An internal standard suitable for LC/MS or GC/MS applications with oxazepam and oxazepam glucuronide such as toxicology analysis, forensic testing, pain prescription monitoring, or isotope dilution methods. Oxazepam, marketed as Alepam, Medopam, or Murelax, is a benzodiazepine used extensively since the 1960s for treatment of anxiety and insomnia and in the control of symptoms of alcohol withdrawal.