Simultaneous Quantification of Methadone, Cocaine, Opiates, and Metabolites in Human Placenta by Liquid Chromatography-Mass Spectrometry

A validated method for quantifying methadone, 2-ethylidene-1,5-dimethyl-3,3-diphenylpyrrolidine, cocaine, benzoylecgonine, 6-acetylmorphine, morphine, and codeine in human placenta by liquid chromatography-ion trap mass spectrometry is described. Specimens (1 g) were homogenized and subjected to solid-phase extraction. Chromatographic separation was performed on a Synergi Polar RP column with a gradient of 0.1% formic acid and acetonitrile. The method was linear from 10 to 2000 ng/g for methadone and 2.5 to 500 ng/g for other analytes. Limits of detection were 0.25-2.5 ng/g, imprecisions < 9.1%CV, analytical recoveries 84.4-113.3%, extraction efficiencies > 46%, matrix effects -8.0-129.9%, and process efficiencies 24.2-201.0%. Method applicability was demonstrated by analysis of five placenta specimens from opioid-dependent women receiving methadone pharmacotherapy, with methadone doses ranging from 65 to 95 mg on the day of delivery. These are the first data on placenta concentrations of methadone and metabolites after controlled drug administration. Detection of other common drugs of abuse in placenta will also improve our knowledge of the usefulness of this matrix for detecting in utero drug exposure and studying disposition of drugs in the maternal-fetal dyad.