Abstract: Objective: To establish a high performance liquid chromatography tandem mass spectrometry (HPLC / MS) method for the simultaneous determination of three antidepressant drugs in feces. Methods: Samples were pretreated with n-hexane isopropanol (95:5, v/v). Gradient elution was carried out with mixed liquid of ultrapure water and acetonitrile as mobile phase and separated by Agilent ZORBAX SB-C18 liquid chromatography column (2.1 mm×100 mm, 3.5 m). The samples were detected by electrospray ionization tandem mass spectrometry and quantified by internal standard method. Results: The recoveries of duloxetine, fluoxetine and escitalopram in fecal samples were 61.6% - 116.5%, with precision of 2.80% - 12.9% (n=5). The correlation coefficients (r) of linear equations were all greater than 0.995. The detection limits were 0.1, 1, and 0.001 μg/g, and the limits of quantification were 0.5, 2 and 0.005 μg/g, respectively. Conclusion: The method is simple and accurate to detect the contents of three antidepressants in feces, such as duloxetine, fluoxetine and escitalopram.

Key words: feces, HPLC-MS, antidepressants, mice