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.

A fast, sensitive and simple method for mirtazapine quantification in human plasma by HPLC‐ESI‐MS/MS. Application to a comparative bioavailability study

“…However, the disadvantage of this method is the long analysis time (~15 min) and the LOQ of 1.25 ng/mL. Other LC‐MS/MS methods are even less sensitive, showing LOQs of over 10 ng/mL (de Santana et al ., ; Hong et al ., ; Kuchekar et al ., ; Wang et al ., ). The method described by Hong et al .…”

“…Despite the fact that LC-MS/MS is a very sensitive and selective technology, many of the reported methods described in the literature require laborious and timeconsuming extraction procedure like liquid-liquid extraction (LLE; Hong et al, 2008) and a long chromatographic run time. In addition, some of these methods require large volume of plasma, compromising their utilization in pharmacokinetics studies (de Santana et al, 2008a(de Santana et al, , 2010Kuchekar et al, 2011;Wang et al, 2009). The development of a sensitive and fast method applying only a small volume of biological fluid during sample preparation of antidepressants is not only of interest in the field of clinical toxicology, but also in forensics, as the drugs are often involved in intoxications (Adson et al, 2001;Anderson et al, 1999;Goeringer et al, 2000;Moore et al, 1999).…”

Enantiomeric separation of mirtazapine and its metabolite in rat plasma by reverse polar ionic liquid chromatography using fluorescence and polarimetric detectors connected in series

“…For this reasons a careful pretreatment using SPE with hydrophilic-lipophilic balance cartridge was proposed. Recently off-line solid-phase microextraction [10] and liquid-phase microextraction (LPME) [11] using porous polypropylene hollow fibre membrane were developed for simultaneous enantioselective determination of MTZ, DMTZ and 8-hydroxymirtazapine in plasma. However, all these procedures are not only tedious and time consuming but also involve additional steps of purification and concentration of biological samples.…”

Stereo‐specific LC and LC‐MS bioassays of antidepressants and psychotics

“…LC‐MS methods for enantioselective analysis of MRT, dimethyl MRT and 8‐hydroxy MRT in human plasma and urine were also reported. The chromatographic analyses were carried out on a Chiralpak AD‐RH column, using acetonitrile, methanol and ethanol containing 0.2% diethylamine as mobile phase (De Santana and Bonato, ; De Santana et al ., ). The extraction of MRT and its two major metabolites from human plasma were assessed by SPME and three‐phase liquid‐phasemicroextraction coupled to LC‐MS.…”

“…LC-MS methods for enantioselective analysis of MRT, dimethyl MRT and 8-hydroxy MRT in human plasma and urine were also reported. The chromatographic analyses were carried out on a Chiralpak AD-RH column, using acetonitrile, methanol and ethanol containing 0.2% diethylamine as mobile phase (De Santana and Bonato, 2008;De Santana et al, 2010). The extraction of MRT and its two major metabolites from human plasma were assessed by SPME and three-phase liquid-phasemicroextraction coupled to LC-MS. Enantiomers of MRT and two of its main metabolites, namely, 8-hydroxy MRT and N-desmethyl MRT extracted from human plasma using SPE were separated in to their enantiomers by nano-liquid chromatography with UV-absorption and mass spectrometric detection on a fused-silica capillary column packed with a vancomycin-modified silica stationary phase (Kingback et al, 2010).…”