Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 31
Filtrar
1.
J AOAC Int ; 107(4): 632-640, 2024 Jul 04.
Artigo em Inglês | MEDLINE | ID: mdl-38565261

RESUMO

BACKGROUND: An interlaboratory study was conducted at the U.S. Food and Drug Administration's (FDA) Northeast Food and Feed Laboratory (NFFL) and the Center for Food Safety and Applied Nutrition (CFSAN) with the purpose to expand FDA Elemental Analysis Manual (EAM) method 4.7 (Inductively Coupled Plasma-Mass Spectrometric Determination of Arsenic, Cadmium, Chromium, Lead, Mercury, and Other Elements in Food Using Microwave Assisted Digestion) to include new analytes. OBJECTIVE: The goal of the study was to demonstrate the performance of FDA EAM method 4.7 when analyzing new analytes cobalt (Co), strontium (Sr), thallium (Tl), tin (Sn), uranium (U), and vanadium (V). This analyte extension method validation of EAM 4.7 for six additional elements, Co, Sr, Tl, Sn, U, and V, followed all guidelines for a Level 2 or single-laboratory validation and met all acceptance criteria for analyte extensions as per the Guidelines for the Validation of Chemical Methods. METHOD: As per EAM 4.7, this study followed the procedures and used specified equipment operated under recommended conditions. The analyte extension method validation was performed in accordance with protocol and with no deviations. RESULTS: All quality control (QC) requirements for this analyte extension method validation of EAM 4.7 passed as evidenced by the analytical data. The results presented demonstrate accuracy, linearity, and precision by successful analyses of method blanks, matrix spikes, unfortified test samples, and reference materials. The data analyzed met each of the validation requirements for each analyte in all representative matrixes. CONCLUSIONS: The study showed that the new analytes performed satisfactorily using EAM 4.7 for total acidic extractable elemental analysis of food according to FDA's guidelines. HIGHLIGHTS: The method met or exceeded the performance criteria.


Assuntos
Cobalto , Estrôncio , Tálio , Estanho , Urânio , Cobalto/análise , Tálio/análise , Urânio/análise , Estanho/análise , Estrôncio/análise , Vanádio/análise , Análise de Alimentos/métodos , Espectrometria de Massas/métodos , Estados Unidos , United States Food and Drug Administration
2.
PLoS One ; 18(11): e0293334, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-37943816

RESUMO

Mesoscale oceanographic features, including eddies, have the potential to alter productivity and other biogeochemical rates in the ocean. Here, we examine the microbiome of a cyclonic, Gulf Stream frontal eddy, with a distinct origin and environmental parameters compared to surrounding waters, in order to better understand the processes dominating microbial community assembly in the dynamic coastal ocean. Our microbiome-based approach identified the eddy as distinct from the surround Gulf Stream waters. The eddy-associated microbial community occupied a larger area than identified by temperature and salinity alone, increasing the predicted extent of eddy-associated biogeochemical processes. While the eddy formed on the continental shelf, after two weeks both environmental parameters and microbiome composition of the eddy were most similar to the Gulf Stream, suggesting the effect of environmental filtering on community assembly or physical mixing with adjacent Gulf Stream waters. In spite of the potential for eddy-driven upwelling to introduce nutrients and stimulate primary production, eddy surface waters exhibit lower chlorophyll a along with a distinct and less even microbial community, compared to the Gulf Stream. At the population level, the eddy microbiome exhibited differences among the cyanobacteria (e.g. lower Trichodesmium and higher Prochlorococcus) and in the heterotrophic alpha Proteobacteria (e.g. lower relative abundances of specific SAR11 phylotypes) versus the Gulf Stream. However, better delineation of the relative roles of processes driving eddy community assembly will likely require following the eddy and surrounding waters since inception. Additionally, sampling throughout the water column could better clarify the contribution of these mesoscale features to primary production and carbon export in the oceans.


Assuntos
Cianobactérias , Água do Mar , Humanos , Água do Mar/química , Clorofila A , Oceanos e Mares , Temperatura
3.
Food Addit Contam Part B Surveill ; 16(2): 79-85, 2023 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-36537233

RESUMO

A non-targeted convenience survey was conducted in 2021 to estimate the range of total arsenic (As), cadmium (Cd), total mercury (Hg) and lead (Pb) concentrations in ready-to-eat baby foods. Four hundred samples were purchased both online and in brick-and-mortar retail. Samples included both organic and non-organic products, packaged in glass or plastic jars and foil or plastic pouches. Samples were analysed by acid assisted microwave digestion and ICP-MS with an emphasis on ultra-low detection limits. Limits of quantification were 2.26, 1.31, 0.72, and 3.14 µg/kg (ppb) for As, Cd, Hg and Pb, respectively. The median concentrations of As, Cd, Hg, and Pb in tested products were 2.60, 1.81, 0.09, and 1.38 µg/kg, respectively. Foods containing rice were more likely to contain arsenic. Foods with leafy greens, such as spinach and kale, were more likely to contain cadmium and foods with root vegetables had the highest concentrations of lead.


Assuntos
Arsênio , Mercúrio , Cádmio/análise , Arsênio/análise , Chumbo/análise , Contaminação de Alimentos/análise , Alimentos Infantis/análise , Mercúrio/análise
4.
J Hazard Mater ; 439: 129687, 2022 10 05.
Artigo em Inglês | MEDLINE | ID: mdl-36104913

RESUMO

Polymers incorporating quantum dots (QDs) have attracted interest as components of next-generation consumer products, but there is uncertainty about how these potentially hazardous materials may impact human health and the environment. We investigated how the transport (migration) of QDs out of polymers and into the environment is linked to their size and surface characteristics. Cadmium selenide (CdSe) QDs with diameters ranging from 2.15 to 4.63 nm were incorporated into low-density polyethylene (LDPE). Photoluminescence was used as an indicator of QD surface defect density. Normalized migration of QDs into 3% acetic acid over 15 days ranged from 13.1 ± 0.6-452.5 ± 31.9 ng per cm2 of polymer surface area. Migrated QD mass was negatively correlated to QD diameter and was also higher when QDs had photoluminescence consistent with larger surface defect densities. The results imply that migration is driven by oxidative degradation of QDs originating at surface defect sites and transport of oxidation products along concentration gradients. A semi-empirical framework was developed to model the migration data. The model supports this mechanism and suggests that QD surface reactivity also drives the relationship between QD size and migration, with specific surface area playing a less important role.


Assuntos
Compostos de Cádmio , Pontos Quânticos , Compostos de Selênio , Humanos , Tamanho da Partícula , Plásticos , Polímeros
5.
NanoImpact ; 28: 100426, 2022 10.
Artigo em Inglês | MEDLINE | ID: mdl-36096361

RESUMO

We show that inorganic sulfides strongly influence transfer (migration) of nanoparticle mass out of polymer nanocomposites (PNCs) and into aqueous environments. We first manufactured two families of PNCs: one incorporating silver nanoparticles (AgNPs) and one incorporating CdSe quantum dots (QDs). Then, we assessed migration out of these PNCs and into aqueous media containing Na2S at concentrations ranging from 0 to 10-4 M. Results show that Na2S strongly suppressed migration of Ag from AgNP-based PNCs: the migration into water spiked with 10-6 M Na2S was 79% less than migration into water without Na2S, and no migration was detected (LOD ≈ 0.01 ng/cm2) in water spiked with Na2S at 10-5 M or 10-4 M. With CdSe QD-based PNCs, Na2S suppressed Cd migration but enhanced Se migration, resulting in only a small net effect on the total QD migration but a large shift of the leachate composition (from favoring Cd by an average of 5.8 to 1 in pure water to favoring Se 9.4 to 1 when Na2S was present at 10-4 M). These results show that common inorganic substances like sulfides may play a strong role in determining the environmental fate of polymer-dispersed nanoparticles and imply that migration tests conducted in purified water may not always accurately reflect migration into real environments.


Assuntos
Nanopartículas Metálicas , Sulfetos , Plásticos , Cádmio , Prata , Água
6.
Toxicol Sci ; 188(2): 261-275, 2022 07 28.
Artigo em Inglês | MEDLINE | ID: mdl-35708658

RESUMO

Ultrasmall superparamagnetic iron oxide nanoparticles (USPIONs) have been investigated for biomedical applications, including novel contrast agents, magnetic tracers for tumor imaging, targeted drug delivery vehicles, and magneto-mechanical actuators for hyperthermia and thrombolysis. Despite significant progress, recent clinical reports have raised concerns regarding USPION safety related to endothelial cell dysfunction; however, there is limited information on factors contributing to these clinical responses. The influence of USPION surface chemistry on nanoparticle interactions with proteins may impact endothelial cell function leading to adverse responses. Therefore, the goal of this study was to assess the effects of carboxyl-functionalized USPION (CU) or amine-functionalized USPION (AU) (approximately 30 nm diameter) on biological responses in human coronary artery endothelial cells. Increased protein adsorption was observed for AU compared with CU after exposure to serum proteins. Exposure to CU, but not AU, resulted in a concentration-dependent decrease in cell viability and perinuclear accumulation inside cytoplasmic vesicles. Internalization of CU was correlated with endothelial cell functional changes under non-cytotoxic conditions, as evidenced by a marked decreased expression of endothelial-specific adhesion proteins (eg, vascular endothelial-cadherin and platelet endothelial cell adhesion molecule-1) and increased endothelial permeability. Evaluation of downstream signaling indicated endothelial permeability is associated with actin cytoskeleton remodeling, possibly elicited by intracellular events involving reactive oxygen species, calcium ions, and the nanoparticle cellular uptake pathway. This study demonstrated that USPION surface chemistry significantly impacts protein adsorption and endothelial cell uptake, viability, and barrier function. This information will advance the current toxicological profile of USPION and improve development, safety assessment, and clinical outcomes of USPION-enabled medical products.


Assuntos
Nanopartículas , Coroa de Proteína , Humanos , Células Endoteliais/metabolismo , Compostos Férricos/metabolismo , Nanopartículas Magnéticas de Óxido de Ferro , Coroa de Proteína/metabolismo
7.
Front Immunol ; 13: 982082, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-36923728

RESUMO

Emerging cancers are sculpted by neo-Darwinian selection for superior growth and survival but minimal immunogenicity; consequently, metastatic cancers often evolve common genetic and epigenetic signatures to elude immune surveillance. Immune subversion by metastatic tumours can be achieved through several mechanisms; one of the most frequently observed involves the loss of expression or mutation of genes composing the MHC-I antigen presentation machinery (APM) that yields tumours invisible to Cytotoxic T lymphocytes, the key component of the adaptive cellular immune response. Fascinating ethnographic and experimental findings indicate that cannabinoids inhibit the growth and progression of several categories of cancer; however, the mechanisms underlying these observations remain clouded in uncertainty. Here, we screened a library of cannabinoid compounds and found molecular selectivity amongst specific cannabinoids, where related molecules such as Δ9-tetrahydrocannabinol, cannabidiol, and cannabigerol can reverse the metastatic immune escape phenotype in vitro by inducing MHC-I cell surface expression in a wide variety of metastatic tumours that subsequently sensitizing tumours to T lymphocyte recognition. Remarkably, H3K27Ac ChIPseq analysis established that cannabigerol and gamma interferon induce overlapping epigenetic signatures and key gene pathways in metastatic tumours related to cellular senescence, as well as APM genes involved in revealing metastatic tumours to the adaptive immune response. Overall, the data suggest that specific cannabinoids may have utility in cancer immunotherapy regimens by overcoming immune escape and augmenting cancer immune surveillance in metastatic disease. Finally, the fundamental discovery of the ability of cannabinoids to alter epigenetic programs may help elucidate many of the pleiotropic medicinal effects of cannabinoids on human physiology.


Assuntos
Canabinoides , Neoplasias , Humanos , Evasão da Resposta Imune , Imunidade Adaptativa , Canabinoides/farmacologia
8.
Data Brief ; 30: 105548, 2020 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-32382596

RESUMO

This publication reports high resolution mass spectral data for copper chlorophyll and copper chlorophyll degradation products extracted from bright green table olives. These data support analyte identifications made in "Quantitation of copper chlorophylls in green table olives by ultra-high-performance liquid chromatography with inductively coupled plasma isotope dilution mass spectrometry" in the Journal of Chromatography A (Petigara Harp et al., 2020 [1]). Table olive pigments, divided into lipophilic and hydrophilic fractions by liquid-liquid repartition, were separated by ultra-high-performance liquid chromatography and detected by visible wavelength absorbance and high resolution mass spectrometry, using an Orbitrap HF with positive electrospray ionization. Full-scan mass spectra were acquired to assign pigment chemical formulae. Fragment-rich higher-energy collisional dissociation tandem mass spectra were acquired to facilitate structural assignments. Extracted ion chromatograms, full-scan, and tandem mass spectra obtained from representative lipophilic and hydrophilic green table olive extracts are presented in Figures 1-6. Annotated mass spectra comparing experimental and calculated isotope distributions, .raw mass spectral data files, and experimental details linking .raw data files to annotated spectra are provided as Supplementary Material. Spectra extracted from these native data files can be added to mass spectral libraries for use in other studies. Access to native data files uniquely enables rigorous data examination (e.g., molecular ion isotopic distribution, effective mass resolution, presence of overlapping ion series) and use in ways that are not possible when spectra are otherwise reported in simple tables listing mono-isotopic peaks and mass errors. Mass spectra reported here can be used to design multiple-reaction monitoring methods to detect these bright green pigments in agricultural food commodities and finished products.

10.
J Chromatogr A ; 1620: 461008, 2020 Jun 07.
Artigo em Inglês | MEDLINE | ID: mdl-32252985

RESUMO

Table olives, a widely consumed delicacy, are often selected by consumers based on the shade of their green color. The appealing coloration of fresh olives fades to brown or pale yellow during the industrial processing necessary for commercialization and storage, as a result of the degradation of chlorophyll a and b to their corresponding pheophytins and other chlorophyll degradation products (CDP). The re-greening of table olives may be achieved by complexation of CDP with Cu2+, to form stable bright green copper CDP (Cu-CDP) complexes. To study this phenomenon, we developed a novel method to separately extract lipophilic and hydrophilic Cu-CDP and quantify Cu-CDP by UHPLC combined with inductively coupled plasma isotope dilution mass spectrometry (UHPLC-ICP-ID-MS) using post-column isotopic dilution with 65Cu. This technique does not require species-specific calibration standards and was applied to survey the Cu-CDP composition of the various types of table olives sold in the US market. The CDP and Cu-CDP extracted from table olives were identified by high resolution full-scan mass spectrometry. Total elemental Cu in table olives was measured by microwave digestion followed by ICP-MS detection and correlated with the content of Cu-CDP. Pale yellow olives contained <1 mg/kg lipophilic Cu-CDP and <3.5 mg/kg total elemental Cu. Bright green table olives contained 4-22 mg/kg lipophilic Cu-CDP and 14.4-161 mg/kg total elemental Cu in contrast to <6 mg/kg reported for natural abundance, indicating the formation of Cu-CDP was achieved by addition of copper salts. A dark green sample with 2.5 mg/kg of total copper and 0.267 mg/kg lipophilic Cu-CDP may have been processed by addition of sodium copper chlorophyllin (SCC); the higher content of Cu isochlorin e4 compared to Cu 152-Me-chlorin e6 supports this conclusion.


Assuntos
Clorofila/análise , Cromatografia Líquida de Alta Pressão/métodos , Cobre/análise , Espectrometria de Massas/métodos , Sulfato de Cobre/química , Interações Hidrofóbicas e Hidrofílicas , Técnicas de Diluição do Indicador , Isótopos , Olea/química , Porfirinas/química , Sódio/análise
11.
J Card Surg ; 35(4): 738-739, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-32073683

RESUMO

Al Absi and colleagues report their early results of the Fontan procedure in 87 consecutive patients between August 2008 and July 2017 in a tertiary care hospital. The use of the intra/extracardiac fenestration is a promising modification because it is unlikely to be occluded by surrounding tissue and may be associated with decreased pleural effusions, length of hospital stay, and incidence of postoperative arrhythmias.


Assuntos
Técnica de Fontan/métodos , Cardiopatias Congênitas/cirurgia , Arritmias Cardíacas/epidemiologia , Arritmias Cardíacas/prevenção & controle , Humanos , Incidência , Tempo de Internação , Derrame Pleural/epidemiologia , Derrame Pleural/prevenção & controle , Complicações Pós-Operatórias/epidemiologia , Complicações Pós-Operatórias/prevenção & controle , Centros de Atenção Terciária , Fatores de Tempo , Resultado do Tratamento
12.
J Mater Chem B ; 8(6): 1191-1201, 2020 02 14.
Artigo em Inglês | MEDLINE | ID: mdl-31967629

RESUMO

Manganese oxide nanoparticles (MnOx NPs) have been suggested to possess several enzyme-like activities. However, studies often used either color change or fluorescence to determine the catalytic activity. Despite the simplicity and sensitivity of these probes, these methods may give distracting artifacts or not reflect the catalytic activities in biological systems. To address this issue, herein, we used electron spin resonance (ESR) spectroscopy, a technique proven effective in identifying and quantifying the free radicals produced/scavenged in nanomaterial-catalyzed reactions, to systematically evaluate the catalytic activities of three MnOx NPs (MnO2, Mn2O3, and Mn3O4 NPs) towards biologically relevant antioxidants (ascorbate and glutathione (GSH)) and reactive oxygen species (ROS) (hydrogen peroxide (H2O2), superoxide anion, and hydroxyl radical). We found that all three MnOx NPs possess both pro- and anti-oxidant activities, including oxidase-, catalase-, and superoxide dismutase (SOD)-like activities but without peroxidase-like or hydroxyl radical scavenging activity. In addition, there are differences among these MnOx NPs in their catalytic activities towards different reactions. Mn2O3 shows the strongest ascorbate oxidation activity, followed by MnO2 and Mn3O4, while Mn3O4 shows the strongest oxidation efficiency towards GSH compared to Mn2O3 and MnO2. In the catalyzed decomposition of H2O2, MnO2 NPs show higher efficiency in the generation of molecular oxygen than Mn2O3 or Mn3O4. Cellular studies indicate that all three MnOx NPs induced concentration-dependent decreases in the cell viability, with Mn3O4 > Mn3O2 > MnO2. At lower concentrations (<100 µM), consistent with the enzyme-like activities detected in solution, all three NPs significantly decreased H2O2-induced cytotoxicity in Caco-2 cells. Our study determined the multi-enzymatic activities of MnOx NPs and exhibited differences among MnOx NPs of different valences in their enzyme-like activities and their biological implications; these results provide valuable information for safe and efficient applications of MnOx NPs as ROS-scavenging biomedical nanomaterials.


Assuntos
Antioxidantes/farmacologia , Compostos de Manganês/farmacologia , Óxidos/farmacologia , Antioxidantes/química , Células CACO-2 , Sobrevivência Celular/efeitos dos fármacos , Espectroscopia de Ressonância de Spin Eletrônica , Humanos , Peróxido de Hidrogênio/antagonistas & inibidores , Peróxido de Hidrogênio/farmacologia , Compostos de Manganês/química , Oxirredução , Óxidos/química , Tamanho da Partícula , Propriedades de Superfície , Células Tumorais Cultivadas
13.
Artigo em Inglês | MEDLINE | ID: mdl-31230526

RESUMO

Gold nanoparticles (Au NPs) hold great promise in food, industrial and biomedical applications due to their unique physicochemical properties. However, influences of the gastrointestinal tract (GIT), a likely route for Au NPs administration, on the physicochemical properties of Au NPs has been rarely evaluated. Here, we investigated the influence of GIT fluids on the physicochemical properties of Au NPs (5, 50, and 100 nm) and their implications on intestinal epithelial permeability in vitro. Au NPs aggregated in fasted gastric fluids and generated hydroxyl radicals in the presence of H2O2. Cell studies showed that GIT fluids incubation of Au NPs affected the cellular uptake of Au NPs but did not induce cytotoxicity or disturb the intestinal epithelial permeability.


Assuntos
Trato Gastrointestinal/efeitos dos fármacos , Ouro/toxicidade , Nanopartículas Metálicas/toxicidade , Sobrevivência Celular , Trato Gastrointestinal/fisiologia , Humanos , Peróxido de Hidrogênio , Radical Hidroxila , Tamanho da Partícula , Permeabilidade
14.
Pediatr Cardiol ; 40(5): 1057-1063, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-31065759

RESUMO

In complete atrioventricular canal defect (CAVC), there are limited data on preoperative clinical and echocardiographic predictors of operative timing and postoperative outcomes. A retrospective, single-center analysis of all patients who underwent primary biventricular repair of CAVC between 2006 and 2015 was performed. Associated cardiac anomalies (tetralogy of Fallot, double outlet right ventricle) and arch operation were excluded. Echocardiographic findings on first postnatal echocardiogram were correlated with surgical timing and postoperative outcomes using bivariate descriptive statistics and multivariable logistic regression. 153 subjects (40% male, 84% Down syndrome) underwent primary CAVC repair at a median age of 3.3 (IQR 2.5-4.2) months. Median postoperative length of stay (LOS) was 7 (IQR 5-15) days. Eight patients (5%) died postoperatively and 24 (16%) required reoperation within 1 year. On multivariable analysis, small aortic isthmus (z score < - 2) was associated with early primary repair at < 3 months (OR 2.75, 95% CI 1.283-5.91) and need for early reoperation (OR 3.79, 95% CI 1.27-11.34). Preoperative ventricular dysfunction was associated with higher postoperative mortality (OR 7.71, 95% CI 1.76-33.69). Other factors associated with mortality and longer postoperative LOS were prematurity (OR 5.30, 95% CI 1.24-22.47 and OR 5.50, 95% CI 2.07-14.59, respectively) and lower weight at surgery (OR 0.17, 95% CI 0.04-0.75 and OR 0.55, 95% CI 0.35-0.85, respectively). Notably, preoperative atrioventricular valve regurgitation and Down syndrome were not associated with surgical timing, postoperative outcomes or reoperation, and there were no echocardiographic characteristics associated with late reoperation beyond 1 year after repair. Key preoperative echocardiographic parameters helped predict operative timing and postoperative outcomes in infants undergoing primary CAVC repair. Aortic isthmus z score < - 2  was associated with early surgical repair and need for reoperation, while preoperative ventricular dysfunction was associated with increased mortality. These echocardiographic findings may help risk-stratified patients undergoing CAVC repair and improve preoperative counseling and surgical planning.


Assuntos
Defeitos dos Septos Cardíacos/cirurgia , Tempo para o Tratamento , Síndrome de Down/complicações , Ecocardiografia , Feminino , Defeitos dos Septos Cardíacos/diagnóstico por imagem , Humanos , Lactente , Recém-Nascido Prematuro , Masculino , Reoperação , Estudos Retrospectivos , Resultado do Tratamento
15.
J AOAC Int ; 102(2): 590-604, 2019 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-30097073

RESUMO

Background: An interlaboratory study was conducted to test U.S. Food and Drug Administration (FDA) Elemental Analysis Manual (EAM) Method 4.7, "Inductively Coupled Plasma-Mass Spectrometric Determination of Arsenic, Cadmium, Chromium, Lead, Mercury, and Other Elements in Food Using Microwave Assisted Digestion." Objective: The goal of the study was to demonstrate the performance of FDA EAM Method 4.7. Methods: Fourteen laboratories participated in the collaborative study, including nine Food Emergency Response Network state laboratories and five federal FDA laboratories. Laboratories tested 8 labeled standard reference materials and 12 blinded foods: mayonnaise, dark chocolate, sunflower seeds, hamburger with cheese, brown rice flour (blinded reference material included as a test food), infant formula, canned smoked oysters, sardines in tomato paste, swordfish, mineral water, cinnamon, and a multivitamin. The blinded test foods represented every sector of the AOAC food triangle. Participants measured the mass fraction of each element in each sample in triplicate. Results: Horwitz Ratio (HorRat) values were better than 1.5 for all As, Cd, Cu, Hg, Mo, Ni, Pb, and Se measurements when at least eight laboratories reported results greater than LOQ. The HorRat values were better than 1.5 for all Mn and Zn measurements except for the multivitamin and for all Cr measurements except for sunflower seeds, in which the nonhomogeneity was identified. The average HorRat value of the blinded test foods was 0.66 for results greater than LOQ (n = 4206). Conclusions: The study showed that the method performed satisfactorily as a standard method for extractible elemental analysis of food. Highlights: The method met or exceeded the performance expected.


Assuntos
Arsênio/análise , Cádmio/análise , Cromo/análise , Contaminação de Alimentos/análise , Chumbo/análise , Mercúrio/análise , Laboratórios , Espectrometria de Massas , Micro-Ondas , Estados Unidos , United States Food and Drug Administration
16.
Environ Sci Technol ; 52(16): 9468-9477, 2018 08 21.
Artigo em Inglês | MEDLINE | ID: mdl-30004222

RESUMO

We fabricated polymer nanocomposites (PNCs) from low-density polyethylene and CdSe quantum dots (QDs) and used these materials to explore potential exposure after long-term storage in different acidic media that could be encountered in food contact applications. While the low-level release of QD-associated mass into all the food simulants was observed, exposure to dilute acetic acid resulted in more than double the mass transfer compared to that which occurred during exposure to dilute hydrochloric acid at the same pH. Conversely, exposure to citric acid resulted in a suppression of QD release. Permeation experiments and confocal microscopy were used to reveal mechanistic details underlying these mass-transfer phenomena. From this work, we conclude that the permeation of undissociated acid molecules into the polymer, limited by partitioning of the acids into the hydrophobic polymer, plays a larger role than pH in determining exposure to nanoparticles embedded in plastics. Although caution must be exercised when extrapolating these results to PNCs incorporating other nanofillers, these findings are significant because they undermine current thinking about the influence of pH on nanofiller release phenomena. From a regulatory standpoint, these results also support current guidance that 3% acetic acid is an acceptable acidic food simulant for PNCs fabricated from hydrophobic polymers because the other acids investigated resulted in significantly less exposure.


Assuntos
Compostos de Cádmio , Nanocompostos , Pontos Quânticos , Compostos de Selênio , Polímeros
17.
Food Addit Contam Part B Surveill ; 11(2): 92-102, 2018 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-29310543

RESUMO

Cocoa powder and chocolate products are known to sometimes contain cadmium (Cd) and lead (Pb) from environmental origins. A convenience sample of cocoa powder, dark chocolate, milk chocolate, and cocoa nib products was purchased at retail in the US and analysed using inductively coupled plasma mass spectrometry to assess Cd and Pb concentrations. Cd and Pb were evaluated in relation to the percent cocoa solids and to the reported origin of the cocoa powder and chocolate products. Cd ranged from 0.004 to 3.15 mg/kg and Pb ranged from

Assuntos
Bebidas/análise , Cádmio/análise , Doces/análise , Chocolate/análise , Poluentes Ambientais/análise , Contaminação de Alimentos , Chumbo/análise , Métodos Analíticos de Preparação de Amostras , Bebidas/economia , Cádmio/isolamento & purificação , Doces/economia , Chocolate/economia , Laticínios/análise , Laticínios/economia , Países em Desenvolvimento , Poluentes Ambientais/isolamento & purificação , Inspeção de Alimentos , Alimentos em Conserva/análise , Alimentos em Conserva/economia , Internacionalidade , Internet , Chumbo/isolamento & purificação , Limite de Detecção , Maryland , Reprodutibilidade dos Testes , Espectrofotometria Atômica , Estados Unidos
18.
Environ Sci Nano ; 3(3): 657-669, 2016 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-27529026

RESUMO

Concomitant with the development of polymer nanocomposite (PNC) technologies across numerous industries is an expanding awareness of the uncertainty with which engineered nanoparticles embedded within these materials may be released into the external environment, particularly liquid media. Recently there has been an interest in evaluating potential exposure to nanoscale fillers from PNCs, but existing studies often rely upon uncharacterized, poor quality, or proprietary materials, creating a barrier to making general mechanistic conclusions about release phenomena. In this study we employed semiconductor nanoparticles (quantum dots, QDs) as model nanofillers to quantify potential release into liquid media under specific environmental conditions. QDs of two sizes were incorporated into low-density polyethylene by melt compounding and the mixtures were extruded as free-standing fluorescent films. These films were subjected to tests under conditions intended to accelerate potential release of embedded particles or dissolved residuals into liquid environments. Using inductively-coupled plasma mass spectrometry and laser scanning confocal microscopy, it was found that the acidity of the external medium, exposure time, and small differences in particle size (on the order of a few nm) all play pivotal roles in release kinetics. Particle dissolution was found to play a major if not dominant role in the release process. This paper also presents the first evidence that internally embedded nanoparticles contribute to the mass transfer, an observation made possible via the use of a model system that was deliberately designed to probe the complex relationships between nanoparticle-enabled plastics and the environment.

19.
Artigo em Inglês | MEDLINE | ID: mdl-26730958

RESUMO

This work shows a method for the determination of iodine in a variety of food samples and reference materials using inductively coupled plasma-mass spectrometry (ICP-MS) following alkaline extraction. Optimisation of the addition of organic carbon showed that a minimum of 3% 2-propanol was necessary for a constant ratio of iodine to internal standard. The limit of quantification (LOQ), calculated as 30σ for the method, was 36 ng g(-1) in solid food samples. For method validation, seven standard reference materials (SRM) and 21 fortified food samples were used. The precision (%RSD) of the measurements was in the 2-7% range. Accuracies for the SRMs were 85-105%, while the fortified food samples showed 81-119% recoveries, including a number of samples fortified at 50% of the LOQ.


Assuntos
Análise de Alimentos/métodos , Iodo/análise , Espectrometria de Massas
20.
Artigo em Inglês | MEDLINE | ID: mdl-26515534

RESUMO

This paper reports the effects of rinsing rice and cooking it in variable amounts of water on total arsenic, inorganic arsenic, iron, cadmium, manganese, folate, thiamin and niacin in the cooked grain. We prepared multiple rice varietals both rinsed and unrinsed and with varying amounts of cooking water. Rinsing rice before cooking has a minimal effect on the arsenic (As) content of the cooked grain, but washes enriched iron, folate, thiamin and niacin from polished and parboiled rice. Cooking rice in excess water efficiently reduces the amount of As in the cooked grain. Excess water cooking reduces average inorganic As by 40% from long grain polished, 60% from parboiled and 50% from brown rice. Iron, folate, niacin and thiamin are reduced by 50-70% for enriched polished and parboiled rice, but significantly less so for brown rice, which is not enriched.


Assuntos
Arsênio/análise , Culinária , Contaminação de Alimentos/análise , Oryza/química , Vitaminas/análise , Água/química , Grão Comestível/química
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...