Improved detectability of barbiturates in high-performance liquid chromatography by pre-column labelling and ultraviolet detection

Abstract

2-Naphthacyl derivatives of barbiturates are formed in acetone at 30° within 30 min, in an essentially quantitative manner, using caesium carbonate as a catalyst. These derivatives absorb UV radiation strongly at 254 nm. Using a variable-wavelength detector set at 249 nm, 1 ng of N,N-dinaphthacylphenobarbital could be detected after chromatography using a high-performance liquid chromatograph equipped with a microparticulate reversed-phase column. This derivatization technique has the potential of allowing the determination of barbiturates, in small plasma or serum samples, in concentrations well below the therapeutic range.