Flow-injection spectrophotometric determination of enalapril in pharmaceuticals with bromothymol blue

Enalapril (1.5–60 μ gl^?1) in aqueous solution is extracted into dichloromethane as its ion-pair with bromothymol blue in an unsegmented flow system and quantified spectrophotometrically. Up to 80 samples h^?1 can be processed, with r.s.d. of 1.0–3.4%. The degradation products of enalapril and excipients in the pharmaceutical dosage form do not interfere.