results in a blue color, which is a strong indicator of cocaine, making it a valuable tool in the field of narcotics identification.

While the other substances mentioned in the options can also be tested using different methods, they do not produce a response with Scott Reagent. Identifying methamphetamines or heroin typically involves other specific reagents or methods tailored for those drugs. In the case of prescription medications, many different compounds exist, and specialized testing would usually be applied for those substances, rather than relying on Scott Reagent.