Drug quality assessment methods. I. Gas-liquid chromatographic assay and identification of seven barbiturates.

A gas-liquid chromatographic (GLC) procedure has been developed for the assay and identification of amobarbital, butabarbital, heptabarbital, mephobarbital, pentobarbital, phenobarbital, and secobarbital in single component capsule, elixir, injectable, suppository, and tablet formulations. After extraction into chloroform from an acidified aqueous mixture of the product, the drug is eluted isothermally from a methylphenylsilicone GLC column at 210 or 240 degrees C and quantitated relative to thiamylal internal standard. Results were in good agreement with those obtained using pharmacopeial assay methods. The method is suitable for the rapid assessment of commercial formulations.