An opioid analgesic and fentanyl analog with about one fifth the potency of fentanyl. Furanyl fentanyl, or Fu-F, is sold on the illicit market as a designer drug or in combination with heroin. This Certified Spiking Solution® is suitable for use as starting material in calibrators and controls for fentanyl LC/MS or GC/MS testing methods in clinical toxicology, urine drug testing, prescription monitoring, or forensic analysis applications.