An internal standard suitable for GC/MS or LC/MS applications with chlordiazepoxide or demoxepam such as toxicology analysis, forensic testing, pain prescription monitoring, or isotope dilution methods. Demoxepam is a benzodiazepine drug and anticonvulsant as well as a primary metabolite of chlordiazepoxide, marketed as Klopoxid or Librax for the treatment of anxiety and muscle spasms or pain.