An Enantiomer-Selective Liquid Chromatography—Tandem Mass Spectrometry Method for Methadone and EDDP Validated for Use in Human Plasma, Urine, and Liver Microsomes.

The article discusses the development and validation of a liquid chromatography-electrospray ionization-tandem mass spectrometry method to detect (R)- and (S)-methadone and (R)- and (S)-2ethylidene-1,5-dimethyl-3,3-diphenylpyrrolidine (EDDP) in human plasma with cross substantiation to urine and liver microsomes. It is suggested that the use of deuterated internal standards and liquid-liquid extraction matched with chiral separation allowed for baseline separation with a lower limit of quantitation (LLOQ) of 2.5ng/ml.