Analysis of atropine and its metabolites in rat feces by electrospray ionization randem mass spectrometry

A method is described for the identification of atropine and its metabolites in rat feces by combining liquid chromatography and tandem mass spectrometry (LC-MSn). The feces samples were collected after single administration of 25 mg/kg atropine to rats, and soaked in water for 1 h. Then, atropine and its metabolites were extracted by ethyl acetate. The extracted samples were separated on a reversed phase C-18 column using a mobile phase of methanol/ammonium acetate (2 mmol/L, adjusted to pH 3. 5 with formic acid (70:30, V/V) and detected by LC/MSn. By comparing retention-times, full scan MS and MS' spectra among extracts, parent drug and blank feces, metabolite structures were deduced: nortropine, tropine, tropic acid, aponoratropine, apoatropine, noratropine, hydroxyatropine, hydroxyatropine N-oxide and hydroxy-methoxyatropine. This method is rapid, convenient, and suitable for the rapid identification of drug metabolites in biologic samples.