1,721,057 research outputs found
Recent trends in the analysis of amino acids in fruits and derived foodstuffs
No full textThe amino acid content of fruit and fruit-derived foods is intensely studied, because of their contribution to nutritional value, aroma, taste and health-promoting effects and their possible use as markers of origin and authenticity. In this review, based on 101 references, the most recent trends in the analysis of amino acids are presented: the most important techniques, the different sample treatment procedures (including derivatisation) and the most frequent applications are described and compared.
Pertinent publications were retrieved from Scopus and Web of Knowledge database searches lastly performed in February 2012 with the keywords "amino acid", "analysis", "liquid chromatography", "gas chromatography", "electrophoresis", "fruit", "vegetables"; the time limit was set from the year 2000 onwards.
Although amino acids have been analysed in foods for decades, new technical possibilities and advancements have allowed ever increasing accuracy and targeting of the methods, in order to overcome the challenges posed by the complex plant matrices and by their high intrinsic variability
Monitoring of amino acids in plasma by LC with fluorescence detection
No full textAmino acids are a very interesting class of biologically active compounds, being the principal component of proteins and precursors of important neurotransmitters and neuromodulators, such as catecholamines (phenylalanine and tyrosine), histamine (histidine), nitric oxide (arginine), and serotonin (tryptophan). Plasma amino acid concentration may be a regulating factor of neurotransmitter biosynthesis in the brain. As cognitive disorders increase exponentially with age, few data are available about plasma amino acid concentrations in elderly persons in relation to their cognitive status. Various dietary supplements containing amino acids are proposed to influence ageing, memory loss and cognitive function, despite sparse scientific data for the efficiency of these supplements.
Plasma analysis is hampered by the presence of a variety of amino acids at considerable different concentrations and their direct determination is difficult for the lack of significant chromophore and fluorophore groups. The reversed-phase liquid chromatography (RP-LC) combined with pre-column derivatization is a reliable way to overcome the problem.
The purpose of the present work was to optimize and apply an HPLC method, which involves o-phthaldialdehyde (OPA) as fluorogenic derivatization reagent, to the selective and sensitive determination of amino acids in plasma of elders before and after oral treatment with poly amino acid formulations. Blood samples were subjected to centrifugation and the obtained plasma was deproteinized with 5-sulfosalicylic acid. The derivatization reaction was carried out at room temperature for 1 min in presence of borate buffer (pH 9.5; 0.4 M). The RP-HPLC separations with fluorescence detection were performed on a Phenomenex Gemini 5mm C18 (250 x 3 mm i.d.) column using two different mobile phases under gradient elution conditions. The combination of both chromatographic methods, employing mobile phases at different pH, provided a system with orthogonal selectivity, which allows a sure identification of a variety of amino acids in a complex matrix as plasma.
Studies are in progress to extend the application to a large number of samples in order to evaluate both the correlation of plasma amino acid profile with the cognitive status and the effect of dietary supplement administration
Dried blood spot testing: a novel approach for the therapeutic drug monitoring of ziprasidone-treated patients
No full textBackground: A novel analytical approach, based on dried blood spot (DBS) testing, has been developed, validated and applied for the first time to the analysis of ziprasidone (ZPR) for the therapeutic drug monitoring (TDM) of schizophrenic patients. DBS represent a more feasible but reliable matrix, alternative to blood and plasma. Methods: The assays were carried out using an HPLC method with native fluorescence. Blood drops were applied to DBS cards and dried by microwaves, an internal standard solution was added to the DBS and 5-mm punches were cut out for analysis. ZPR was extracted from DBS with methanol, giving good extraction yields, precision and selectivity results. Results: The method was applied with satisfactory results to DBS samples from psychiatric patients to determine ZPR levels for therapy optimization. Conclusion: This innovative methodology provides reliable and significant TDM information, with important advantages over classical blood sampling in terms of collection, storage and processing
Multi-matrix assay of the first melatonergic antidepressant agomelatine by combined liquid chromatography-fluorimetric detection and microextraction by packed sorbent
No full textA rapid and reliable analytical method has been developed to quantify the melatonergic antidepressant agomelatine in three matrices, and namely saliva, plasma and dried blood spots. The method is based on the use of liquid chromatography with fluorimetric detection exploiting the native fluorescence of agomelatine. For saliva and plasma samples an original microextraction by packed sorbent procedure was implemented obtaining satisfactory extraction yield of the analyte (always higher than 89%) and a good clean-up of the matrices. On the contrary, agomelatine was extracted from dried blood spots by suitable solvent microwave-assisted extraction and injected into chromatographic system. Satisfactory results in terms of sensitivity, linearity, precision, selectivity and accuracy were obtained. Thus, the developed method seems to be suitable for therapeutic drug monitoring of depressed patients under agomelatine therapy
Simultaneous high-performance liquid chromatographic determination of olanzapine and lamotrigine in plasma of bipolar patients
Full text linkAn original method based on the use of high-performance liquid chromatography with both coulometric and diode array detection has been developed for the therapeutic drug monitoring of patients with bipolar disorders being treated with olanzapine and lamotrigine. Chromatographic separation was achieved on a reversed-phase C8 column (150 X 4.6 mm internal diameter, 5 mu m) using a mobile.phase composed of methanol (27%) and a 50.0 mmol/L, pH 3.5 phosphate buffer (73%). For the analysis of olanzapine and its main metabolite, N-desmethylolanzapine, a coulometric detector was used, with electrode 1 set at -200 mV and electrode 2 at +500 mV Lamotrigine was determined using a diode array detection at 220 nm. The two detectors were connected in series. For the analysis of biological samples, a clean-up procedure was implemented by means of solid-phase extraction using phenyl cartridges and eluting the analytes with methanol; only a small volume of plasma (150 mu L) was needed to analyze both olartzapine and lamotrigine. Linear responses were obtained between 0.1 and 50.0 ng mL(-1) for olanzapine, 0.1 and 25.0 ng mL(-1) for N-desmethylolanzapine, and between 0.25 and 10.0 mu g mL(-1) for lamotrigine. The extraction yield values were always higher than 90% for all the analytes, with precision (expressed as relative standard deviation values) lower than 3.4%. The method was applied successfully to some human plasma samples drawn from bipolar patients undergoing combined therapy with the two drugs. Satisfactory values for accuracy were obtained, with mean recovery higher than 91%. Thus, the method appears suitable for the investigation of the chemical-clinical correlations in patients receiving therapy with olanzapine and lamotrigine
Quantitative Evaluation of Auraptene and Umbelliferone, Chemopreventive Coumarins in Citrus Fruits, by HPLC-UV-FL-MS
No full textAn analytical strategy, based on the development of two HPLC methods with spectrophotometric (UV), spectrofluorometric (FL), and mass spectrometric (MS) detection, has been developed to investigate the presence of and to quantitate two important chemopreventive coumarins, auraptene and umbelliferone, in foodstuffs. The analytes were determined in fruits, and fruit parts, of plants belonging to the Citrus, Poncirus, and Fortunella genera, to test their nutraceutical potential. The method validation has been carried out according to international guidelines, with good results in terms of precision (RSD 91%). Application to the quantitative analysis of auraptene and umbelliferone in several kinds of citrus fruits was successful, providing reliable and consistent data. Exploiting three different kinds of detection, the analytical methodology proposed herein has been demonstrated to be sound but versatile, as well as reliable. Performances and results were compared and always found in good agreement among themselves. Thus, this approach is suitable for the identification and simultaneous quantitation of auraptene and umbelliferone in citrus fruits, with the aim of evaluating their nutraceutical potential
Recent Patents on Nanotechnology
No full textRivista internazionale con Impact Factor attiva nel campo delle nanotecnologie mediche, ed in particolare nel settore della proprietà intellettuale
Journal of Pharmaceutical and Biomedical Analysis
No full textUna delle più prestigiose riviste internazionali con Impact Factor nel campo delle metodiche analitiche farmaceutiche e biomediche
International Journal of Analytical Chemistry
No full textRivista internazionale in lingua inglese che pubblica nel campo delle scienze chimico-analitiche
Procedimento per la conservazione di un campione di fluido biologico e sua analisi
No full textMetodo per la conservazione e l’analisi di un fluido biologico contenente un composto oppiaceo/oppioide; il metodo prevede di essiccare una goccia del fluido su un supporto di carta mediante microonde in modo da ottenere una macchia secca (dried spot), conservare la macchia secca ed estrarre il composto oppiaceo/oppioide dal supporto di carta e sottoporlo a cromatografia liquida ad alta pressione con rivelazione spettrofluorimetrica o a cromatografia liquida accoppiata a spettrometria di massa ed una loro combinazione
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