Analysis of Barbiturate Mixtures Using HPLC with Diode Array Detection

Abstract

A study has been conducted on the HPLC analysis of barbiturate mixtures in which coeluting components with similar UV spectra could be distinguished by diode array detection. Mixtures containing phenobarbital and barbital in combination from about 0.25 to 0.00025 mg/mL each were measured using the spectral overlay, absorbance ratio, peak maximum absorbance and purity parameter techniques. The most sensitive of the standard methods available was absorbance ratio plotting in which the presence of 0.0125 mg/mL barbital could be distinguished from phenobarbital at 0.2375 mg/mL.