Direct Injection Mass Spectrometric Confirmation of Multiple Drugs in Overdose Cases from Postmortem Blood Using Electrospray Ionization-Tandem Mass Spectrometry and MS3

Abstract

Five cases of confirmed multiple-drug overdose were previously screened and quantified by the West Virginia Office of the Chief Medical Examiner; 26 different drugs and metabolites were identified and quantified in blood at > or = 10 ng/mL. In this study, whole blood from those five case samples was analyzed by a direct injection multi-stage mass spectrometric (MSn) method to confirm the identity of 26 analytes at or above 10 ng/mL using 16 different deuterium-labeled internal standards. Samples were spiked with internal standards, precipitated with acetonitrile, and centrifuged. Samples were further diluted with either 0.1% formic acid or 0.1% ammonium hydroxide in methanol prior to injection into an electrospray ionization ion trap mass spectrometer (MS). Ions were monitored as MS-MS or MS3 product ions. In all cases, analysis by MS-MS confirmed the presence of the drugs and metabolites when the internal standards were detected. Detection of characteristic MS3 ions was used for further confirmation of the presence of parent drugs in all but three instances. Total analysis time was less than 1 h. Although only useful for qualitative or confirmatory purposes, this direct injection MSn method provides a simple and rapid confirmation of multiple drugs that have been previously identified and quantified by gas chromatographic-MS or liquid chromatographic-MS analytical methods.