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ABSTRACT: Intramedullary schwannomas unrelated with neurofibromatosis are uncommon tumors, but if correctly diagnosed and properly treated they may have a good prognosis.They have a wide range of clinical presentations, commonly presenting as a slowly progressive motor or sensory syndrome. We present a case report of a patient without neurofibromatosis with a surgically treated cervical intramedullary schwannoma.
Rare tumors 01/2009; 1(2):e44.
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ABSTRACT: A simple and sensitive procedure using solid-phase microextraction coupled with high performance liquid chromatography (HPLC) to analyze fluoxetine (FLU) and its metabolite norfluoxetine (nor-FLU) in plasma samples was developed and validated. SPME conditions were optimized employing a factorial design. The sampling step was performed using a PDMS-DVB fiber and desorption was carried out in a novel homemade heated interface. Fluoxetine and norfluoxetine were analyzed by HPLC, using a C18 Phase Sep column (150mmx4.6mm, 3microm) packed "in house", and acetonitrile:acetate buffer 25mmoll(-1) with triethylamine 25mmoll(-1) pH 4.6 (70:30) as the mobile phase. The developed method has shown precision, linearity, specificity, and limit of quantification (LOQ) adequate to assay fluoxetine and norfluoxetine in plasma. Furthermore, the results obtained using the homemade interface has shown an improvement in the desorption process when compared with the results obtained using the off-line mode.
Journal of Chromatography B 04/2007; 847(2):217-23. · 2.89 Impact Factor
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ABSTRACT: Solid-phase microextraction (SPME)-liquid chromatography (LC) is used to analyze tricyclic antidepressant drugs desipramine, imipramine, nortriptyline, amitriptyline, and clomipramine (internal standard) in plasma samples. Extraction conditions are optimized using a 2(3) factorial design plus a central point to evaluate the influence of the time, temperature, and matrix pH. A Polydimethylsiloxane-divinylbenzene (60-mum film thickness) fiber is selected after the assessment of different types of coating. The chromatographic separation is realized using a C(18) column (150 x 4.6 mm, 5-microm particles), ammonium acetate buffer (0.05 mol/L, pH 5.50)-acetonitrile (55:45 v/v) with 0.1% of triethylamine as mobile phase and UV-vis detection at 214 nm. Among the factorial design conditions evaluated, the best results are obtained at a pH 11.0, temperature of 30 degrees C, and extraction time of 45 min. The proposed method, using a lab-made SPME-LC interface, allowed the determination of tricyclic antidepressants in in plasma at therapeutic concentration levels.
Journal of chromatographic science 07/2006; 44(6):340-6. · 0.88 Impact Factor
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ABSTRACT: The aim of the study described in this report has been the development and the evaluation of a new improved interface to be operated under continuous heating, for on-line coupling solid-phase microextraction (SPME) to high-performance liquid chromatography (HPLC). Heating is desirable to increase desorption rate and decrease carryover. The results obtained have been compared with that obtained by off-line desorption and online desorption without heating. The SPME-HPLC interface described here has an inner volume of 60 microL, fixation for infinite points and a novel leak less sealing system. When the heating system was used, the area values were almost 10-fold higher than that obtained using the off-line mode. The obtained chromatograms showed an increasing of the area and height of chromatographic peaks and proved the excellent performance and reproducibility of the interface developed in this work.
Journal of Chromatography 03/2006; 1105(1-2):208-12. · 4.53 Impact Factor
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ABSTRACT: Fused silica packed capillary columns has been prepared using a new type of reservoir designed and engineered in house. We named it "cyclone" in analogy to an industrial equipment having similar shape. The performance of these columns was evaluated using solvating gas chromatography (SGC), a particular case of the transition phase chromatography (TPC); experiments showed that high efficient columns with a reduced plate height of ca. 2.0 were obtained even using 10 microns ODS particles. The advantageous features, obtained by using the cyclone device, make the newly developed columns suitable for separations of very complex samples and trace analysis. All steps involved in the preparation of the columns are addressed and discussed.
Journal of Chromatography 11/2005; 1090(1-2):172-7. · 4.53 Impact Factor
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ABSTRACT: The various forms of chromatography are primarily determined by differences in the physical state of the mobile phases. The main chromatographic categories include gas chromatography (GC), liquid chromatography, and supercritical fluid chromatography. Adjusting a temperature and pressure will change the mobile phase from liquid to supercritical fluid to gas, with concomitant changes in their physical properties. In this paper, the technique transition-phase chromatography (TPC) is described. In TPC, different mobile phase conditions exist inside the column. This phase transformation within the column results in huge differences in density, solvating power, viscosity, diffusivity, and, as a consequence, in the chromatographic properties of the mobile phase. TPC experiments using capillary columns packed in our laboratory have shown that when the mobile phase is transformed from supercritical fluid to gas, high column efficiencies can be achieved. The transition from supercritical fluid to gas (also called solvating GC), a particular case of the TPC, is evaluated for the separation of complex real samples (environmental, food, and fuels).
Journal of chromatographic science 08/2005; 43(6):277-81. · 0.88 Impact Factor
