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AIM: To compare how parents' attitudes, knowledge, and sociodemographic characteristics influence untreated early childhood caries in infants and preschoolers in Brazil and Colombia. BACKGROUND: Dental caries is a prevalent chronic disease affecting children worldwide. However, little research has explored the connection between parents' knowledge, attitudes, and beliefs about oral health and the occurrence of dental caries in their children's primary teeth. MATERIALS: Oral health information was evaluated in children aged 3 to 5 years with a questionnaire covering sociodemographic and socioeconomic variables, family information and questions about health knowledge and child's and parents' oral health. In addition, oral examinations have been carried out to determine the prevalence of untreated dental caries. A p-value of 0.05 and 95% reliability level were considered statistically significant. CONCLUSION: Untreated caries in infants and preschoolers are influenced by socioeconomic status, maternal education, sugar consumption, oral hygiene, and parents' beliefs about primary dentition.
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While current trends in Green Analytical Chemistry aim at reducing or simplifying sample treatment, food usually comprises complex matrices where direct analysis is not possible in most cases. In this context, sample treatment plays a pivotal role. Biogenic amines are naturally formed in many foodstuffs due to the action of microorganisms, while their presence has been associated with adverse health effects. In this work, the extraction of seven biogenic amines (cadaverine, histamine, phenylethylamine, putrescine, spermidine, spermine, and tyramine) from beer samples has been simplified using laboratory filter paper as sorbent without any further modification. The analysis of the eluates by direct infusion mass spectrometry reduces the time of analysis, increasing the sample throughput. This simple but effective method enabled the determination of the analytes with limits of detection as low as 0.06 mg L-1 and relative standard deviations better than 11.9%. The suitability of the method has been assessed by analyzing eight different types of beers by the standard addition method.
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Cerveja/análise , Aminas Biogênicas/isolamento & purificação , Celulose/química , Filtração , Adsorção , Aminas Biogênicas/química , Calibragem , Concentração de Íons de Hidrogênio , Concentração Osmolar , Papel , Padrões de Referência , Espectrometria de Massas em Tandem/métodosRESUMO
Congenital central hypoventilation syndrome (CCHS) and rapid-onset obesity syndrome with hypothalamic dysfunction, hypoventilation, and autonomic dysregulation (ROHHAD) are rare causes of hypoventilation during sleep in the pediatric population. This group of disorders are characterized by the absence or decrease in the automatic control of ventilation, decreased sensitivity of chemoreceptors to CO2, causing hypoventilation during sleep and even in wakefulness, in the most severe cases. For these reasons it is important to diagnose and treat them promptly. The objective of this review is to provide current and complete literature, to be able to identify, treat and refer this group of children early, and thus reduce the complications and/or associated comorbidities in the short and long term, improving their quality of life.
El síndrome de hipoventilación central congénita (CCHS) y síndrome de obesidad de inicio rápido con disfunción hipotalámica, hipoventilación y desregulación autonómica (ROHHAD), son causas poco comunes de hipoventilación durante el sueño en la población pediátrica. Este grupo de trastornos se caracterizan por ausencia o disminución en el control automático de la ventilación, sensibilidad disminuida de los quimioreceptores al CO2, provocando hipoventilación durante el sueño e incluso en vigilia, en los casos más severos. Por estas razones es importante diagnosticarlos y tratarlos oportunamente. El objetivo de esta revisión es proporcionar literatura actual y completa, para poder identificar, tratar y referir a éste grupo de niños tempranamente, y así disminuir las complicaciones y/o comorbilidades asociadas a corto y largo plazo, mejorando su calidad de vida.
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Humanos , Criança , Síndrome de Hipoventilação por Obesidade/fisiopatologia , Transtornos do Sono-Vigília/fisiopatologia , Hipoventilação/fisiopatologia , Síndrome de Hipoventilação por Obesidade/complicações , Prognóstico , Respiração Artificial , Sono , Transtornos do Sono-Vigília/diagnóstico , Transtornos do Sono-Vigília/etiologia , Transtornos do Sono-Vigília/terapia , Polissonografia , Hipoventilação/complicações , Hipoventilação/congênito , Hipoventilação/diagnóstico , Hipoventilação/terapiaRESUMO
The simplification of the analytical procedures, including cost-effective materials and detectors, is a current research trend. In this context, paper has been identified as a useful material thanks to its low price and high availability in different compositions (office, filter, chromatographic). Its porosity, flexibility, and planar geometry permit the design of flow-through devices compatible with most instrumental techniques. This article provides a general overview of the potential of paper, as substrate, on the simplification of analytical chemistry methodologies. The design of paper-based sorptive phases is considered in-depth, and the different functionalization strategies are described. Considering our experience in sample preparation, special attention has been paid to the use of these phases under the classical microextraction-analysis workflow, which usually includes a chromatographic separation of the analytes before their determination. However, the interest of these materials extends beyond this field as they can be easily implemented into spectroscopic and electrochemical sensors. Finally, the direct analysis of paper substrates in mass spectrometry, in the so-called paper-spray technique is also discussed. This review is more focused on presenting ideas rather than the description of specific applications to draw a general picture of the potential of these materials.
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Cotton is a natural material with good mechanical and chemical properties. It presents a hydrophilic surface that must be modified by the introduction of appropriate groups, if semi-polar or non-polar analytes are intended to be isolated from an aqueous matrix. In this article, cotton is modified with ß-cyclodextrins, which presents a hydrophobic cavity where target molecules can be hosted. The cavity size restricts the access of larger or less accessible molecules due to their conformation, thus improving the extraction selectivity. The modified cotton fibers are packed in a disposable syringe device where all the steps of the extraction take place. The ensuing fibers were evaluated for the extraction of several drugs providing the best results for cocaine (CO) and methamphetamine (MTA). These targets were extracted from saliva samples and finally determined by direct infusion mass spectrometry. The method provides limits of detection and quantification of 0.6 and 2 µg L-1 for CO and 0.8 and 2.7 µg L-1 for MTA, with precision values at the quantification level better than the 9% (expressed as relative standard deviation). Also, relative recoveries ranged from 115% to 111% for CO and MTA, respectively, demonstrating the applicability of the proposed method. Matrix effect, which has been statistically evaluated, is not significant, showing that the extraction selectivity can compensate the circumvent of the chromatographic separation.
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Cocaína , Metanfetamina , beta-Ciclodextrinas , Fibra de Algodão , Espectrometria de Massas , SalivaRESUMO
Lectin is considered as a suitable biomarker for nano-depletion of acrosome-damaged sperm. The aim of this study was to synthetize magnetic nanoparticles (MNPs) coated by peanut (Arachis hypogaea) agglutinin lectin (PNA) and investigate its beneficial effect in improving of sperm characteristics. MNPs were obtained by co-precipitation method, functionalized with chitosan and coated by PNA at a concentration of 0.04 mg/mL. Semen was frozen either with glycerol-based or sucrose-based extenders. Frozen-thawed straws from five donkeys (three ejaculates per donkey) were incubated with lectin-MNPs (2 mg/mL), and then exposed to an external magnet enabling the non-bound sperm to be collected as nanopurified sperm. Sperm were evaluated post-thawing (control) and after nanopurification for motility, plasma membrane integrity, acrosome integrity, morphology, DNA fragmentation and concentration. The statistical analyses were extended to investigate the correlation between the initial quality of the frozen-thawed semen samples and the effect of nanopurification after thawing. The obtained MNPs were biocompatible to the sperm and significantly improved the progressive motility (P < 0.05) for the glycerol nanopurified group (43.08 ± 3.52%) in comparison to control (33.70 ± 2.64%). Acrosome-damaged sperm were reduced (P < 0.05) in both nanopurified groups (19.92 ± 2.69 for G and 21.57 ± 2.77 for S) in comparison to control (36.07 ± 3.82 for G and 35.35 ± 3.88 for S). There were no significant changes in sperm morphology and membrane integrity after nanopurification. The average sperm recovery after nanopurification was 80.1%. Sperm quality index was significantly higher (P < 0.001) in nanopurified groups regardless of the initial quality of the frozen thawed semen samples. However, in the high sperm quality group, nanopurification significantly improved the progressive motility and membrane integrity besides the increasing of acrosome-intact sperm. Sperm nanopurification using lectin-magnetic nanoparticles can be considered as a suitable method to reduce the proportion of acrosome-damaged sperm and to increase the quality of frozen thawed donkey semen.
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Acrossomo/patologia , Equidae , Lectinas , Nanopartículas de Magnetita , Aglutinina de Amendoim , Espermatozoides , Animais , Criopreservação/métodos , Criopreservação/veterinária , Crioprotetores/farmacologia , Fragmentação do DNA , Glicerol/farmacologia , Masculino , Análise do Sêmen , Sacarose/farmacologiaRESUMO
Paper-based analytical devices (PADs) have encountered a wealth of applications in recent years thanks to the numerous advantages of paper as a support. A silver nanoflower (AgNF) modified paper-based dual substrate for both surface-enhanced Raman spectroscopy (SERS) and ambient pressure paper spray mass spectrometry (PS-MS) was developed. AgNFs were immobilized on nylon-coated paper modified with silver and ethylenediamine. The developed substrate was characterized via scanning electron microscopy and infrared spectroscopy. The densely packed nanoscale petals of the AgNFs lead to a large number of so-called hot spots at their overlapping points, which result in an enhancement of the Raman signal. In addition, the presence of the AgNFs produces an increase in the sensitivity of the mass spectrometric analysis as compared with bare paper and nylon/Ag-coated paper. The dual substrate was evaluated for the identification and quantification of ketoprofen in aqueous standards as well as human saliva from healthy volunteers. The method enables the determination of ketoprofen with a limit of detection and limit of quantification via PS-MS of 0.023 and 0.076 mg L-1, respectively, with a relative standard deviation (RSD) of 3.4% at a concentration of 0.1 mg L-1. This dual substrate enables the simple and fast detection of ketoprofen with minimal sample preparation, providing complementary Raman and mass spectrometric information. Graphical abstract.
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Aim: This study aimed to evaluate differences in tactile acuity (TA) in people with non-specific persistent low back pain (NSPLBP) with and without predominant central sensitisation (CS).Method: An analytical cross-sectional study was conducted with 45 participants divided into three groups: (i) subjects with NSPLBP with predominant CS (n = 14), (ii) subjects with NSPLBP without predominant CS (n = 16) and (iii) subjects without low back pain (n = 15). Using an analogue calliper, TA was measured using the two-point discrimination threshold (TPD) in the three groups, both horizontally and vertically in the painful region. The analysis was based on the comparison of median discrimination thresholds between groups using the Kruskal-Wallis test.Result: A higher median TPD value was observed in the group with NSPLBP with predominant CS (vertical measurement 37.5 mm; horizontal measurement 52.5 mm) compared to the group with NSPLBP without predominant CS (vertical measurement 32.5 mm; horizontal measurement 33.8 mm) and the group without low back pain (vertical measurement 30 mm; horizontal measurement 27.5 mm) (p < 0.0001), both in vertical and horizontal measurement.Conclusion: The findings found in this study highlight the need to differentiate patients with NSPLBP with predominant CS when considering therapeutic evaluation as an indirect mechanism for assessing the perceptual function of the primary somatosensory cortex.
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Sensibilização do Sistema Nervoso Central/fisiologia , Discriminação Psicológica/fisiologia , Dor Lombar/fisiopatologia , Limiar Sensorial/fisiologia , Percepção do Tato/fisiologia , Adulto , Estudos Transversais , Feminino , Humanos , Masculino , Pessoa de Meia-IdadeRESUMO
Bovine leukaemia virus (BLV) is the causative agent of enzootic bovine leucosis, which has been reported worldwide. BLV has been found recently in human tissue and it could have a significant impact on human health. A possible hypothesis regarding viral entry to humans is through the consumption of infected foodstuffs. This study was aimed at detecting the presence of BLV DNA in raw beef and fresh milk for human consumption. Nested PCR directed at the BLV gag gene (272 bp) was used as a diagnostic test. PCR products were confirmed by Sanger sequencing. Forty-nine per cent of the samples proved positive for the presence of proviral DNA. This is the first study highlighting the presence of the BLV gag gene in meat products for human consumption and confirms the presence of the viral DNA in raw milk, as in previous reports. The presence of viral DNA in food products could suggest that viral particles may also be found. Further studies are needed to confirm the presence of infected viral particles, even though the present findings could represent a first approach to BLV transmission to humans through foodstuff consumption.
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DNA Viral/genética , Leucose Enzoótica Bovina/transmissão , Vírus da Leucemia Bovina , Carne/virologia , Leite/virologia , Animais , Bovinos , Humanos , Vírus da Leucemia Bovina/genética , Reação em Cadeia da Polimerase Multiplex , Reação em Cadeia da Polimerase , Análise de Sequência de DNAAssuntos
Anticonvulsivantes/uso terapêutico , Análise Química do Sangue/instrumentação , Hipernatremia/diagnóstico , Sódio/sangue , Tiopental/uso terapêutico , Anticonvulsivantes/efeitos adversos , Criança , Pré-Escolar , Epilepsia Resistente a Medicamentos/tratamento farmacológico , Epilepsia Resistente a Medicamentos/etiologia , Reações Falso-Positivas , Feminino , Humanos , Hipertensão Intracraniana/complicações , Masculino , Tiopental/efeitos adversosRESUMO
In April 2015, the Spanish National Health System (SNHS) developed a national strategic plan for the diagnosis, treatment, and management of hepatitis C virus (HCV). Our aim was to analyze the impact of this on human immunodeficiency virus (HIV)-infected patients included in the HERACLES cohort during the first 6 months of its implementation. The HERACLES cohort (NCT02511496) was set up in March 2015 to evaluate the status and follow-up of chronic HCV infection in patients co-infected with HIV in the south of Spain. In September 2015, the data were analyzed to identify clinical events (death, liver decompensation, and liver fibrosis progression) and rate of treatment implementation in this population. The study population comprised a total of 3474 HIV/HCV co-infected patients. The distribution according to liver fibrosis stage was: 1152 F0-F1 (33.2 %); 513 F2 (14.4 %); 641 F3 (18.2 %); 761 F4 (21.9 %); and 407 whose liver fibrosis was not measured (12.3 %). During follow-up, 248 patients progressed by at least one fibrosis stage [7.1 %; 95 % confidence interval (CI): 6.3-8 %]. Among cirrhotic patients, 52 (6.8 %; 95 % CI: 5.2-8.9 %) developed hepatic decompensation. In the overall population, 50 patients died (1.4 %; 95 % CI: 1.1-1.9 %). Eight hundred and nineteen patients (23.56 %) initiated interferon (IFN)-free treatment during follow-up, of which 47.8 % were cirrhotic. In our study, during 6 months of follow-up, 23.56 % of HIV/HCV co-infected patients included in our cohort received HCV treatment. However, we observed a high incidence of negative short-term outcomes in our population.
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Antivirais/uso terapêutico , Infecções por HIV/complicações , Acessibilidade aos Serviços de Saúde , Hepatite C Crônica/complicações , Hepatite C Crônica/tratamento farmacológico , Cirrose Hepática/epidemiologia , Falência Hepática/epidemiologia , Adulto , Idoso , Feminino , Política de Saúde , Hepatite C Crônica/diagnóstico , Hepatite C Crônica/mortalidade , Humanos , Cirrose Hepática/patologia , Falência Hepática/patologia , Masculino , Pessoa de Meia-Idade , Estudos Prospectivos , Espanha , Análise de Sobrevida , Resultado do TratamentoRESUMO
In this article, carbon fibres (CFs) are presented as sorbent material for the dispersive micro-solid phase extraction of twelve chlorophenols from urine samples. CFs are synthesized by a reagentless and green procedure consisting of heating raw cotton, a natural precursor, at high temperature (400°C) in an inert atmosphere (Ar) during 2h. The resulting fibres, which present good water dispersibility, are finally loaded on an in-syringe device. This device, which integrates the extraction and final elution of the analytes, is disposable and it is adapted to process low sample volumes. Working at the optimum conditions, the extraction procedure in combination with gas chromatography/mass spectrometry allows the determination of the analytes in urine at the low µg/L range. In fact, the limits of quantification (LOQs) of the analytes were in the interval from 1µg/L to 2.5µg/L with precision values, expressed as relative standard deviations (RSD), better than 13%. Relative recovery values, ranging from 74.5% to 113%, demonstrate the applicability of the proposed method.
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Clorofenóis/isolamento & purificação , Clorofenóis/urina , Cromatografia Gasosa-Espectrometria de Massas/métodos , Extração em Fase Sólida/métodos , Carbono/química , Fibra de Carbono , Humanos , Extração em Fase Sólida/instrumentação , SeringasRESUMO
AIMS: The aim of this study was to determine the antiviral activity of four probiotic metabolites (Lactobacillus and Bifidobacetrium species) against rotavirus in vitro infection monitored by the NSP4 protein production and Ca(2+) release. METHODS AND RESULTS: The antiviral effect of the metabolites was performed due a comparison between a blocking model and an intracelullar model on MA104 cells, with the response of NSP4 production and Ca(2+) liberation measured by flow cytometry. Significant results were obtained with the metabolites of Lactobacillus casei, and Bifidobacterium adolescentis in the reduction of the protein production (P = 0·04 and P = 0·014) and Ca(2+) liberation (P = 0·094 and P = 0·020) in the intracellular model, which suggests a successful antiviral activity against RV infection. CONCLUSIONS: This study demonstrates that probiotic metabolites were able to interfere with the final amount of intracellular NSP4 protein and a successful Ca(2+) regulation, which suggests a new approach to the mechanism exerted by probiotics against the rotavirus infection. SIGNIFICANCE AND IMPACT OF THE STUDY: A novel anti-rotaviral effect exerted by probiotic metabolites monitored by the NSP4 protein during the RV in vitro infection and the effect on the Ca(2+) release is reported; suggesting a reduction on the impact of the infection by decreasing the damage of the cells preventing the electrolyte loss.
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Antivirais/farmacologia , Bifidobacterium adolescentis/metabolismo , Glicoproteínas/metabolismo , Lacticaseibacillus casei/metabolismo , Probióticos/farmacologia , Rotavirus/efeitos dos fármacos , Toxinas Biológicas/metabolismo , Proteínas não Estruturais Virais/metabolismo , Animais , Antivirais/uso terapêutico , Linhagem Celular , Macaca mulatta , Probióticos/uso terapêutico , Rotavirus/metabolismo , Infecções por Rotavirus/tratamento farmacológico , Infecções por Rotavirus/virologiaRESUMO
There is controversy about the usefulness of bursectomy and omentectomy during the surgical treatment of gastric cancer. Bursectomy, a procedure dissecting the peritoneal lining covering the pancreas and the anterior plane of the transverse mesocolon, is a major surgical aggression. There is no evidence that the procedure improves five years survival. It may be useful in serosal gastric cancer of the posterior wall. Excision or resection of all or part of an omentum does not have either an effect on survival. However, we recommend its use since its lack of benefit has not been completely ascertained.
Dentro de las etapas quirúrgicas de la gastrectomía por cáncer gástrico, existen controversias respecto a la bursectomía y la omentectomía. La bursectomía (resección de peritoneo que cubre la porción anterior del mesocolon transverso y la cápsula pancreática) representa una mayor agresión quirúrgica, sin evidencia actual de que aumenta la sobrevida a 5 años, ello evaluado en 3 estudios clínicos. Su utilidad parece estar en pacientes con cáncer gástrico seroso de la cara posterior. La omentectomía total, comparada con la omentectomía parcial, ha sido evaluada más extensamente, sin poder demostrar hasta la actualidad la superioridad de uno u otro procedimiento en cuanto a sobrevida a 5 años. Sin embargo, mientras no se demuestre claramente lo opuesto en estudios científicos, recomendamos realizarla rutinariamente.
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Humanos , Gastrectomia/métodos , Neoplasias Gástricas/cirurgiaRESUMO
AIMS: To investigate the potential to degrade polycyclic aromatic hydrocarbons (PAHs) of yet-to-be-cultured bacterial populations from chronically polluted intertidal sediments. METHODS AND RESULTS: A gene variant encoding the alpha subunit of the catalytic component of an aromatic-ring-hydroxylating oxygenase (RHO) was abundant in intertidal sediments from chronically polluted subantarctic and temperate coastal environments, and its abundance increased after PAH amendment. Conversely, this marker gene was not detected in sediments from a nonimpacted site, even after a short-term PAH exposure. A metagenomic fragment carrying this gene variant was identified in a fosmid library of subantarctic sediments. This fragment contained five pairs of alpha and beta subunit genes and a lone alpha subunit gene of oxygenases, classified as belonging to three different RHO functional classes. In silico structural analysis suggested that two of these oxygenases contain large substrate-binding pockets, capable of accepting high molecular weight PAHs. CONCLUSIONS: The identified uncultured micro-organism presents the potential to degrade aromatic hydrocarbons with various chemical structures, and could represent an important member of the PAH-degrading community in these polluted coastal environments. SIGNIFICANCE AND IMPACT OF THE STUDY: This work provides valuable information for the design of environmental molecular diagnostic tools and for the biotechnological application of RHO enzymes.
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Bactérias/genética , Bactérias/isolamento & purificação , Metagenômica , Hidrocarbonetos Policíclicos Aromáticos/metabolismo , Água do Mar/microbiologia , Poluentes Químicos da Água/metabolismo , Bactérias/classificação , Bactérias/metabolismo , Biodegradação Ambiental , Hidrocarbonetos Aromáticos/metabolismo , Dados de Sequência Molecular , Filogenia , Água do Mar/análise , Poluição Química da ÁguaRESUMO
In this present study, magnetic Fe3O4@SiO2 nanoparticles (MNPs) functionalized with octadecyl groups (Fe3O4@SiO2-C18 NPs) were synthesized, characterized and employed, for the first time, as powerful nanosorbent to extract endogenous volatile organic metabolites (EVOMs) namely, hexanal, heptanal, decanal, benzaldehyde, 4-heptanone, 5-methyl-2-furfural and phenol, described as potential biomarkers of cancer, from human urine. By using co-precipitation, surface modification methods, the carbon-ferromagnetic nanocomposite was synthesized and characterized by infrared spectrum (IR) and transmission electron microscopy (TEM). By coupling with gas chromatography-mass spectrometry (GC-qMS), a reliable, sensitive and cost-effective method was validated. To test the extraction efficiency of the carbon-ferromagnetic nanocomposite toward urinary EVOMs experimental variables affecting the extraction performance, including nanosorbent amount, adsorption time, elution time, and nature of elution solvent, were investigated in detail. The extraction process was performed by dispersing Fe3O4@SiO2-C18 NPs into working solution containing targeted VOMs, and into urine samples, and then eluted with an adequate organic solvent. The eluate was collected, concentrated and analyzed by GC-qMS. Under the optimized conditions, the LODs and LOQs achieved were in the range of 9.7-57.3 and 32.4-190.9ng/mL, respectively. Calibration curves were linear (r(2)≥0. 988) over the concentration ranges from 0.25 to 250ng/mL. In addition, a satisfying reproducibility was achieved by evaluating the intra- and inter-day precisions with relative standard deviations (RSDs) less than 3 and 11%, respectively. The method also afforded satisfactory results in terms of the matrix effect (72.8-96.1%) and recoveries (accuracy) higher than 75.1% for most of the studied EVOMs. The Fe3O4@SiO2-C18 NPs-based sorbent extraction combined with GC-qMS revealed that the new nanosorbent had a strong ability to retain the target metabolites providing a new, reliable and high throughput strategy for isolation of targeted EVOMs in human urine, suggesting their potential to be applied in other EVOMs.
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Biomarcadores Tumorais/urina , Nanopartículas de Magnetita , Nanocompostos , Dióxido de Silício/química , Adsorção , Aldeídos/urina , Cromatografia Gasosa-Espectrometria de Massas , Humanos , Cetonas/urina , Limite de Detecção , Microscopia Eletrônica de Transmissão , Reprodutibilidade dos Testes , Extração em Fase Sólida/métodosRESUMO
In this article, the easy synthesis of magnetic nanoparticles-nylon 6 composite is presented, characterized and applied in the microextraction field. The one-step synthesis of the composite is performed by a solvent changeover playing with the different solubility of the polymeric network in formic acid and water. The new material has been characterized by different techniques including infrared spectroscopy, transmission and scanning microscopy. The extraction performance of the composite under a dispersive micro solid phase extraction format has been evaluated by determining four polycyclic aromatic hydrocarbons (benzo[b]fluoranthene, fluoranthene, indeno[1,2,3-cd]pyrene and phenanthrene) in water using ultra performance liquid chromatography (UPLC) combined with photo diode array detection. The developed methodology allows the determination of the analytes with limits of detection in the range from 0.05 µg/L (benzo[b]fluoranthene) to 0.58 µg/L (phenanthrene). The repeatability of the method was better than 6.9% at the limit of quantification level. The relative recoveries varied in the interval 80-111%.
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Caprolactama/análogos & derivados , Nanopartículas de Magnetita/química , Hidrocarbonetos Policíclicos Aromáticos/isolamento & purificação , Polímeros/química , Extração em Fase Sólida/métodos , Poluentes Químicos da Água/isolamento & purificação , Caprolactama/química , Cromatografia Líquida de Alta Pressão/métodos , Nanopartículas de Magnetita/ultraestrutura , Microscopia Eletrônica de Varredura , Microscopia Eletrônica de Transmissão , Hidrocarbonetos Policíclicos Aromáticos/química , Extração em Fase Sólida/instrumentação , Água/químicaRESUMO
In this article, carbon coated titanium dioxide nanotubes (c-TNTs) have been synthesized. The synthesis of the bare TNTs (b-TNTs) using anatase as precursor and their coating with a caramel layer have been performed by simple and cheap hydrothermal processes. The final conversion of the caramel layer in a carbon coating has been accomplished by a thermal treatment (600°C) in an inert (Ar) atmosphere. The c-TNTs have been characterized by different techniques including transmission microscopy, infrared spectroscopy, X-ray powder diffraction, thermogravimetry and Brunauer, Emmett and Teller (BET) adsorption isotherms. The extraction performance of the c-TNTs under a microextraction format has been evaluated and compared with that provided by b-TNTs and multiwalled carbon nanotubes (MWCNTs) using naproxen and ketoprofen as model analytes. c-TNTs provided better results than the other nanoparticles, especially at low acidic pH values. In addition, c-TNTs presented a better dispersibility than MWCNTs, which is very interesting for their use in dispersive micro-solid phase extraction. Finally, a microextraction format, adapted to low sample volumes, has been proposed and applied for the determination of naproxen and ketoprofen in saliva and urine samples by liquid chromatography with UV detection. The results indicate that this approach is promising for the analysis of biological samples. In fact, the recoveries were in the range between 96% and 119% while the precision, expressed as relative standard deviation, was better than 8.5% and 26.3% for urine and saliva, respectively. The detection limits were in the range 34.1-40.8µg/L for saliva samples and 81.1-110µg/L for urine samples.
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Carbono/química , Nanotubos de Carbono/química , Extração em Fase Sólida/métodos , Titânio/química , Adsorção , Concentração de Íons de Hidrogênio , Microscopia Eletrônica de Transmissão , Nanopartículas/química , Nanotubos de Carbono/ultraestrutura , Espectroscopia de Infravermelho com Transformada de Fourier , TermogravimetriaRESUMO
In the present article, a novel extraction/stirring approach in the liquid phase microextraction context is presented. The new technique is based on octadecyl coated borosilicate disks which act as support of the organic extracting solvent thanks to hydrophobic interactions. The disk is integrated in a stirring element which favors the transference of the analytes to the extraction phase. The proposed extraction procedure has been characterized using the determination of nine herbicides in water samples by ultra performance liquid chromatography (UPLC) combined with ultraviolet (UV) detection as model analytical problem. All the variables involved in the extraction have been studied and optimized in depth and the optimized technique provides enrichment factors in the range from 79 to 839. The method has been analytically characterized on the basis of its linearity, sensitivity and precision. Limits of detection were in the range from 0.14µg/L (atrazine) to 0.56µg/L (terbumeton) with precision better than 7.3% (expressed as relative standard deviation). Relative recoveries were close to 100%, which demonstrated the applicability of the stir octadecyl-modified borosilicate disk for the proposed analytical problem.