Identification and quantification of 4′-methoxy-α-pyrrolidinobutiophenone (4-MeOPBP) in human plasma and urine using LC–TOF-MS in an autopsy case

We encountered an autopsy case of a 35-year-old man who drowned in a bathtub. Nine opened packages of designer drugs containing herbal blends, powders, or liquid were found at the scene, implying abuse. The plasma and urine samples of the deceased were analyzed using liquid chromatography–time-of-flight-mass spectrometry (LC–TOF-MS) with MS^E. A new synthetic cathinone, 4′-methoxy-α-pyrrolidinobutiophenone (4-MeOPBP), emerged as a suspected component via elemental composition and molecular structure analyses with acquisition of full spectra of the precursor and product ions by MS^E mode. The component was finally identified by comparing the mass spectra obtained from the deceased’s samples with those of the reference standard 4-MeOPBP using LC–TOF-MS and gas chromatography–mass spectrometry. Furthermore, 4-MeOPBP was the main component of an opened package labeled “Silver Snow”. The concentrations of 4-MeOPBP in plasma and urine samples were as high as 9.5 and 12 μg/ml, respectively. To our knowledge, this is the first report disclosing 4-MeOPBP in human specimens.