title: Enantioselective analysis of mirtazapine, demethylmirtazapine and 8-hydroxy mirtazapine in human urine after solid-phase microextraction.
abstract: A selective and reproducible off-line solid-phase microextraction procedure was developed for the simultaneous enantioselective determination of mirtazapine (MRT), demethylmirtazapine and 8-hydroxymirtazapine in human urine. CE was used for optimization of the extraction procedure whereas LC-MS was used for method validation and application. The influence of important factors in the solid-phase microextraction efficiency is discussed, such as the fiber coatings, extraction time, pH, ionic strength, temperature and desorption time. Before extraction, human urine samples were submitted to enzymatic hydrolysis at 37 degrees C for 16 h. Then, the enzyme was precipitated with trichloroacetic acid and the pH was adjusted to 8 with 1 mol/L pH 11 phosphate buffer solution. In the extraction, the analytes were transferred from the aqueous solution to the polydimethylsiloxane-divinylbenzene fiber coating and then desorbed in methanol. The mean recoveries were 5.4, 1.7 and 1.0% for MRT, demethylmirtazapine and 8-hydroxymirtazapine enantiomers, respectively. The method was linear over the concentration range of 62-1250 ng/mL. The within-day and between-day assay precision and accuracy were lower than 15%. The method was successfully employed in a preliminary cumulative urinary excretion study after administration of racemic MRT to a healthy volunteer.
authors.affiliation: Departamento de Fisiologia, Curso de Farmácia, Universidade Federal de Sergipe, São Cristóvão, Sergipe, Brazil. malagueno@ufs.br
authors.forename: Fernando José Malagueño
authors.initials: FJ
authors.lastname: de Santana
authors.forename: Valquíria Aparecida Polisel
authors.initials: VA
authors.lastname: Jabor
authors.forename: Evandro José
authors.initials: EJ
authors.lastname: Cesarino
authors.forename: Vera Lúcia
authors.initials: VL
authors.lastname: Lanchote
authors.forename: Pierina Sueli
authors.initials: PS
authors.lastname: Bonato
mesh_terms: D000929:Antidepressive Agents, Tricyclic / Q000008:administration & dosage / Q000032:analysis / Q000493:pharmacokinetics / Q000652:urine; D002021:Buffers; D002853:Chromatography, Liquid; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008803:Mianserin / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000302:isolation & purification / Q000493:pharmacokinetics / Q000652:urine; D000078785:Mirtazapine; D009994:Osmolar Concentration; D015203:Reproducibility of Results; D052617:Solid Phase Microextraction / Q000295:instrumentation / Q000379:methods*; D013237:Stereoisomerism; D053719:Tandem Mass Spectrometry
chemical_list: D000929:Antidepressive Agents, Tricyclic; D002021:Buffers; D008803:Mianserin; D000078785:Mirtazapine; C415843:8-hydroxymirtazapine; C119256:demethylmirtazapine