Determination of methotrimeprazine in pharmaceutical preparations by visible spectrophotometry

A spectrophotometric method is described for determination of methotrimeprazine (levomepromazine). The aim of this work was to develop a simple, rapid, precise, and accurate visible spectrophotometric method for determination of methotrimeprazine in tablet, oral solution, and injection. The method is based on methotrimeprazine reaction with bromophenol blue, resulting in a stable, light yellow-green ion-pair complex that, after extraction with chloroform, presented maximum absorption at 409 nm. Beer's law was obeyed in the concentration range from 5.0 to 25.0 μg/ml. The proposed standardized method was applied to commercially available and simulated samples. The accuracy of the method was confirmed by recovery tests.