Identification of an unknown trace-level impurity in bulk drug of Seroquel by high-performance liquid chromatography combined with mass spectrometry

An impurity was detected in bulk drug Seroquel at about 0.4% level by the reversed-phase high-performance liquid chromatography with UV detection. The accurate mass of impurity was measured by FTICR equipped with electrospray ionization interface, and the structure of impurity was characterized on the basis of the on-line multi-stage mass spectrometric evidences. The proposed structure was further confirmed by multi-stage mass spectrometry of Seroquel and four related compounds.