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1.
J Chromatogr A ; 1638: 461887, 2021 Feb 08.
Artigo em Inglês | MEDLINE | ID: mdl-33477026

RESUMO

In the presented work, MIL-101(Cr) and chitosan were directly embedded on the skeleton of melamine sponge material using a simple and environmentally friendly method. Chitosan acts not only as an adhesive during the preparation of functionalized sponges, but also as an adsorption adjuvant in herbicide detection. Unlike other polymers, chitosan has excellent hydrophilicity and contains numerous adsorption sites; thus, it enables the sponge material to be used for determination of contaminants in an aqueous phase. Scanning electron microscopic (SEM) analysis showed that the coating material was uniformly distributed on the skeleton of melamine sponge. The prepared material was used as a sorbent in a vortex-assisted solid-phase extraction and combined with high performance liquid phase tandem mass spectrometry for the extraction and trace determination of six triazines in water samples (Atraton, Desmetryn, Prometon, Ametryn, Prometryn and Dimethametryn). Several parameters that affect the extraction efficiencies were investigated. Under the optimal conditions (MIL-101(Cr) loading, 150 mg; sample pH, 7; salt concentration, 0%; adsorption time, 3 min; desorption solvent, 1.5 mL acetonitrile; desorption time, 4 min), the proposed method was successfully used in the determination of trace triazines in five real water samples (drinking water, tap water, lake waters and river water), satisfactory recoveries were obtained in the range of 78.9%-118.6%. The limits of detection of the proposed method in detecting triazine herbicides in spiked water samples ranged from 0.014 to 0.045 ng mL-1.


Assuntos
Herbicidas/análise , Interações Hidrofóbicas e Hidrofílicas , Estruturas Metalorgânicas/química , Extração em Fase Sólida/métodos , Espectrometria de Massas em Tandem/métodos , Triazinas/análise , Poluentes Químicos da Água/análise , Adsorção , Cromatografia Líquida de Alta Pressão/métodos , Cromatografia Líquida , Concentração de Íons de Hidrogênio , Reprodutibilidade dos Testes , Sais/química , Solventes/química , Fatores de Tempo , Triazinas/química
2.
Food Chem ; 339: 127844, 2021 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-32829243

RESUMO

Fat-filled milk powders (FMP) are inexpensive milk alternatives predominantly exported to developing countries to satisfy growing demands for dairy proteins. Harsh climatic and sanitary conditions, poor border controls and relatively long periods for distribution and storage enhance the inherent vulnerability of FMP to fraud and stability. Rapid, low-cost methods are needed for extensive routine authentication of FMP products. This study investigated, for the first time, the sample integrity and the quality dynamics of 7 Nigerian FMP brands stored for 7 weeks at 40 °C. The prominent melamine and urea absorption peaks were absent, but protein contents were below the permitted limit. The peak absorbance of the OH functional group increased while the tryptophan contents decreased with storage time. Multiclass analyses differentiated the fresh FMP brands from one another, and from those that were aged. Robust interval-PLS predictions obtained for storage time may be excellent indicators of FMP freshness and stability.


Assuntos
Embalagem de Alimentos/métodos , Leite/química , Animais , Cromatografia Gasosa , Cromatografia Líquida de Alta Pressão , Ácidos Graxos/análise , Microbiologia de Alimentos , Análise dos Mínimos Quadrados , Leite/microbiologia , Nigéria , Pós/química , Análise de Componente Principal , Salmonella/isolamento & purificação , Temperatura , Triazinas/análise , Ureia/análise
3.
Food Chem ; 338: 127769, 2021 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-32862067

RESUMO

Illegal addition of melamine (MEL) to milk has caused serious food safety accident. It is urgent to develop a highly sensitive method for detecting MEL in milk. ß-Cyclodextrin with inner hydrophobic and outer hydrophilic cavities have been widely used in smart sensors design. In this study, an "ON-OFF-ON" sensor for MEL detection was constructed based on ß-cyclodextrin modified carbon nanoparticles (ß-CD-CNPs). The sensor is switched "OFF" when Fe3+ interacts with ß-CD-CNPs and switched "ON" when MEL replaces Fe3+. Fluorescence recovery of ß-CD-CNPs exhibits good linear correlations with MEL concentration ranging from 10.00 ng/mL ~ 180.00 ng/mL and 180.00 ~ 1000.00 ng/mL, the detection limit is 6.82 ng/mL. The sensor was applied to analysis melamine in milk samples with recovery between 94.80% ~ 102.05%, and RSD bellow 12.61%. The results show that this method can meet the requirements of real sample analysis.


Assuntos
Carbono/química , Análise de Alimentos/métodos , Leite/química , Nanopartículas/química , Triazinas/análise , Triazinas/química , beta-Ciclodextrinas/química , Animais , Contaminação de Alimentos/análise , Limite de Detecção , Espectrometria de Fluorescência
4.
Mar Pollut Bull ; 158: 111402, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32753187

RESUMO

Antifouling biocides are known to leach out of paints and into the aquatic environment. There is currently a data gap on the occurrence of the current antifouling biocides, as legislative changes caused a change in the antifouling market. Therefore, a comprehensive monitoring study was performed across 13 Danish marinas, both waters and sediments were analyzed, including a transect and a study with seasonal resolution. Three biocides, i.e., Medetomidine, Tralopyril, and DCOIT were not detected in any of the samples. More commonly found, in 11 of the 13 marinas, were the hydrolysis products of Dichlofluanid (DMSA) and Tolylfluanid (DMST). These biocides rapidly dropped in concentration and reached background levels around 200 m from the source. The antifouling biocide Irgarol 1051 was found in all sediment samples and half of all water samples. The concentrations of Irgarol were lower than previously monitored. The decrease can likely be attributed to legislative changes and its disapproval for use since 2016.


Assuntos
Desinfetantes/análise , Poluentes Químicos da Água/análise , Dinamarca , Monitoramento Ambiental , Pintura , Triazinas/análise
5.
Environ Res ; 188: 109836, 2020 09.
Artigo em Inglês | MEDLINE | ID: mdl-32798953

RESUMO

The ability of calcium peroxide (CaO2) to degrade hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) in contaminated soil slurries using CaO2-based modified Fenton oxidation was investigated. Results showed that increasing the CaO2 dose increased degradation rates of RDX and pH. RDX concentrations decreased to below detection after 18 h with 2 M and 2.5 M CaO2, after 30 h with 1.5 M CaO2, after 54 h with 1 M CaO2, but 0.1 M CaO2 achieved no significant RDX removal. Increasing the soil organic matter content decreased the rate and extent of RDX degradation. RDX degradation products 4-nitro-2,4-diazabutanal (NDAB) and methylenedinitramine (MEDINA) were quantified, and the greater accumulation of NDAB than MEDINA suggests denitration of RDX was the most likely initial degradation step. Isotopic ratios for nitrogen and oxygen associated with RDX oxidation are also consistent with either nitrification of NH4+ from soil or precipitation. Existing technologies merely only extract energetics from soils for treatment ex situ, whereas the approach introduced herein destroys RDX in situ with a one-step application.


Assuntos
Esgotos , Triazinas , Biodegradação Ambiental , Peróxidos , Solo , Triazinas/análise
6.
J Chromatogr A ; 1627: 461398, 2020 Sep 13.
Artigo em Inglês | MEDLINE | ID: mdl-32823103

RESUMO

A new mode of dispersive solid phase extraction based on in situ formation of adsorbent in aqueous phase has been introduced as an efficient method for the extraction of some pesticide residues in fruit juice samples. In this method, polycarbonate which is an inexpensive polymer is used as an adsorbent for the first time. The method is followed by dispersive liquid-liquid microextraction for more enrichment of the analytes. In the present study, a proper amount of the polymer is dissolved in N,N-dimethyl formamide and the obtained solution is injected into an aqueous phase containing the analytes. After injection, polycarbonate particles are formed and adsorbed the analytes. Then, the adsorbent is separated from the aqueous solution and eluted by acetone. The obtained acetone phase is mixed with 1,1,1-trichloroethane and the mixture is dispersed into deionized water and a cloudy solution is formed. Ultimately, after centrifugation, the obtained sedimented phase containing the extracted analytes is injected into gas chromatography-flame ionization detection. In the proposed method, the adsorbent synthesis step, which often is a time-consuming, expensive, and laborious step in most adsorbent-based sample preparation methods, has been removed. Moreover, there is no need for sonication or vortex agitation. Under the optimized experimental conditions, the relative standard deviation was equal or less than 7% for intra- (n = 6) and inter-day (n = 5) precisions at a concentration of 50 µg L-1 of each pesticide. The limits of detection and quantification were in the ranges of 0.34-1.2 and 1.1-4.0 µg L-1, respectively. In addition, extraction recoveries and enrichment factors varied in the ranges of 44-89% and 220-443, respectively.


Assuntos
Sucos de Frutas e Vegetais/análise , Cromatografia Gasosa-Espectrometria de Massas/métodos , Resíduos de Praguicidas/análise , Centrifugação , Limite de Detecção , Microextração em Fase Líquida/métodos , Resíduos de Praguicidas/isolamento & purificação , Extração em Fase Sólida , Solventes/química , Triazinas/análise , Triazinas/isolamento & purificação , Água/química
7.
J Environ Sci Health B ; 55(10): 865-875, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32657214

RESUMO

This research aimed at implementing and validating a method for analysis of pesticide residues in crops. QuEChERS extraction method with PSA purification was used following analyzes by gas chromatography with tandem mass spectrometry in Selected Reaction Monitoring mode. A short run method was successfully developed for the determination of 41 pesticides, confirmed by two precursor-products for each analyte. The calibration curve for each analyte was linear at concentration range from 1 to 500 µg kg-1 with correlation coefficients higher than 0.99, low limits of detection (0.03 - 10.22 µg kg-1) and satisfactory precision. The developed method was used to investigate apples; mangos; strawberries; cucumbers and tomatoes from the Rio de Janeiro Food Distribution Center (CEASA).Most of the targeted pesticides (78%) were below detection limits. Apple and strawberry presented the highest pesticide contamination levels, many of which are not authorized by tthe Brazilian national regulatory agency (ANVISA).


Assuntos
Produtos Agrícolas/química , Cromatografia Gasosa-Espectrometria de Massas/métodos , Resíduos de Praguicidas/análise , Piretrinas/análise , Extração em Fase Sólida/métodos , Espectrometria de Massas em Tandem/métodos , Triazinas/análise , Brasil , Cucumis sativus/química , Contaminação de Alimentos/análise , Fragaria/química , Lycopersicon esculentum/química , Malus/química , Mangifera/química
8.
Nature ; 586(7827): 113-119, 2020 10.
Artigo em Inglês | MEDLINE | ID: mdl-32707573

RESUMO

The emergence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in 2019 has triggered an ongoing global pandemic of the severe pneumonia-like disease coronavirus disease 2019 (COVID-19)1. The development of a vaccine is likely to take at least 12-18 months, and the typical timeline for approval of a new antiviral therapeutic agent can exceed 10 years. Thus, repurposing of known drugs could substantially accelerate the deployment of new therapies for COVID-19. Here we profiled a library of drugs encompassing approximately 12,000 clinical-stage or Food and Drug Administration (FDA)-approved small molecules to identify candidate therapeutic drugs for COVID-19. We report the identification of 100 molecules that inhibit viral replication of SARS-CoV-2, including 21 drugs that exhibit dose-response relationships. Of these, thirteen were found to harbour effective concentrations commensurate with probable achievable therapeutic doses in patients, including the PIKfyve kinase inhibitor apilimod2-4 and the cysteine protease inhibitors MDL-28170, Z LVG CHN2, VBY-825 and ONO 5334. Notably, MDL-28170, ONO 5334 and apilimod were found to antagonize viral replication in human pneumocyte-like cells derived from induced pluripotent stem cells, and apilimod also demonstrated antiviral efficacy in a primary human lung explant model. Since most of the molecules identified in this study have already advanced into the clinic, their known pharmacological and human safety profiles will enable accelerated preclinical and clinical evaluation of these drugs for the treatment of COVID-19.


Assuntos
Antivirais/análise , Antivirais/farmacologia , Betacoronavirus/efeitos dos fármacos , Infecções por Coronavirus/tratamento farmacológico , Infecções por Coronavirus/virologia , Avaliação Pré-Clínica de Medicamentos , Reposicionamento de Medicamentos , Pneumonia Viral/tratamento farmacológico , Pneumonia Viral/virologia , Monofosfato de Adenosina/análogos & derivados , Monofosfato de Adenosina/farmacologia , Alanina/análogos & derivados , Alanina/farmacologia , Células Epiteliais Alveolares/citologia , Células Epiteliais Alveolares/efeitos dos fármacos , Betacoronavirus/crescimento & desenvolvimento , Linhagem Celular , Inibidores de Cisteína Proteinase/análise , Inibidores de Cisteína Proteinase/farmacologia , Relação Dose-Resposta a Droga , Sinergismo Farmacológico , Regulação da Expressão Gênica/efeitos dos fármacos , Humanos , Hidrazonas , Células-Tronco Pluripotentes Induzidas/citologia , Modelos Biológicos , Morfolinas/análise , Morfolinas/farmacologia , Pandemias , Pirimidinas , Reprodutibilidade dos Testes , Bibliotecas de Moléculas Pequenas/análise , Bibliotecas de Moléculas Pequenas/farmacologia , Triazinas/análise , Triazinas/farmacologia , Internalização do Vírus/efeitos dos fármacos , Replicação Viral/efeitos dos fármacos
9.
Bull Environ Contam Toxicol ; 105(2): 332-336, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32556692

RESUMO

Since the Directive 2013/39/EU included terbutryn to the list of priority substances of all water bodies, a previous method based on dispersive liquid-liquid micro-extraction (DLLME) for the determination of triazines in seawater has been modified. The main change consisted on the use of tandem mass spectrometry instead of diode array as detection technique. Due to the higher sensitivity of mass detector, sample volume was reduced and extraction solvent volume was optimized. The optimum extraction conditions were 5 mL of sample, 50 µL of 1-octanol and an agitation step instead of disperser solvent. The obtained analytical recoveries (73%-101% with relative standard deviations below 4%) meeting the requirements. The limits of quantification (between 0.016 and 0.021 µg L-1) were more than 10 times lower than the limit set by the European Directive 2013/39/EU for terbutryn (0.34 µg L-1). The proposed method was applied to the determination of the target compounds in seawater samples from A Coruña (Galicia, NW of Spain).


Assuntos
Espectrometria de Massas em Tandem/métodos , Triazinas/análise , Poluentes Químicos da Água/análise , Microextração em Fase Líquida/métodos , Água do Mar/química , Solventes/química , Espanha
10.
J Environ Sci Health B ; 55(9): 783-793, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32586197

RESUMO

Considering the increase in agricultural production in Tocantins and in the use of pesticides for such production, this work investigates the levels of pesticide residues in different environmental compartments (soil, sediment, and water samples) of the Formoso River in the state of Tocantins, Brazil. The presence of pesticides of the triazine, triazole, and benzimidazole classes was analyzed by UHPLC-MS/MS from April 2018 to February 2019. There were four quarterly collections in the dry and rainy periods. The active principles were not found in sediment samples. In soil samples, only the active ingredients tebuconazole and propiconazole were found in the third collection campaign. The active ingredients amethryn, atrazine, carbendazim, epoxiconazole, metconazole, propiconazole, simazine, tebuconazole, and tetraconazole were found in water samples from Formoso River at concentrations of up to 0.286 µg L-1 (atrazine). Although the substances are in low concentrations, we cannot assume that this toxicity is low considering that the risk of a certain pesticide depends on levels and exposure time. Therefore, the action of substances external to the natural environment always threatens biodiversity.


Assuntos
Benzimidazóis/análise , Praguicidas/análise , Triazinas/análise , Triazóis/análise , Poluentes Químicos da Água/análise , Brasil , Cromatografia Líquida de Alta Pressão , Monitoramento Ambiental , Sedimentos Geológicos/análise , Resíduos de Praguicidas/análise , Rios/química , Poluentes do Solo/análise , Espectrometria de Massas em Tandem
11.
Artigo em Inglês | MEDLINE | ID: mdl-32397178

RESUMO

Terbuthylazine is commonly used as an herbicide to control weeds and prevent non-desirable grow of algae, fungi and bacteria in many agricultural applications. Despite its highly negative effects on human health, environmental modeling of this kind of pesticide in the vadose zone till reaching groundwater is still not being done on a regular basis. This work shows results obtained by two mathematical models (PESTAN and PRZM-GW) to explain terbuthylazine behavior in the non-saturated zone of a vertical soil column. One of the models use a one-dimensional analytical formulation to simulate the movement of terbuthylazine through the non-saturated soil to the phreatic surface. The second and more complex model uses a whole set of parameters to solve a modified version of the mass transport equation considering the combined effect of advection, dispersion and reactive transport processes. Both models have been applied as a case-study on a particular location in South Valencia Aquifer (Spain). A whole set of simulation scenarios have been designed to perform a parameter sensitivity analysis. Despite both models leading to terbuthylazine's concentration values, numerical simulations show that PRZM-GW is able to reproduce concentration observations leading to much more accurately results than those obtained using PESTAN.


Assuntos
Água Subterrânea/análise , Triazinas/análise , Poluentes Químicos da Água , Modelos Teóricos , Solo , Espanha , Poluentes Químicos da Água/análise
12.
Food Chem ; 326: 126988, 2020 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-32447162

RESUMO

In this study, a simple and quick ionic liquid- based ultrasonic-assisted microextraction (IL-UA-ME) procedure has been improved for extraction of melamine in dairy productsfollowed by UV-VIS spectrometry. For the analysis of stability and reactivity of melamine and its some metal complexes, quantum chemical parameters like frontier orbital energy-HOMO-LUMO energy gap, hardness and softness were calculated using computational chemistry tools. The results regarding to stability analysis made considering density functional theory showed that theoretical data obtained are compatible with experimentally obtained results, and Fe-melamine complex is more stable compared to others. Under optimum conditions, the linearity was in the range of 0.05-400 ng mL-1 with detection limit of 0.015 ng mL-1. Following the validation studies, recovery and relative standard deviation were obtained in range of 92.5-104.3% and 1.4-2.1%, respectively. The first research article in which experimental and theoretical studies are used together for the determination of melamine in dairy products.


Assuntos
Laticínios/análise , Líquidos Iônicos/química , Triazinas/análise , Complexos de Coordenação/química , Concentração de Íons de Hidrogênio , Limite de Detecção , Teoria Quântica , Microextração em Fase Sólida , Sonicação , Temperatura , Triazinas/química , Triazinas/isolamento & purificação
13.
Chemosphere ; 252: 126533, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32217410

RESUMO

Despite frequent detection of atrazine (ATZ) and its degradates (including hydroxyatrazine, ATZ-OH; deethylatrazine, DEA; deisopropylatrazine, DIA; and deethyldeisopropylatrazine, DACT) in a variety of water bodies, documentation of their occurrence and distribution in tap water in China is still scarce. A nationwide survey about ATZ and its degradates (ATZs) in tap water from 31 provinces in 7 regions of mainland China and Hong Kong was conducted during June 2019. At least one of the analytes was found in all the water samples (n = 884). The median sum concentrations of ATZs (ΣATZs) was 21.0 ng/L (range: 0.02 ng/L-3.04 µg/L). The predominant compounds of ATZs in tap water were ATZ and DEA, with a detection frequency of 99.5% and 98.0%, respectively, followed by ATZ-OH (87.3%), DACT (84.0%), and DIA (78.1%). Significant regional variations (p < 0.05) were found in the concentrations of ATZs in tap water, and the highest concentration of ΣATZs (median: 254 ng/L, range: 0.44 ng/L-3.04 µg/L) was found in Northeastern China, followed by Eastern (37.2 ng/L, 0.02-706 ng/L), Northern (30.2 ng/L, 0.04-317 ng/L), Central (29.3 ng/L, 0.04-256 ng/L), Southern (25.0 ng/L, 0.04-297 ng/L), Southwestern (17.2 ng/L, 0.02-388 ng/L), and Northwestern China (3.22 ng/L, 0.06-214 ng/L). The level of ΣATZs in groundwater from rural area of China was about 1/3 of that found in tap water. ATZs cannot be removed by boiling tap water. The highest estimated daily intake of ΣATZs (248 ng/kg-body weight/day) was found in the infant population of Changchun, Jilin, Northeastern China.


Assuntos
Atrazina/análise , Exposição Ambiental/análise , Poluentes Químicos da Água/análise , Poluição Química da Água/estatística & dados numéricos , Atrazina/análogos & derivados , China , Exposição Ambiental/estatística & dados numéricos , Água Subterrânea , Herbicidas/análise , Hong Kong , Humanos , Triazinas/análise , Água
14.
Ecotoxicol Environ Saf ; 194: 110363, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-32120175

RESUMO

Triafamone is a highly effective, low toxicity sulfonamide herbicide widely used for weeding paddy fields. The triafamone photodegradation in water environment must be explored for its ecological risk assessment. In this work, the effects of chemical fertilizer (urea, diammonium phosphate, potassium chloride, and potassium sulfate), urea metabolites (CO32- and HCO3-), and organic fertilizers (unfermented organic fertilizer [UOF] and fermented organic fertilizer [FOF]) on the triafamone photodegradation in aqueous solution under simulated sunlight were evaluated. Results showed that the triafamone photodegradation rate was unaffected by urea. The half-life of triafamone decreased from 106.8 h to 68.4 h with increasing diammonium phosphate concentration. Potassium chloride, potassium sulfate, CO32-, and HCO3- could accelerate the triafamone photodegradation at all concentrations, whereas the degradation rate of triafamone decreased when the concentration of potassium sulfate or CO32- was 2000 mg/L. Triafamone photodegradation was promoted by 20-200 mg/L UOF and FOF but decreased to 236.6 and 142.3 h when the concentration reached 2000 mg/L. Twenty-three transformation products were isolated and identified from triafamone by using ultra-performance liquid chromatography with quadrupole time-of-flight mass spectrometry under simulated sunlight irradiation, and the kinetic evolution of these products was explored. Five possible degradation pathways were inferred, including the cleavage of C-N, C-C, and C-O bonds; CO bond hydrogenation; the cleavage of triazine ring; the cleavage of the sulfonamide bridge; hydroxylation; hydroxyl substitution; methylation; demethylation; amination; and rearrangement. In summary, these results are important for elucidating the environmental fate of triafamone in aquatic systems and further assessing environmental risks.


Assuntos
Anilidas/toxicidade , Herbicidas/toxicidade , Triazinas/toxicidade , Poluentes Químicos da Água/toxicidade , Cromatografia Líquida , Cinética , Espectrometria de Massas , Fotólise , Sulfonamidas/análise , Luz Solar , Triazinas/análise , Água/química , Poluentes Químicos da Água/análise
15.
Chemosphere ; 244: 125505, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-32050329

RESUMO

Melamine (MEL) and its derivatives are widely used in many consumer products, including furniture, kitchenware, and plastics. However, very limited knowledge exists on human exposure to MEL and its derivatives, especially in the indoor environment. Here, we determined the occurrence and distribution of 11 MEL derivatives in childcare facilities and estimated children's exposure through dust ingestion and dermal absorption. We analyzed dust and samples of nap mats, a commonly used item in many childcares, from eight facilities located in the United States. Eight MEL-based compounds were detected in dust, and total MEL concentrations ranged from 429 to 117,000 ng/g. The most abundant compounds found in the dust samples were MEL, cyanuric acid (CYA), ammeline (AMN), and ammelide (AMD), with median concentrations of 1620, 585, 1060, and 299 ng/g, respectively. MEL, CYA, AMN and 2,4,6-tris[bis(methoxymethyl)amino]-1,3,5-triazine (TBMMAT) were also detected in nap mats with median concentrations of 45.6, 19.8, 1510 and 2.5 ng/g, respectively. ΣMEL concentrations in mat covers (median 709 ng/g) were significantly higher than those in mat foam (median 15.1 ng/g). Estimated daily intakes (EDIs) of MEL and its derivatives via dust ingestion were two orders of magnitude higher than the EDIs through dermal absorption, but both were below the established tolerable daily intake levels. This is the first report on exposure to MEL and its derivatives in the childcare environment.


Assuntos
Creches/normas , Exposição Ambiental/análise , Triazinas/farmacologia , Poluição do Ar em Ambientes Fechados/análise , Criança , Poeira/análise , Humanos , Absorção Cutânea , Triazinas/análise , Estados Unidos
16.
Nanoscale ; 12(7): 4562-4572, 2020 Feb 21.
Artigo em Inglês | MEDLINE | ID: mdl-32043096

RESUMO

The ratiometric fluorescence technique is of great interest due to its visualization characteristics. The construction of a reliable fluorescent ratiometric nanoprobe for high-sensitivity visual quantification is highly sought after but it is limited by poor stability and controllability. Herein, we report a robust dual-emissive quantum dot nanohybrid with precise color tunability and demonstrate its potential as a two-signal-change ratiometric probe for visual detection. A novel assembly strategy was developed for spatially implanting hydrophobic green and red quantum dots (QDs) into a silica scaffold to form a dual-emissive hierarchical fluorescent silica nanohybrid. The fluorescence intensity ratio and color of the nanohybrid were precisely tailored by altering the amounts of green and red QDs. Particularly, after the alkylsilane-mediated phase transfer and exterior silica shell growth, the nanohybrid exhibited the well-preserved fluorescence features of the original QDs and robust optical/colloid stability. An inner filter-based ratiometric nanoprobe for the visual determination of melamine was ultimately devised by combining the spectra-overlapped two-colored fluorescent nanohybrid with analyte-specific gold nanoparticles. Furthermore, based on the reversible fluorescence signal changes in two-colored QDs induced by melamine, a logic gate strategy for melamine monitoring was constructed. The newly developed fluorescent ratiometric nanoprobe shows great prospects for the visual and quantitative determination of analytes in a complex biological matrix.


Assuntos
Ouro/química , Nanopartículas Metálicas/química , Pontos Quânticos/química , Triazinas/análise , Limite de Detecção , Dióxido de Silício/química
17.
Chemosphere ; 250: 126210, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32109698

RESUMO

This study utilized innovative analyses to develop multiple lines of evidence for natural attenuation of hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) in groundwater at the U.S. Department of Energy's Pantex Plant. RDX, as well as the degradation product 4-nitro-2,4-diazabutanal (NDAB; produced by aerobic biodegradation or alkaline hydrolysis) were detected in a large portion of the plume, with lower concentrations of the nitroso-containing metabolites produced during anaerobic biodegradation. 16S metagenomic sequencing detected the presence of bacteria known to aerobically degrade RDX (e.g., Gordonia, Rhodococcus) and NDAB (Methylobacterium), as well as the known anoxic RDX degrader Pseudomonas fluorescens I-C. Proteomic analysis detected both the aerobic RDX degradative enzyme XplA, and the anoxic RDX degradative enzyme XenB. Groundwater enrichment cultures supplied with low concentrations of labile carbon confirmed the potential of the extant groundwater community to aerobically degrade RDX and produce NDAB. Compound-specific isotope analysis (CSIA) of RDX collected at the site showed fractionation of nitrogen isotopes with δ15N values ranging from approximately -5‰ to +9‰, providing additional evidence of RDX degradation. Taken together, these results provide evidence of in situ RDX degradation in the Pantex Plant groundwater. Furthermore, they demonstrate the benefit of multiple lines of evidence in supporting natural attenuation assessments, especially with the application of innovative isotopic and -omic technologies.


Assuntos
Biodegradação Ambiental , Água Subterrânea/química , Triazinas/metabolismo , Poluentes Químicos da Água/metabolismo , Substâncias Explosivas/análise , Gordonia (Bactéria)/metabolismo , Água Subterrânea/microbiologia , Isótopos de Nitrogênio/análise , Proteômica , Rhodococcus/metabolismo , Triazinas/análise , Poluentes Químicos da Água/análise
18.
Talanta ; 211: 120705, 2020 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-32070571

RESUMO

Barium sulfate-coated CsPbBr3 perovskite nanocrystals (CsPbBr3 NCs@BaSO4) was successfully synthesized that exhibited stable and intense fluorescence property in aqueous buffer. With the CsPbBr3 NCs@BaSO4 as signal readout, an ultrasensitive fluorescence nanosensor was developed for turn-on determination of melamine by the manipulation of inner filter effect of citrate-protected gold nanoparticles (AuNPs). The fluorescence of the CsPbBr3 NCs@BaSO4 was remarkably quenched by the AuNPs due to inner filter effect. This inner filter effect could be weakened by the addition of melamine as a result of melamine-triggering aggregation of the AuNPs and subsequently led to a recovery in the fluorescence of the CsPbBr3 NCs@BaSO4. The recovery ratio was proportional to the concentration of melamine in the range of 5.0-500.0 nmol/L. The limit of detection was 0.42 nmol/L and the relative standard deviation was 4.0% for the repetitive determination of 500.0 nmol/L melamine solution (n = 11). The nanosensor was successfully applied to analysis of melamine in dairy product samples.


Assuntos
Compostos de Cálcio/química , Laticínios/análise , Contaminação de Alimentos/análise , Ouro/química , Nanopartículas/química , Óxidos/química , Titânio/química , Triazinas/análise , Animais , Sulfato de Bário/química , Ácido Cítrico/química , Fluorescência , Limite de Detecção , Triazinas/química
19.
Hum Exp Toxicol ; 39(5): 624-633, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-31928232

RESUMO

Melamine contamination is a recent public health problem emerging globally. Present study aimed to detect the rate of melamine presence in human milk in a cohort study and to evaluate any possible differences in maternal-infant pair characteristics such as breastfeeding status, crying and sleep problems of infants, maternal postpartum depression, maternal-infant bonding, infant and maternal anthropometry, and maternal complete blood count caused by the melamine exposure. Mothers of infants born in Sanliurfa were invited to participate in 'Urfa Child Cohort Survey'. Overall, two breast milk samples were taken between 5 days and 15 days postpartum and between 4 weeks and 10 weeks. Randox Food's InfiniPlex array was used to analyse the presence of melamine. Melamine was detected in 32.2% and 24.4% of the first and the second milk samples; 16.7% of mothers had two positive samples. z Scores for birth weight and z scores for height for age were detected to be significantly lower in cases with two positive samples compared to cases with negative samples. Mean maternal white blood cells counts were found to be lower in cases with repeated melamine contact. Melamine might have a detrimental effect on birth weight, infant height and maternal blood count. Further studies should be done to detect environmental contamination in different regions and countries.


Assuntos
Peso ao Nascer/efeitos dos fármacos , Estatura/efeitos dos fármacos , Poluentes Ambientais , Contagem de Leucócitos , Leite Humano/química , Triazinas , Adulto , Estudos de Coortes , Poluentes Ambientais/análise , Poluentes Ambientais/toxicidade , Feminino , Humanos , Recém-Nascido , Masculino , Exposição Materna/efeitos adversos , Mães , Triazinas/análise , Triazinas/toxicidade
20.
J Sep Sci ; 43(6): 1107-1118, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31917521

RESUMO

This work provides a simple and rapid method for synthesis uniform simetryn imprinted nanoparticles, which can be used to pretreat the tested samples before detecting. A series of computational approach were employed for design simetryn-imprinted polymer. Based on the conclusion of theoretical calculation, the simetryn imprinted nanoparticles were synthesized using simetryn as template, methacrylic acid as monomer with different solvent volume and synthesis conditions. The obtained nanoparticles have small size, uniform distribution and high imprinted factor. Scatchard analysis and quantum chemical calculations were applied for evaluating the interaction of simetryn with methacrylic acid in the imprinting process. The selectivity and recognition ability of the simetryn imprinted nanoparticles for six triazine herbicides and two other type herbicides were investigated. The results show that the simetryn imprinted nanoparticles had high selectivity and binding capacity and could be used for the separation and enrichment of four triazine pesticide residues from actual samples. A method of molecularly imprinted matrix solid phase extraction ultra-performance liquid chromatography tandem mass spectrometry was established for detecting four kinds of triazine herbicide residues in tobacco. The recovery rate of terbuthylazine, simetryn, atrazine, and prometryn in tobacco was 84.03-119.05%, and the relative standard deviation was 0.35-10.12%.


Assuntos
Impressão Molecular , Nanopartículas/química , Resíduos de Praguicidas/análise , Triazinas/análise , Cromatografia Líquida de Alta Pressão , Teoria da Densidade Funcional , Espectrometria de Massas em Tandem , Triazinas/síntese química , Triazinas/química
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