Analysis of Citalopram in Plasma and Hair by a Validated LC MS/MS Method

Abstract

A simple method for quantification of citalopram in mice plasma and hair was developed and validated using liquid chromatography tandem mass spectrometry (LC–MS/MS). The procedure involves a protein precipitation extraction of citalopram and desipramine (internal standard) with methanol from mice plasma. On the other hand, hair samples were incubated overnight with methanol at 45°C followed by μ-SPE (OMIX Tip). The analysis was performed by resolving analytes in a Gemini® C18 column with a gradient of 0.1% formic acid in water and 0.1% formic acid in acetonitrile, at a flow rate of 250 μL/min and with a total run time of 9 min. The mass spectrometer was operated in multiple reaction monitoring (MRM) by monitoring citalopram transition 325.3→109.0, and internal standard transition 267.3→72.2 for quantification. The qualifier transitions 325.3→83.1 and 267.3→190.8, respectively, were also monitored. Linearity was observed from 32.4 to 973.2 ng/mL and the limit of quantitation achieved was 32.4 ng/mL. Also, the intermediate precision, repeatability and accuracy were below the acceptance limits of 15%. This method was applied to plasma and hair samples that were collected from mice submitted to a treatment with citalopram for different days. The plasma concentration–time profile of citalopram showed a tendency to stabilize, approaching zero as samples were collected 24 hours after the last drug administration. In contrast, the concentration-time profile in hair increased over the period of 30 days.