1,721,003 research outputs found
Efficacy of quietiapine in the treatment of behavioral symptoms in dementia
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Supercritical fluid extraction combined on-line with cold-trap gas chromatography/mass spectrometry
No full textOn-line coupling of a supercritical fluid extraction (SFE) system with a gas chromatography/mass spectrometry (GC/MS) instrumentation was performed by a home-made suitably shaped accumulation cell. This coupling eliminates the effect of CO2 how on the MS detector, and considerably reduces the effect of high boiling compounds on the chromatographic efficiency in the determination of organic pollutants in environmental samples. Moreover, it enables multi-step extraction based on the addition of the CO2 modifier directly into the extraction cell. In particular, a three-step extraction of some selected polycyclic hydrocarbons (PAHs) from harbour certified marine sediment reference material was performed at 70 degrees C extraction temperature, 20 MPa extraction pressure, 400 mu l min(-1) supercritical CO2 flow for a total extraction time of 15 min (i.e. 5 min for each extraction step), and showed recoveries between 80% and 100% for all PAHs considered with a coefficient of variation of about 10%
Development and validation of a novel derivatization method for the determination of lactate in urine and saliva by liquid chromatography with UV and fluorescence detection
No full textWe developed a novel and straightforward derivatization method for the determination of lactate by reversed phase high-performance liquid chromatography (RP-HPLC) with fluorescence and UV detection in biological matrices as urine and saliva. The derivatization of lactate was achieved employing 9-chloromethyl anthracene (9-CMA) as fluorescence reagent, which has never been previously used to obtain a lactate derivative. Lactate reacts with 9-CMA with high selectivity in a very short time, without requiring extraction procedures from the aqueous solution, and the reaction reaches 70% completion in 30 min. The ester derivative obtained can be easily determined by RP-HPLC with fluorescence detection at 410 nm (lambda ex=365 nm) and UV detection at 365 nm. The method was also optimized in order to allow for the simultaneous determination of lactate and creatinine for the application to urine samples. The lactate calibration curve was linear in the investigated range 2 * 10(-4)-3 * 10(-2)mM and the limit of detection, calculated as three times the standard deviation of the blank divided by the calibration curve slope, was 50 nM for both fluorescence and UV detection. Intra-day and inter-day repeatability were lower than 5% and 6%, respectively. The method proposed was successfully applied to the analysis of urine and saliva samples
Olanzapina vs Haloperidol:plasma levels and clinical efficacy on cognitive function in 37 schizophrenic patients
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HS-SPME-GC-MS approach for the analysis of volatile salivary metabolites and application in a case study for the indirect assessment of gut microbiota
Full text linkIn this work, a straightforward analytical approach based on headspace solid-phase microextraction coupled with gas chromatography-mass spectrometry was developed for the analysis of salivary volatile organic compounds without any prior derivatization step. With a sample volume of 500 μL, optimal conditions were achieved by allowing the sample to equilibrate for 10 min at 50 °C and then extracting the samples for 10 min at the same temperature, using a carboxen/polydimethylsiloxane fibre. The method allowed the simultaneous identification and quantification of 20 compounds in sample headspace, including short-chain fatty acids and their derivatives which are commonly analysed after analyte derivatization. The proof of applicability of the methodology was performed with a case study regarding the analysis of the dynamics of volatile metabolites in saliva of a single subject undergoing 5-day treatment with rifaximin antibiotic. Non-stimulated saliva samples were collected over 3 weeks from a nominally healthy volunteer before, during, and after antibiotic treatment. The variations of some metabolites, known to be produced by the microbiota and by bacteria that are susceptible to antibiotics, suggest that the study of the dynamics of salivary metabolites can be an excellent indirect method for analysing the gut microbiota. This approach is novel from an analytical standpoint, and it encourages further studies combining saliva metabolite profiles and gut microbiota dynamics. [Figure not available: see fulltext.]
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