Acetyl fentanyl-13C6 (hydrochloride) (Item No. 25557) is an analytical reference material intended for use as an internal standard for the quantification of acetyl fentanyl (Item Nos. ISO00128 | ISO60128) by GC- or LC-MS. Acetyl fentanyl is categorized as an opioid.1 Acetyl fentanyl 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.