Simultaneous quantitation of morphine, 6-acetylmorphine, codeine, 6-acetylcodeine and tramadol in hair using mixed-mode solid-phase extraction and gas chromatography-mass spectrometry

1. Barroso, M.
2. Dias, M.
3. Vieira, D.N.
4. López-Rivadulla, M.
5. Queiroz, J.A.