Valeryl fentanyl carboxy metabolite is primarily used in forensic and clinical toxicology as a biomarker for detecting valeryl fentanyl exposure. It helps identify and confirm the presence of valeryl fentanyl in biological samples, such as blood or urine, aiding in investigations related to drug abuse or overdose cases. Its detection is crucial for monitoring illicit fentanyl analog use and assessing public health risks associated with synthetic opioids. Additionally, it supports research on the metabolism and pharmacokinetics of fentanyl derivatives, contributing to the development of effective detection methods and harm reduction strategies.