Notes: N-(1-Phenethyl-4-piperidyl)-N-phenethylpropanamide (Item No. 33801) is an analytical reference standard that is structurally similar to known opioids. N-(1-Phenethyl-4-piperidyl)-N-phenethylpropanamide is a byproduct in the synthesis of fentanyl.{61356} This product is intended for research and forensic applications.