Butyryl fentanyl-d5 (hydrochloride) (CRM) (Item No. 19390) is a certified reference material intended for use as an internal standard for the quantification of butyryl fentanyl (Item Nos. 19734 | 14728) by GC- or LC-MS. Butyryl fentanyl is categorized as an opioid.1 It is also a potential impurity found in preparations of fentanyl.2 Butyryl fentanyl-d5 is regulated as a Schedule I compound in the United States. This product is intended for research and forensic applications.WARNING This product is not for human or veterinary use.