THE DETERMINATION OF METHADONE AND METABOLITES IN HUMAN URINE BY HPLCWITH ULTRAVIOLET, AND PARTICLE-BEAM MASS-SPECTROMETRIC DETECTION

Liquid chromatography coupled to Mass Spectrometry has been used to id entify and quantitate methadone and two of its metabolites following a normal phase separation on a cyano-phase column. Solvent extraction w as used to recover the target compounds from urine at the optimal pH o f 10, (recovery: 88%, methadone; 75%, 2-ethylidene-1,5-dimethyl-3,3-di phenylpyrrolidine (EDDP). Routine analysis may be performed using UV d etection at 290 nm. However, for greater selectivity and identificatio n of eluates mass spectrometry is preferred. In the urine samples stud ied the methadone/EDDP ratio varied from 1:1 to 1:10. Two samples show ed evidence for the presence of 1,5-dimethyl-3,3-diphenplpyrrolidone ( DDP). Methadone may be detected selectively at m/z = 223 but the ion a bundance is weak. Detection using the base peak m/z = 72 is preferred because of the increased sensitivity it confers although selectivity o f detection is lost.