The MD-Bio Fentanyl Test Strip is the easiest, fastest and most accurate way to detect trace amounts of fentanyl in packaging, pills, on surfaces and more. Once a test has been run, result interpretation is simple! One or two pink lines will appear on the Fentanyl Test Strip to indicate whether fentanyl has been detected. One line indicates a positive detection for the presence of fentanyl. Two lines indicate a negative detection and that fentanyl has not been detected.