What is the primary purpose of using presumptive tests in forensic science?

The primary purpose of using presumptive tests in forensic science is to suggest the possible presence of a substance. Presumptive tests are designed to indicate whether a particular class of substances might be present, often through color changes or other observable reactions. These tests provide initial screening results that can guide further investigation but do not definitively identify or quantify the substance.

For instance, in drug analysis, a presumptive test may show a color change indicating the presence of a narcotic, but it does not confirm the substance's identity. As such, while they are valuable for narrowing down possibilities and directing further testing, they are not meant to provide conclusive evidence or replace more definitive testing methods, which would be necessary to confirm the findings. This understanding is crucial in forensic science to avoid making premature conclusions based solely on presumptive test results.