Chromatographic tandam mass spectrometric detection of papaverine and its major metabolites in rat urine

A rapid, sensitive and specific liquid chromatographic-electrospray ionization (ESI) tandem ion trap mass spectrometric method has been developed for identification of papaverine and its metabolites in rat urine. Six healthy rats were administrated a single dose (100 mg/kg) of papaverine by oral gavage. The urine were sampled for 0–24 h and purified by using a C18 solid-phase extraction cartridge, then the purified urine samples were separated on a reversed-phase C18 column using methanol/2 mmol/L ammonium acetate (70:30, v/v, adjusted to pH 3.5 with formic acid) as mobile phase and detected by an on-line MS detector. Identification and structural elucidation of the metabolites were performed by comparing their changes in molecular mass (Δm) and full scan MSn spectra with those of the parent drug. The results indicated that there were 14 metabolites in rat urine, such as de-methoxyl, hydroxyl, glucuronide and sulfate conjugated metabolites and so on. All these metabolites were reported for the first time.