Chinese Journal of Chromatography
Simultaneous determination of four opioids in urine by solid-phase extraction and derivatization coupled with gas chromatography-mass spectrometry
Hang GAO, Yaxun LIU, Wei KE, Kai LIU, Liuyang NI, Tao TAO
Chinese Journal of Chromatography . 2020, (11): 1348 -1354 .  DOI: 10.3724/SP.J.1123.2020.06002