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1.
Int J Infect Dis ; 108: 300-305, 2021 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-33930543

RESUMEN

BACKGROUND: The impact of COVID-19 on the diagnosis and management of tuberculosis (TB) patients is unknown. METHODS: Participating centres completed a structured web-based survey regarding changes to TB patient management during the COVID-19 pandemic. The study also included data from participating centres on patients aged ≥18 diagnosed with TB in 2 periods: March 15 to June 30, 2020 and March 15 to June 30, 2019. Clinical variables and information about patient household contacts were retrospectively collected. RESULTS: A total of 7 (70%) TB units reported changes in their usual TB team operations. Across both periods of study, 169 patients were diagnosed with active TB (90 in 2019, 79 in 2020). Patients diagnosed in 2020 showed more frequent bilateral lesions in chest X-ray than patients diagnosed in 2019 (P = 0.004). There was a higher percentage of latent TB infection and active TB among children in households of patients diagnosed in 2020, compared with 2019 (P = 0.001). CONCLUSIONS: The COVID-19 pandemic has caused substantial changes in TB care. TB patients diagnosed during the COVID-19 pandemic showed more extended pulmonary forms. The increase in latent TB infection and active TB in children of patient households could reflect increased household transmission due to anti-COVID-19 measures.


Asunto(s)
COVID-19 , Tuberculosis , Niño , Trazado de Contacto , Humanos , Pandemias , Estudios Retrospectivos , SARS-CoV-2 , España/epidemiología , Tuberculosis/diagnóstico , Tuberculosis/tratamiento farmacológico , Tuberculosis/epidemiología
2.
Eur J Clin Microbiol Infect Dis ; 39(6): 1089-1094, 2020 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-31980987

RESUMEN

The epidemiology of non-tuberculous mycobacteria (NTM) in Spain is largely unknown because systematic reporting is not compulsory. The aim of our study was to describe the frequency and diversity of NTM species in our region and their distribution according to the source sample, gender, and age of the patients. We performed a multicenter study of all NTM isolated in 24 public hospitals in Madrid from 2013 to 2017. A total of 6.923 mycobacteria were isolated: 4535 (65.5%) NTM, and 2.388 (34.5%) Mycobacterium tuberculosis complex (MTB). Overall, 61 different NTM species were identified. The most frequently isolated species were Mycobacterium avium complex (47.7%), M. lentiflavum (12.2%), M. gordonae (9.2%), M. fortuitum (8.9%), and M. abscessus (3.9%). Whereas MTB cases were stable during the study period, the number of NTM isolates increased considerably from 930 isolates in 2013 to 1012 in 2017; a sharp increase occurred in the last year. The rise in NTM isolates was mostly due to M. lentiflavum, M. kansasii, and M. abscessus mainly isolated from respiratory specimens in patients older than 60. The increase in isolation rate of NTM in our region is consistent with the increasing rates reported worldwide in the last decades. The rise in NTM isolates was mainly attributed to M. lentiflavum but it also should be noted the increasing of species with high pathogenic potential such as M. kansasii and M. abscessus.


Asunto(s)
Infecciones por Mycobacterium no Tuberculosas/epidemiología , Infecciones por Mycobacterium no Tuberculosas/microbiología , Micobacterias no Tuberculosas/aislamiento & purificación , Femenino , Humanos , Laboratorios de Hospital , Masculino , Persona de Mediana Edad , Micobacterias no Tuberculosas/clasificación , Estudios Retrospectivos , España/epidemiología , Tuberculosis/epidemiología , Tuberculosis/microbiología
3.
Talanta ; 195: 796-799, 2019 Apr 01.
Artículo en Inglés | MEDLINE | ID: mdl-30625619

RESUMEN

A device for headspace sorptive extraction (HSSE) combined with gas chromatography separation and mass spectrometry detection (GC-MS) is presented. The gadget is based on a simple magnetic disk that permits the stir bar to be placed at the top of the sample vial. The complete surface of the coated stir bar is exposed to the headspace atmosphere, and the movement of the bar caused by the magnetic stirrer in the liquid sample facilitates the sorption process. The final consequence is increased sensitivity and repeatability when compared with a glass-made comercial device for the same purpose. Successful determination of ten chlorobenzenes in waters testifies the good performance of the new device.

4.
Radiologia (Engl Ed) ; 60(4): 326-331, 2018.
Artículo en Inglés, Español | MEDLINE | ID: mdl-29779857

RESUMEN

OBJECTIVE: To analyze the incidence of contrast-induced nephropathy in a cohort of patients undergoing computed tomography (CT) with intravenous iodinated contrast material. To evaluate the efficacy of N-acetylcysteine in preventing contrast-induced nephropathy. PATIENTS AND METHODS: This prospective observational study was carried out in the months comprising March 2016 through July 2016. We selected the first five patients scheduled to undergo CT examination each day who agreed to participate and signed the informed consent form. We recorded patients' cardiovascular histories, chronic treatments, and indications for the CT examination. We measured blood levels of creatinine and urea before and after the CT examination. We used the Modification of Diet in Renal Disease (MDRD-4) equation to estimate the glomerular filtration rate. We analyzed the type and dose of contrast material. We recorded whether N-acetylcysteine was administered before the CT examination. We used SPSS 15.0® to compare means and proportions. Statistical significance was set at p < 0.05. RESULTS: No incidents of contrast-induced nephropathy were detected in any of the 202 patients included [mean age, 63.92 ± 12 years (range 22-87); 57.4% male; 21.8% diabetic; 39.6% hypertensive; 87.1% had MDRD4 ≥ 60 ml/min/1.73 m2 (89.45 ± 14, range 62.36-134.14) and 12.9% had MDRD4 < 60 ml/min/1.73 m2 (45.38 ± 11, range 9.16-58.90)]. The most common indication for CT examinations was oncologic (81.2%). The only contrast agent administered was iopamidol; the mean dose was 107.83 ± 11 ml (range 70-140). The mean interval between pre-CT and post-CT laboratory tests was 4.06 ± 1 days. Only 13 patients received N-acetylcysteine; 9 of these had MDRD < 60 ml/min/1.73 m2 and 4 had MDRD4 ≥ 60 ml/min/1.73 m2 (p = 0.000). CONCLUSIONS: The incidence of contrast-induced nephropathy was not significant in patients with glomerular filtration rates greater than 30 ml/min/1.73 m2: these favorable results might be due to analyzing only scheduled examinations and to using relatively low doses of a "nonionic" iodinated contrast agent.


Asunto(s)
Medios de Contraste/efectos adversos , Enfermedades Renales/inducido químicamente , Enfermedades Renales/epidemiología , Tomografía Computarizada por Rayos X , Adulto , Anciano , Anciano de 80 o más Años , Femenino , Humanos , Incidencia , Masculino , Persona de Mediana Edad , Estudios Prospectivos , Tomografía Computarizada por Rayos X/métodos , Adulto Joven
5.
J Chromatogr A ; 1559: 95-101, 2018 Jul 20.
Artículo en Inglés | MEDLINE | ID: mdl-29290398

RESUMEN

Nine organophosphorus pesticides (OPPs) were determined in environmental waters from different origins using in situ ionic liquid dispersive liquid microextraction (IL-DLLME). This preconcentration technique was coupled to gas chromatography-mass spectrometry (GC-MS) using microvial insert thermal desorption, an approach that uses a thermal desorption injector as sample introduction system. The parameters affecting both the microextraction and sample injection steps were optimized. The proposed method showed good precision, with RSD values ranging from 4.1 to 9.7%, accuracy with recoveries in the 85-118% range, and sensitivity with DLs ranging from 5 to 16 ng L-1.


Asunto(s)
Cromatografía de Gases y Espectrometría de Masas , Microextracción en Fase Líquida , Compuestos Organofosforados/análisis , Plaguicidas/análisis , Líquidos Iónicos/química , Compuestos Organofosforados/aislamiento & purificación , Plaguicidas/aislamiento & purificación
6.
J Chromatogr A ; 1475: 74-79, 2016 Dec 02.
Artículo en Inglés | MEDLINE | ID: mdl-27839755

RESUMEN

A solventless analytical method is proposed for analyzing the compounds responsible for cork taint in cork stoppers. Direct sample introduction (DSI) is evaluated as a sample introduction system for the gas chromatography-mass spectrometry (GC-MS) determination of four haloanisoles (HAs) in cork samples. Several parameters affecting the DSI step, including desorption temperature and time, gas flow rate and other focusing parameters, were optimized using univariate and multivariate approaches. The proposed method shows high sensitivity and minimises sample handling, with detection limits of 1.6-2.6ngg-1, depending on the compound. The suitability of the optimized procedure as a screening method was evaluated by obtaining decision limits (CCα) and detection capabilities (CCß) for each analyte, which were found to be in 6.9-11.8 and 8.7-14.8ngg-1, respectively, depending on the compound. Twenty-four cork samples were analysed, and 2,4,6-trichloroanisole was found in four of them at levels between 12.6 and 53ngg-1.


Asunto(s)
Anisoles/análisis , Cromatografía de Gases y Espectrometría de Masas/métodos , Vino
7.
Talanta ; 160: 282-288, 2016 Nov 01.
Artículo en Inglés | MEDLINE | ID: mdl-27591615

RESUMEN

A sensitive analytical procedure for the determination of four haloanisoles (2,4,6 trichloroanisole, 2,4,6-tribromoanisole, 2,3,4,6-tetrachloroanisole and pentachloroanisole) related with cork taint defects in wines, in different types of alcoholic beverages has been developed. The analytes were extracted from the matrix samples by cloud point extraction (CPE) using Triton X-114 heated to 75°C, and the surfactant rich phase was separated by centrifugation. By means of direct microvial insert thermal desorption, 20µL of the CPE obtained extract was submitted to gas chromatography-mass spectrometry (GC-MS) analysis. The parameters affecting the CPE and microvial insert thermal desorption were optimized. Quantification was carried by matrix-matched calibration using an internal standard. Detection limits ranged between 12.9 and 20.8ngL(-1), depending on the compound, for beer and wine samples, whereas for whiskies values in the 46.3-48ngL(-1) range were obtained, since these samples were diluted for analysis. Recoveries for alcoholic beverages were in the 89-111% range, depending on the analyte and the sample.


Asunto(s)
Bebidas Alcohólicas/análisis , Anisoles/análisis , Cromatografía de Gases y Espectrometría de Masas , Calor , Madera
8.
J Chromatogr A ; 1456: 27-33, 2016 Jul 22.
Artículo en Inglés | MEDLINE | ID: mdl-27317004

RESUMEN

A rapid and sensitive procedure for the determination of six NPs in soils by gas chromatography and mass spectrometry (GC-MS) is proposed. Ultrasound assisted extraction (UAE) is used for NP extraction from soil matrices to an organic solvent, while the environmentally friendly technique dispersive liquid-liquid microextraction (DLLME) is used for the preconcentration of the resulting UAE extracts. NPs were derivatized by applying an "in-situ" acetylation procedure, before being injected into the GC-MS system using microvial insert large volume injection (LVI). Several parameters affecting UAE, DLLME, derivatization and injection steps were investigated. The optimized procedure provided recoveries of 86-111% from spiked samples. Precision values of the procedure (expressed as relative standard deviation, RSD) lower than 12%, and limits of quantification ranging from 1.3 to 2.6ngg(-1), depending on the compound, were obtained. Twenty soil samples, obtained from military, industrial and agricultural areas, were analyzed by the proposed method. Two of the analytes were quantified in two of the samples obtained from industrial areas, at concentrations in the 4.8-9.6ngg(-1) range.


Asunto(s)
Nitrofenoles/análisis , Contaminantes del Suelo/análisis , Suelo/química , Cromatografía de Gases y Espectrometría de Masas/métodos , Microextracción en Fase Líquida/métodos , Metanol , Solventes , Ondas Ultrasónicas
9.
Neurologia ; 31(3): 183-94, 2016 Apr.
Artículo en Inglés, Español | MEDLINE | ID: mdl-26383062

RESUMEN

INTRODUCTION: Brief cognitive tests (BCT) may help detect cognitive impairment (CI) in the clinical setting. Several BCT have been developed and/or validated in our country, but we lack specific recommendations for use. DEVELOPMENT: Review of studies on the diagnostic accuracy of BCT for CI, using studies conducted in Spain with BCT which take less than 20 min. We provide recommendations of use based on expert consensus and established on the basis of BCT characteristics and study results. CONCLUSION: The Fototest, the Memory Impairment Screen (MIS) and the Mini-Mental State Examination (MMSE) are the preferred options in primary care; other BCT (Clock Drawing Test [CDT], test of verbal fluency [TVF]) may also be administered in cases of negative results with persistent suspected CI or concern (stepwise approach). In the specialised care setting, a systematic assessment of the different cognitive domains should be conducted using the Montreal Cognitive Assessment, the MMSE, the Rowland Universal Dementia Assessment, the Addenbrooke's Cognitive Examination, or by means of a stepwise or combined approach involving more simple tests (CDT, TVF, Fototest, MIS, Memory Alteration Test, Eurotest). Associating an informant questionnaire (IQ) with the BCT is superior to the BCT alone for the detection of CI. The choice of instruments will depend on the patient's characteristics, the clinician's experience, and available time. The BCT and IQ must reinforce - but never substitute - clinical judgment, patient-doctor communication, and inter-professional dialogue.


Asunto(s)
Trastornos del Conocimiento/diagnóstico , Trastornos del Conocimiento/psicología , Cognición , Pruebas Neuropsicológicas , Anciano , Anciano de 80 o más Años , Demencia/diagnóstico , Femenino , Humanos , Masculino , Persona de Mediana Edad , Reproducibilidad de los Resultados
10.
J Chromatogr A ; 1399: 18-24, 2015 Jun 19.
Artículo en Inglés | MEDLINE | ID: mdl-25958092

RESUMEN

Headspace sorptive extraction (HSSE) was used to preconcentrate seven monoterpenes (eucalyptol, linalool, menthol, geraniol, carvacrol, thymol and eugenol) for separation by gas chromatography and mass spectrometry (GC-MS). Three commercially available coatings for the stir bars, namely Polydimethylsiloxane (PDMS), polyacrilate (PA) and Ethylene glycol-silicone (EG-Silicone), were tested, and the influential parameters both in the adsorption and the thermal desorption steps were optimized. PDMS provided the best sensitivity for linalool, geraniol, menthol and eucalyptol, whereas EG-Silicone was best for extracting the phenolic monoterpenes studied. Considering the average obtained slopes from all compounds, PDMS pointed as the best option, and the analytical characteristics for the HSSE-TD-GC-MS method using this coating were obtained. Quantification of the samples was carried out by matrix-matched calibration using a synthetic honey. Detection limits ranged between 0.007 and 0.032 ng g(-1), depending on the compound. Twelve honey samples of different floral origins were analyzed using the HSSE-GC-MS method, the analytes being detected at concentrations up to 64 ng g(-1).


Asunto(s)
Análisis de los Alimentos/métodos , Cromatografía de Gases y Espectrometría de Masas , Miel/análisis , Terpenos/análisis , Adsorción , Análisis de los Alimentos/instrumentación , Siliconas/química
11.
J Chromatogr A ; 1380: 156-61, 2015 Feb 06.
Artículo en Inglés | MEDLINE | ID: mdl-25582486

RESUMEN

A method using direct sample introduction (DSI) coupled to gas chromatography-mass spectrometry (GC-MS) is developed for the determination of six phthalate esters (dimethyl, diethyl, dibutyl, butylbenzyl, diethylhexyl and dioctyl phthalate) in cleaning products. The different variables involved in the DSI step, including venting time and temperature, vaporisation time and temperature, injector heating temperature and gas flow rate and pressure, were evaluated and optimised using Taguchi orthogonal arrays. The proposed method, using calibration against methanolic standards, showed good linearity in the 0.05-15 µg g(-1) range and good repeatability, with RSD values ranging from 3.5% to 5.7%. Quantification limits between 0.010 and 0.041 µg g(-1), depending on the compound, were attained, while recovery assays provided values from 83% to 115%. Twenty-seven cleaning products were analysed using the DSI-GC-MS method, being four phthalates (dimethyl, diethyl, dibutyl and diethylhexyl phthalate) found in fourteen of them at concentration levels in the 0.1-21 µg g(-1) range. Compared with the most common GC injection technique, which uses the split/splitless injector, the proposed DSI procedure provided larger peak areas and lower detection limits, as result of the greater injected volume and reduction in noise.


Asunto(s)
Ácidos Ftálicos/análisis , Tensoactivos/química , Detergentes/química , Dietilhexil Ftalato/análisis , Ésteres , Cromatografía de Gases y Espectrometría de Masas/métodos , Límite de Detección , Temperatura
12.
Actas Urol Esp ; 38(10): 678-84, 2014 Dec.
Artículo en Inglés, Español | MEDLINE | ID: mdl-24984581

RESUMEN

CONTEXT: Beta-lactamases are bacterial enzymes that protect microorganisms from the lethal effects of ß-lactam antibiotics. The production of beta-lactamases is the most important mechanism of resistance to these antibiotics, especially in Gram-negative bacteria. OBJECTIVE: Review the magnitude of the problem of extended-spectrum beta-lactamases (ESBL) in the urological setting and present the fundamental action guidelines on the issue, the main risk factors and the prevention strategies. ACQUISITION OF EVIDENCE: A structured search strategy for patient, problem, intervention, comparison and result was conducted in the PubMed-Medline database to identify the most relevant studies related to the management of patients with urinary tract infection by ESBL-producing microorganisms. We also present a caseload analysis of our center on this issue. SUMMARY OF THE EVIDENCE: ESBL are found in Enterobacteria, mainly Klebsiella sp. and Escherichia coli and are characterized by their hydrolytic ability compared with beta-lactam antibiotics, which entails resistance to penicillin, cephalosporin and aztreonam. They are also associated with resistance to other antibiotics. There is a high risk of infection and colonization by ESBL producers in patients with prolonged hospital stays or who required invasive devices. The prior use of antibiotics and stays in residential care are also risk factors. Prevention programs should focus on preventing nosocomial infection. It is essential that a restrictive policy on the use of antibiotics be implemented. The therapy of choice for severe infections is focused on carbapenems, although their indiscriminate use should be avoided. In uncomplicated lower urinary tract infections, fosfomycin and nitrofurantoin are the best treatment alternatives. CONCLUSION: ESBL-producing strains constitute a true global health problem. Prevention strategies should focus on nosocomial infection. We should not forget, however, that the appearance of these pathogens in community-acquired infections is increasingly frequent. Therapeutic decisions should be based on an understanding of the local distribution of microorganisms and their resistance patterns.


Asunto(s)
Antibacterianos/uso terapéutico , Infecciones por Enterobacteriaceae/tratamiento farmacológico , Infecciones Urinarias/tratamiento farmacológico , Antibacterianos/farmacología , Infección Hospitalaria , Enterobacteriaceae/efectos de los fármacos , Enterobacteriaceae/enzimología , Humanos , Guías de Práctica Clínica como Asunto , beta-Lactamasas
13.
J Chromatogr A ; 1356: 38-44, 2014 Aug 22.
Artículo en Inglés | MEDLINE | ID: mdl-25001331

RESUMEN

A solvent-free method is described for the determination of 10 volatile polycyclic aromatic hydrocarbons (PAHs), considered as priority pollutants by the EU, in different herbal infusions using headspace sorptive extraction (HSSE) and gas chromatography-mass spectrometry (GC-MS). The parameters affecting both the extraction and thermal desorption steps in the HSSE were optimized by means of Plackett-Burman designs. Ten millilitres of the herbal infusion was submitted to the HSSE preconcentration in the presence of salt for 4h at 88 °C. The use of d(10)-phenanthrene as internal standard not only improved the repeatability of the method but allowed quantification of the samples against external aqueous standards. Detection limits ranged between 11 and 26 ng L(-1).


Asunto(s)
Bebidas/análisis , Cromatografía de Gases y Espectrometría de Masas , Hidrocarburos Policíclicos Aromáticos/análisis , Adsorción , Manzanilla/química , Reproducibilidad de los Resultados , Algas Marinas/química , Solventes
14.
Forensic Sci Int ; 238: 26-32, 2014 May.
Artículo en Inglés | MEDLINE | ID: mdl-24631666

RESUMEN

A novel method for separation and identification of ignitable liquid residues in fire debris by gas chromatography and mass spectrometry is presented. Preconcentration of the analytes was carried out using the simple headspace sorptive extraction (HSSE) technique. Polydimethylsiloxane stir bars were used as the enrichment phase, and parameters affecting both the adsorption and desorption stages were carefully optimized. Extraction was carried out at 50°C for 1h. Stir bars were desorbed thermally in the GC injection port, thus avoiding the use of organic solvents. The results for five ignitable liquids, including gasoline and diesel fuel, using HSSE were compared with those obtained with a solid-phase microextraction method, with HSSE appearing as a more sensitive alternative.

15.
J Chromatogr A ; 1315: 21-7, 2013 Nov 08.
Artículo en Inglés | MEDLINE | ID: mdl-24075014

RESUMEN

A simple and highly sensitive procedure based on stir bar sorptive extraction coupled to gas chromatography-mass spectrometry by means of a thermal desorption unit (SBSE-TD-GC-MS) has been optimized for the determination of cis/trans isomers of resveratrol, piceatannol and oxyresveratrol in wine samples. Quantification of the cis-isomers was carried out by generating the standards from the corresponding trans-species once they had been preconcentrated on the SBSE extracting phase. The optimization of the acetylation derivatization, SBSE extraction and thermal desorption steps was investigated using Plackett-Burman designs, taking into account the high number of variables to be considered. The use of bisphenol F as internal standard allowed quantification of the samples against aqueous standards. Repeatability, expressed as relative standard deviation of 10 successive analyses was between 5% and 9%, confirming the high precision attained under the optimized conditions. Satisfactory recovery values of between 79% and 109% were obtained for spiked samples in the 0.2-1.0 µgL(-1) concentration range, depending on the compound. The main compound determined in the analyzed samples was trans-resveratrol, with concentrations in the range of 3-230 µgL(-1), depending on the type of wine.


Asunto(s)
Fraccionamiento Químico/métodos , Cromatografía de Gases y Espectrometría de Masas/métodos , Estilbenos/análisis , Vino/análisis , Análisis de Regresión , Reproducibilidad de los Resultados , Sensibilidad y Especificidad , Estereoisomerismo , Estilbenos/aislamiento & purificación
16.
J Chromatogr A ; 1279: 1-6, 2013 Mar 01.
Artículo en Inglés | MEDLINE | ID: mdl-23357745

RESUMEN

A method based on headspace sorptive extraction (HSSE) in combination with thermal desorption-gas chromatography-mass spectrometry (TD-GC-MS) has been developed for the simultaneous determination of six organotin compounds (OTCs), corresponding to mono- and di-substituted methyltin, butyltin and octyltin species. Several parameters affecting both the headspace extraction and thermal desorption steps were carefully optimized using multivariate designs. Analytes were derivatized by in situ ethylation with sodium tetraethylborate. The optimized method was applied to the analysis of water samples of different origins, as well as to checking the migration of the studied compounds from commercially available plastic containers to the adequate liquid simulant. Quantification was carried out against aqueous calibration curves using diphenyltin as internal standard, providing detection limits of between 1.7 and 7.0 ng(Sn) L(-1), depending on the compound, and repeatabilities lower than 10% in terms of relative standard deviation. The applicability of the method was assessed by means of recovery studies and satisfactory values for all compounds were attained. The release of OTCs from the tested packages to the liquid simulant was confirmed, concentrations as high as 2.4 µg(Sn) L(-1) being found for dioctyltin. Even though the proposed method was developed for organotin halides, its application to an organotin ester shows its suitability for determining these compounds in migration assays.


Asunto(s)
Compuestos Orgánicos de Estaño/aislamiento & purificación , Microextracción en Fase Sólida/métodos , Contaminantes Químicos del Agua/aislamiento & purificación , Adsorción , Cromatografía de Gases y Espectrometría de Masas , Compuestos Orgánicos de Estaño/química , Agua de Mar/química , Contaminantes Químicos del Agua/química
17.
J Chromatogr A ; 1247: 146-53, 2012 Jul 20.
Artículo en Inglés | MEDLINE | ID: mdl-22682950

RESUMEN

This paper describes a method for the simultaneous determination of bisphenol A (BPA), bisphenol F (BPF), bisphenol Z (BPZ) and biphenol (BP), using stir bar sorptive extraction (SBSE) in combination with thermal desorption-gas chromatography-mass spectrometry (TD-GC-MS). Several parameters affecting both extraction and thermal desorption of the SBSE stages were carefully optimized by multivariate designs. SBSE was performed with two derivatization procedures, in situ acetylation and in tube silylation, and the results were compared with those obtained when the analytes were not derivatized. The proposed method, determining the analytes as acyl derivatives, was applied to analyze commercially canned beverages, as well as the filling liquids of canned vegetables, providing detection limits of between 4.7 and 12.5 ng L⁻¹, depending on the compound. The intraday and interday precisions were lower than 6% in terms of relative standard deviation. Recovery studies at two concentration levels, 0.1 and 1 µg L⁻¹, were performed providing recoveries in the 86-122% range. The samples analyzed contained higher concentrations of BPA than of the other analytes.


Asunto(s)
Compuestos de Bencidrilo/análisis , Bebidas/análisis , Fraccionamiento Químico/métodos , Ciclohexanos/análisis , Alimentos en Conserva/análisis , Cromatografía de Gases y Espectrometría de Masas/métodos , Fenoles/análisis , Anhídridos Acéticos/química , Carbonatos/química , Fraccionamiento Químico/instrumentación , Límite de Detección , Reproducibilidad de los Resultados , Cloruro de Sodio/química , Compuestos de Trimetilsililo/química
18.
ScientificWorldJournal ; 2012: 605610, 2012.
Artículo en Inglés | MEDLINE | ID: mdl-22645438

RESUMEN

Formulation process is a very complex activity which sometimes implicates taking decisions about parameters or variables to obtain the best results in a high variability or uncertainty context. Therefore, robust optimization tools can be very useful for obtaining high quality formulations. This paper proposes the optimization of different responses through the robust Taguchi method. Each response was evaluated like a noise variable, allowing the application of Taguchi techniques to obtain a response under the point of view of the signal to noise ratio. A L(18) Taguchi orthogonal array design was employed to investigate the effect of eight independent variables involved in the formulation of alginate-Carbopol beads. Responses evaluated were related to drug release profile from beads (t(50%) and AUC), swelling performance, encapsulation efficiency, shape and size parameters. Confirmation tests to verify the prediction model were carried out and the obtained results were very similar to those predicted in every profile. Results reveal that the robust optimization is a very useful approach that allows greater precision and accuracy to the desired value.


Asunto(s)
Resinas Acrílicas/química , Alginatos/química , Química Farmacéutica/métodos , Resinas Acrílicas/administración & dosificación , Alginatos/administración & dosificación , Algoritmos , Cationes , Preparaciones de Acción Retardada , Composición de Medicamentos/métodos , Sistemas de Liberación de Medicamentos , Ácido Glucurónico/administración & dosificación , Ácido Glucurónico/química , Ácidos Hexurónicos/administración & dosificación , Ácidos Hexurónicos/química , Microscopía Electrónica de Rastreo/métodos , Microesferas , Modelos Estadísticos , Polímeros/química , Reproducibilidad de los Resultados , Relación Señal-Ruido , Temperatura
19.
J Chromatogr A ; 1241: 21-7, 2012 Jun 08.
Artículo en Inglés | MEDLINE | ID: mdl-22533911

RESUMEN

This paper describes a method for the determination of three alkylphenols (APs), 4-tert-octylphenol (tOP), 4-n-octylphenol (OP) and 4-nonylphenol (NP), and six phthalate esters (PEs), dimethylphthalate (DMP), diethylphthalate (DEP), di-n-butylphthalate (DBP), n-butylbenzylphthalate (BBP), di-2-ethylhexylphthalate (DEHP) and di-n-octylphthalate (DOP), in vegetables using stir bar sorptive extraction (SBSE) in combination with thermal desorption-gas chromatography-mass spectrometry (TD-GC-MS). Ultrasonic radiation was used to extract the analytes from the solid food matrix, and the extract obtained was preconcentrated by SBSE. The different parameters affecting both stages were carefully optimized. The method was applied to analyze commercial vegetables, in the form of plastic packed salads and canned greens, as well as the corresponding filling liquids of the canned food. Quantification of the samples was carried out against aqueous standards using an internal standard (anthracene). The analysis of a 2 g vegetable sample provided detection limits between 12.7 and 105.8 pg g⁻¹ for OP and DEHP, respectively. Migration studies from the plastic packages of the vegetables samples analyzed were carried out. DEP, DBP and DEHP were found to have migrated from the bags to the simulant and the same compounds were quantified in lettuce, corn salad, arugula, parsley and chard, at concentration levels in the 8-51 ng g⁻¹ range. However, OP and NP were found in only two vegetable samples and one filling liquid, but neither was detected in any package. The proposed method provided recoveries of 83-118%.


Asunto(s)
Fraccionamiento Químico/métodos , Embalaje de Alimentos , Cromatografía de Gases y Espectrometría de Masas/métodos , Fenoles/análisis , Ácidos Ftálicos/análisis , Verduras/química , Ésteres/análisis , Ésteres/aislamiento & purificación , Modelos Lineales , Fenoles/aislamiento & purificación , Ácidos Ftálicos/aislamiento & purificación , Presión , Reproducibilidad de los Resultados , Factores de Tiempo
20.
Food Sci Technol Int ; 18(2): 103-12, 2012 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-22377626

RESUMEN

The aim of the present paper is to compare the behaviour of industrial lactic bacteria and indigenous bacteria of the cellar when malolactic fermentation was carried out in barrels. The effects of these bacteria on the concentration of metabolised amino acids during malolactic fermentation and on the composition of volatile compounds both before and after malolactic fermentation are studied. The experiment was performed with wines of the Tempranillo and Cabernet Sauvignon varieties. An analysis has been made of the easily extractable volatile compounds of the wood and the compounds from the grapes, and the action of the yeasts during the alcoholic fermentation. Acetoin and diacetyl decreased during the malolactic fermentation in barrels and the concentrations of furfural and its derivatives were up to 100 times higher in wines not subjected to malolactic fermentation. Most of the volatile phenols increased during the malolactic fermentation in wines of the Tempranillo variety, while only guaiacol (p < 0.05) and t-isoeugenol increased in the Cabernet Sauvignon wines. The decrease in amino acids during the malolactic fermentation depends much more on the variety than on the bacterial strain which carries out the malolactic fermentation.


Asunto(s)
Aminoácidos/química , Fermentación , Lactobacillus/metabolismo , Malato Deshidrogenasa/metabolismo , Compuestos Orgánicos Volátiles/química , Vino/análisis , Tecnología de Alimentos
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