An on-line solid phase extraction—Liquid chromatography—Tandem mass spectrometry method for the analysis of citalopram, fluvoxamine, and paroxetine in human plasma

A specific and sensitive direct-injection high performance liquid chromatography atmospheric pressure chemical ionization tandem mass spectrometry (HPLC-APCI-MS-MS) method has been developed for the rapid identification and quantitative determination of citalopram, fluvoxamine, and paroxetine in human plasma. After dilution with 0.1% formic acid, plasma samples were injected into the LC-MS-MS system. Proteins and other large biomolecules were removed during an on-line sample cleanup step. The inter- and intra-assay coefficients of variation for all compounds were <11%. The total analysis time was 6 min per sample. The proposed method permits direct analysis of plasma samples without time-consuming sample preparation.