Application of microextraction by packed sorbent to isolation of psychotropic drugs from human serum.

A method of microextraction by packed sorbent (MEPS) followed by liquid chromatography with diode array detection has been developed and optimized for the extraction of six tricyclic antidepressants (amitriptyline, nortriptyline, imipramine, desipramine, doxepin, nordoxepin) from human serum. The optimal parameters of MEPS extraction (type of sorbent, volume of sample, composition, and volume of washing and elution solutions) for these drugs in spiked samples were defined. The developed MEPS procedure was validated and then successfully applied to the analysis of serum reference material. The limit of detection (0.02-0.05 µg/mL), intraday (2.7-8.8%) and interday (4.4-11.6%) precision (RSD), and the accuracy of the assay (94.5-108.8%) at three concentration levels-0.2, 0.5, and 0.8 µg/mL-were estimated. The accuracy of the method was evaluated by the analysis of certified reference material. Moreover, the validated procedure was compared with the solid-phase extraction technique. Finally, microextraction by packed sorbent was assessed as a suitable tool in forensic and clinical methods for serum sample preparations.

Microwave-assisted hydrolysis and extraction of tricyclic antidepressants from human hair.

The objective of this research was to develop, optimize, and validate a modern, rapid method of preparation of human hair samples, using microwave irradiation, for analysis of eight tricyclic antidepressants (TCADs): nordoxepin, nortriptyline, imipramine, amitriptyline, doxepin, desipramine, clomipramine, and norclomipramine. It was based on simultaneous alkaline hair microwave-assisted hydrolysis and microwave-assisted extraction (MAH-MAE). Extracts were analyzed by high-performance liquid chromatography with diode-array detection (HPLC-DAD). A mixture of n-hexane and isoamyl alcohol (99:1, v/v) was used as extraction solvent and the process was performed at 60°C. Application of 1.0 mol L(-1) NaOH and microwave irradiation for 40 min were found to be optimum for hair samples. Limits of detection ranged from 0.3 to 1.2 µg g(-1) and LOQ from 0.9 to 4.0 µg g(-1) for the different drugs. This enabled us to quantify them in hair samples within average therapeutic concentration ranges.

Identification of lipid derivatives in Hep G2 cells.

Metabolism of polyunsaturated fatty acids results in biosynthesis of mediators with different physiological effects. These metabolites include prostaglandins, prostacyclins, isoprostanes and others that are important signalling molecules and regulate a variety of physiological and pathophysiological processes including inflammation. Prostaglandins and isoprostanes are produced by either non-enzymatic lipid peroxidation or by enzyme-induced peroxidation (cyclooxygenases and lipoxygenases). They are used as biomarkers of oxidative stress. The aim of our study was to assess the effect of eicosapentaenoic acid (EPA) supplementation with added benzo(a)pyrene (BaP) on HepG2 cells by using a UHPLC/MS-TOF method. This rapid and simple method was developed for the identification, separation and quantification of 8-iPGF3α, PGF3α, 8-isoPGF2α and 5-iPF2α in cultured cells. The UHPLC/MS-TOF method was validated. The calculated limit of detection was in the range of 0.16-0.50 ng/mL, precision (% RSD): 1.2-2.1% and recoveries better than 88%. This method empowered qualitative and quantitative analysis of the selected individual prostaglandins derived from arachidonic acid and eicosapentaenoic acid from cell extracts.

Application of microwave irradiation to fast and efficient isolation of benzodiazepines from human hair.

The aim of this research was to develop, optimize and validate a modern and rapid method of preparation of human hair samples using microwave irradiation for the purpose of determination of six benzodiazepines: alprazolam, estazolam, lorazepam, clonazepam, diazepam and tetrazepam, with lormetazepam as an internal standard (IS). Extracts were analyzed ultrahigh performance liquid chromatography with mass spectrometry time of flight detection (UHPLC-MS-TOF). Optimal parameters of microwave-assisted extraction (type of extraction solvent, extraction temperature, extraction time and pH of borate buffer) for these drugs in spiked hair samples were defined. The limit of detection ((0.003-0.025 ng/mg), intra- (1.5-4.3%) and interday (2.3-8.3%) precision (CV) and accuracy of the assay (89.8-105.7%) at three concentration levels: 0.22, 2.22 and 5.56 ng/mg were calculated. The optimized and validated MAE/UHPLC-MS-TOF method was then applied for analysis of clinical hair sample.