para-Fluorofentanyl-d5 (hydrochloride) (CRM) (Item No. 19946) is intended for use as an internal standard for the quantification of para-fluorofentanyl (Item Nos. 19735 | 15496 | 39713) by GC- or LC-MS. para-Fluorofentanyl is categorized as an opioid.1 para-Fluorofentanyl has antinociceptive activity in rats.2 It has been found in samples seized by law enforcement.3 para-Fluorofentanyl-d5 is regulated as a Schedule I compound in the United States. para-Fluorofentanyl-d5 (hydrochloride) (CRM) (Item No. 19946) is provided as a DEA exempt preparation. This product is intended for research and forensic applications.WARNING This product is not for human or veterinary use.