Purpose:**  
The cocaine test is designed to detect the presence of cocaine or its metabolites in the body. It is commonly used for drug screening in various contexts, including workplace testing, legal and forensic investigations, and medical diagnostics.

- **False Positives:** Certain medications or substances might cause false positives, though rare. Confirmatory tests (e.g., GC-MS) are usually employed after an initial positive result to rule out false positives.
- **False Negatives:** If the test is conducted outside the detection window or if the sample is tampered with, a false negative might occur.

Normal Range
- **Negative:** No detectable level of cocaine or its metabolites.
- **Positive:** Presence of cocaine or its metabolites above the cut-off level, indicating recent use.

 Interpretation
- **Negative Result:** Indicates no recent use of cocaine or below-threshold levels of the drug/metabolites.
- **Positive Result:** Indicates recent use of cocaine. The presence of metabolites like benzoylecgonine is typically measured to confirm cocaine usage.

- **Urine:** Most commonly used due to ease of collection and longer detection window.
- **Blood:** Used for detecting recent use, as cocaine and its metabolites are detectable in blood for a shorter period.
- **Saliva:** Non-invasive and reflects recent use.
- **Hair:** Provides a longer detection window (up to 90 days) but is less common.