Thiol-antioxidants interfere with assessing silver nanoparticle cytotoxicity.

Many studies have shown that silver nanoparticles (AgNP) induce oxidative stress, and it is commonly assumed that this is the main mechanism of AgNP cytotoxicity. Most of these studies rely on antioxidants to establish this cause-and-effect relationship; nevertheless, details on how these antioxidants interact with the AgNP are often overlooked. This work aimed to investigate the molecular mechanisms underlying the use of antioxidants with AgNP nanoparticles. Thus, we studied the molecular interaction between the thiol-antioxidants (N-acetyl-L-Cysteine, L-Cysteine, and glutathione) or non-thiol-antioxidants (Trolox) with chemically and biologically synthesized AgNP. Both antioxidants could mitigate ROS production in Huh-7 hepatocarcinoma cells, but only thiol-antioxidants could prevent the cytotoxic effect, directly binding to the AgNP leading to aggregation. Our findings show that data interpretation might not be straightforward when using thiol-antioxidants to study the interactions between metallic nanoparticles and cells. This artifact exemplifies potential pitfalls that could hinder the progress of nanotechnology and the understanding of the nanotoxicity mechanism.

Comparative in vitro toxicity of a graphene oxide-silver nanocomposite and the pristine counterparts toward macrophages.

BACKGROUND: Graphene oxide (GO) is a highly oxidized graphene form with oxygen functional groups on its surface. GO is an excellent platform to support and stabilize silver nanoparticles (AgNP), which gives rise to the graphene oxide-silver nanoparticle (GOAg) nanocomposite. Understanding how this nanocomposite interacts with cells is a toxicological challenge of great importance for future biomedical applications, and macrophage cells can provide information concerning the biocompatibility of these nanomaterials. The cytotoxicity of the GOAg nanocomposite, pristine GO, and pristine AgNP was compared toward two representative murine macrophages: a tumoral lineage (J774) and peritoneal macrophages collected from Balb/c mouse. The production of reactive oxygen species (ROS) by J774 macrophages was also monitored. We investigated the internalization of nanomaterials by transmission electron microscopy (TEM). The quantification of internalized silver was carried out by inductively coupled plasma mass spectrometry (ICP-MS). Nanomaterial stability in the cell media was investigated overtime by visual observation, inductively coupled plasma optical emission spectrometry (ICP OES), and dynamic light scattering (DLS). RESULTS: The GOAg nanocomposite was more toxic than pristine GO and pristine AgNP for both macrophages, and it significantly induced more ROS production compared to pristine AgNP. TEM analysis showed that GOAg was internalized by tumoral J774 macrophages. However, macrophages internalized approximately 60 % less GOAg than did pristine AgNP. The images also showed the degradation of nanocomposite inside cells. CONCLUSIONS: Although the GOAg nanocomposite was less internalized by the macrophage cells, it was more toxic than the pristine counterparts and induced remarkable oxidative stress. Our findings strongly reveal a synergistic toxicity effect of the GOAg nanocomposite. The toxicity and fate of nanocomposites in cells are some of the major concerns in the development of novel biocompatible materials and must be carefully evaluated.

Method validation for control determination of mercury in fresh fish and shrimp samples by solid sampling thermal decomposition/amalgamation atomic absorption spectrometry.

A method for the determination of total mercury in fresh fish and shrimp samples by solid sampling thermal decomposition/amalgamation atomic absorption spectrometry (TDA AAS) has been validated following international foodstuff protocols in order to fulfill the Brazilian National Residue Control Plan. The experimental parameters have been previously studied and optimized according to specific legislation on validation and inorganic contaminants in foodstuff. Linearity, sensitivity, specificity, detection and quantification limits, precision (repeatability and within-laboratory reproducibility), robustness as well as accuracy of the method have been evaluated. Linearity of response was satisfactory for the two range concentrations available on the TDA AAS equipment, between approximately 25.0 and 200.0 µg kg(-1) (square regression) and 250.0 and 2000.0 µg kg(-1) (linear regression) of mercury. The residues for both ranges were homoscedastic and independent, with normal distribution. Correlation coefficients obtained for these ranges were higher than 0.995. Limits of quantification (LOQ) and of detection of the method (LDM), based on signal standard deviation (SD) for a low-in-mercury sample, were 3.0 and 1.0 µg kg(-1), respectively. Repeatability of the method was better than 4%. Within-laboratory reproducibility achieved a relative SD better than 6%. Robustness of the current method was evaluated and pointed sample mass as a significant factor. Accuracy (assessed as the analyte recovery) was calculated on basis of the repeatability, and ranged from 89% to 99%. The obtained results showed the suitability of the present method for direct mercury measurement in fresh fish and shrimp samples and the importance of monitoring the analysis conditions for food control purposes. Additionally, the competence of this method was recognized by accreditation under the standard ISO/IEC 17025.

Aluminum concentrations in central and peripheral areas of malignant breast lesions do not differ from those in normal breast tissues.

BACKGROUND: Aluminum is used in a wide range of applications and is a potential environmental hazard. The known genotoxic effects of aluminum might play a role in the development of breast cancer. However, the data currently available on the subject are not sufficient to establish a causal relationship between aluminum exposure and the augmented risk of developing breast cancer. To achieve maximum sensitivity and specificity in the determination of aluminum levels, we have developed a detection protocol using graphite furnace atomic absorption spectrometry (GFAAS). The objective of the present study was to compare the aluminum levels in the central and peripheral areas of breast carcinomas with those in the adjacent normal breast tissues, and to identify patient and/or tumor characteristics associated with these aluminum levels. METHODS: A total of 176 patients with breast cancer were included in the study. Samples from the central and peripheral areas of their tumors were obtained, as well as from the surrounding normal breast tissue. Aluminum quantification was performed using GFAAS. RESULTS: The average (mean ± SD) aluminum concentrations were as follows: central area, 1.88 ± 3.60 mg/kg; peripheral area, 2.10 ± 5.67 mg/kg; and normal area, 1.68 ± 11.1 mg/kg. Overall and two-by-two comparisons of the aluminum concentrations in these areas indicated no significant differences. We detected a positive relationship between aluminum levels in the peripheral areas of the tumors, age and menopausal status of the patients (P = .02). CONCLUSIONS: Using a sensitive quantification technique we detected similar aluminum concentrations in the central and peripheral regions of breast tumors, and in normal tissues. In addition, we did not detect significant differences in aluminum concentrations as related to the location of the breast tumor within the breast, or to other relevant tumor features such as stage, size and steroid receptor status. The next logical step is the assessment of whether the aluminum concentration is related to the key genomic abnormalities associated with breast carcinogenesis.

Trace Elements in Soy-Based Beverages: A Comprehensive Study of Total Content and In Vitro Bioaccessibility.

Soy-based beverages are one of the most consumed plant-based beverages, which have been used as a substitute for dairy products. Soy is a source of several nutrients (vitamins, minerals, and phenolic compounds, etc.) and its consumption is usually associated with several benefits, such as the prevention of cardiovascular diseases, cancer, and osteoporosis. However, non-essential trace elements can be found in these beverages. Thus, a comprehensive study concerning trace elements Al, As, Cd, Co, Cr, Cu, Fe, Li, Mn, Ni, Pb, Sb, Se, Sn, Sr, and Zn in soy-based beverages was proposed. In vitro digestion allowed to simulate the gastrointestinal juice (bioaccessibility) and the Caco-2 cells culture model was applied for the bioavailability assay. Trace elements measures were performed by inductively coupled plasma optical emission spectrometry (ICP OES). Multivariate analysis classified soy-based beverages according to their soy source (isolate protein, hydrosoluble extract, and beans); Al, Cu, Fe, Mn, Sr, Se, and Zn bioaccessible fractions corresponded to approximately 40%-80% of their total content, and soy-based beverages were found to be a good Fe, Se, and Zn source. However, our results showed risk exposure assessment from daily consumption of one glass of soy-based beverage can contribute to 3.5% and 0.9% of Al Provisional Tolerable Weekly Intake (PTWI) for children and adults, respectively.

Formulations with microencapsulated Fe-peptides improve in vitro bioaccessibility and bioavailability.

The bioaccessibility and the bioavailability of iron complexed to peptides (active) in microparticles forms contained in dry beverages formulations were evaluated. The peptide-iron complexes microparticles were obtained by spray drying and added in three dry formulations (tangerine, strawberry, and chocolate flavors). The peptides isolated by iron ion affinity (IMAC-Fe III) had their biological activity predicted by BIOPEP® database and were evaluated by molecular coupling. The bioaccessibility was evaluated by solubility and dialysability and the bioavalability was assessed by Caco-2 cellular model. The proportion 10:1 of peptide-iron complexes presented higher rates of bioaccessibility (49%) and bioavailability (56%). The microparticle with peptide-iron complex showed greater solubility after digestion (39.1%), bioaccessibility (19.8%), and bioavailability (34.8%) than the ferrous sulfate salt (control) for the three assays (10.2%; 12.9%; 9.7%, respectively). Tangerine and strawberry formulations contributed to the iron absorption according to the results of bioaccessibility (36.2%, 30.0% respectively) and bioavailability (80.5%, 84.1%, respectively). The results showed that iron peptide complexation and microencapsulation process improve the bioaccessibility and bioavailability when incorporated into formulations.

In vitro and in vivo acute toxicity of a novel citrate-coated magnetite nanoparticle.

Magnetic nanoparticles (MNps) have become powerful tools for multiple biomedical applications such as hyperthermia drivers, magnetic resonance imaging (MRI) vectors, as well as drug-delivery systems. However, their toxic effects on human health have not yet been fully elucidated, especially in view of their great diversity of surface modifications and functionalizations. Citrate-coating of MNps often results in increased hydrophilicity, which may positively impact their performance as drug-delivery systems. Nonetheless, the consequences on the intrinsic toxicity of such MNps are unpredictable. Herein, novel magnetite (Fe3O4) nanoparticles covered with citrate were synthesized and their potential intrinsic acute toxic effects were investigated using in vitro and in vivo models. The proposed synthetic pathway turned out to be simple, quick, inexpensive, and reproducible. Concerning toxicity risk assessment, these citrate-coated iron oxide nanoparticles (IONps) did not affect the in vitro viability of different cell lines (HaCaT and HepG2). Moreover, the in vivo acute dose assay (OECD test guideline #425) showed no alterations in clinical parameters, relevant biochemical variables, or morphological aspects of vital organs (such as brain, liver, lung and kidney). Iron concentrations were slightly increased in the liver, as shown by Graphite Furnace Atomic Absorption Spectrometry and Perls Prussian Blue Staining assays, but this finding was considered non-adverse, given the absence of accompanying functional/clinical repercussions. In conclusion, this study reports on the development of a simple, fast and reproducible method to obtain citrate-coated IONps with promising safety features, which may be used as a drug nanodelivery system in the short run. (263 words).

Trace elements in ready-to-drink ice tea: Total content, in vitro bioaccessibility and risk assessment.

Tea is one of the most consumed non-alcoholic beverages in world and it has been frequently associated to health benefits. Besides its nutrient composition, non-essential trace elements associated with toxic effects may also be present. Ever since food components undergo biotransformation process along gastrointestinal tract after ingestion, it is important to evaluate both total and bioavailable content of trace elements. Therefore, this study aimed to provide comprehensive data concerning the influence of the in vitro digestion on sixteen trace elements present in ready-to-drink ice tea (black, green, mate and white tea). Essential minerals (Co, Cr, Cu, Fe, Mn, Se and Zn) and inorganic contaminants (Al, As, Cd, Li, Ni, Pb, Sb, Sn and Sr) contents were determined by ICP OES after microwave acid digestion. Bioaccessibility evaluation was carried out by simulating the gastric (pepsin) and intestinal juice (pancreatin and bile salts) and bioavailability used Caco-2 cells culture as an intestinal epithelial model. Moreover, tannins were evaluated by UV-VIS spectroscopy. Multivariate analysis allowed classifying ice tea samples in three groups, based on their trace elements profile. Al, Cu, Sr, Mn and Zn bioaccessible fractions corresponded to, approximately, 40-60% of their total content. For Mn, bioaccessibility and bioavailability presented the same pattern (green ice tea > black ice tea > mate ice tea) whilst Sr bioavailability in green tea were 50% higher than in black tea samples.

Bioavailability Assessment of Copper, Iron, Manganese, Molybdenum, Selenium, and Zinc from Selenium-Enriched Lettuce.

Cu, Fe, Mn, Mo, Selenium (Se), and Zn bioavailability from selenate- and selenite-enriched lettuce plants was studied by in vitro gastrointestinal digestion followed by an assay with Caco-2 cells. The plants were cultivated in the absence and presence of two concentrations (25 and 40 µmol/L of Se). After 28 days of cultivation, the plants were harvested, dried, and evaluated regarding the total concentration, bioaccessibility, and bioavailability of the analytes. The results showed that biofortification with selenate leads to higher Se absorption by the plant than biofortification with selenite. For the other nutrients, Mo showed high accumulation in the plants of selenate assays, and the presence of any Se species led to a reduction of the plant uptake of Cu and Fe. The accumulation of Zn and Mn was not strongly influenced by the presence of any Se species. The bioaccessibility values were approximately 71%, 10%, 52%, 84%, 71%, and 86% for Cu, Fe, Mn, Mo, Se, and Zn, respectively, and the contribution of the biofortified lettuce to the ingestion of these minerals is very small (except for Se and Mo). Due to the low concentrations of elements from digested plants, it was not possible to estimate the bioavailability for some elements, and for Mo and Zn, the values are below 6.9% and 3.4% of the total concentration, respectively. For Se, the bioavailability was greater for selenite-enriched than selenate-enriched plants (22% and 6.0%, respectively), because selenite is biotransformed by the plant to organic forms that are better assimilated by the cells.

Higher silver bioavailability after nanoparticle dietary exposure in marine amphipods.

On release into surface waters, engineered silver nanoparticles (AgNPs) tend to settle to sediments and, consequently, epibenthic fauna will be exposed to them through diet. We established Ag uptake and accumulation profiles over time in the hemolymph of a marine amphipod fed with a formulated feed containing AgNPs or AgCl. Silver bioavailability was higher in organisms exposed to AgNPs, indicating that the nanoparticles pose a higher risk of toxicity compared to similar concentrations of AgCl. Environ Toxicol Chem 2019;38:806-810. © 2019 SETAC.

Investigation of twelve trace elements in herbal tea commercialized in Brazil.

In this study twelve trace elements were investigated in herbal tea commercialized in Brazil. Boldo, Chamomile, Mate and Peppermint tea samples were acquired in Brazil local markets and both herbs and their infusions were evaluated. Trace elements were classified in two groups: poorly (Al, As, Ba, Cd, Cr, Fe, Pb and Se) and moderately (Cu, Mn, Ni and Zn) extractable. This patterned showed that even levels above threshold established by Brazilian and MERCOSUR regulations were observed in herbal tea (Cd and Pb in 89% and 78% of mate and peppermint tea samples, respectively), their infusions did not presented toxic levels. The estimative of exposure and dietary intake revealed important values for a daily consumption of a single cup of herbal infusion and an unique composition was also verified for herbal tea samples: although age and origin was unavailable, multivariate analysis classified the samples in four distinct groups.

Trace mineral composition of human breast milk from Brazilian mothers.

BACKGROUND: Human milk is a dynamic food and some important differences in composition can be found between the milk from preterm and terms infants. Additionally, in some situations, the mother's own milk is unavailable and the use of milk from human milk banks is considered as the most appropriate substitute. In this way, concentrations of trace elements (Ba, Cu, Fe, Mn, Mo, Se, Sr, and Zn) were determined in human milk, considering the differences about preterm and term human milk and its processing in a human milk bank. METHODS: A total of 156 samples were analyzed, which were divided in three groups: samples collected at the hospital at bedside (BS, 60 samples) from mothers of preterm infants and samples from mothers of term infants collected in a human milk bank without pasteurization (WP, 49 samples) and pasteurized by the Holder procedure (P, 47 samples). The analyzes were conducted by inductively coupled plasma mass spectrometry (ICP-MS) after the treatment of the samples with acid mineralization assisted by microwave radiation. RESULTS: Concentrations varied in a range of 0.6-88.2 µg/L for Ba, 78.6-954.5 µg/L for Cu, 24.2-5229.2 µg/L for Fe, 0.4-42.6 µg/L for Mn, 0.1-39.1 µg/L for Mo, 2.5-70.6 µg/L for Se, 8.9-187.5 µg/L for Sr and 76.3-17727.2 µg/L for Zn. Significant differences (p < 0.05) were found between preterm (BS) and term human milk (WP and P) for Ba, Cu, Mo, Se, and Zn, whereas the processing of the donated milk by Holder pasteurization did not influence the concentration of the studied trace elements. The milk of term infants does not attend the recommended daily intake (RDI) of Zn and for preterm infants the RDI of Fe and Mn is not achieved. CONCLUSIONS: The higher concentrations of Cu, Mo, Se and Zn observed in milk from mothers of preterm infants indicate that the milk to be offered for these high-risk neonates in neonatal intensive care units should contain higher levels of these trace elements. Besides, considering the RDI, the milk of term infants should be fortified with Zn, whereas the milk of preterm infants should be fortified with Fe.

N-Acetylcysteine reverses silver nanoparticle intoxication in rats.

The increasing use of silver nanoparticles (AgNPs) in consumer products raises the risk of human toxicity. Currently, there are no therapeutic options or established treatment protocols in cases of AgNPs intoxication. We demonstrated previously that thiol antioxidants compounds can reverse the cytotoxicity induced by AgNPs in Huh-7 hepatocarcinoma cells. Here, we investigated the use of N-acetylcysteine (NAC) against the systemic toxic effects of AgNPs (79.3 nm) in rats. Biochemical, histopathological, hematological, and oxidative parameters showed that a single intravenous injection of AgNPs (5 mg/kg b.w.) induced deleterious effects such as hepatotoxicity, potentially as a result of AgNPs accumulation in the liver. Treatment with a single intraperitoneal injection of NAC (1 g/kg b.w.) one hour after AgNPs exposure significantly attenuated all toxic effects evaluated and altered the bioaccumulation and release patterns of AgNPs in rats. The findings show that NAC may be a promising candidate for clinical management of AgNPs intoxication.

Risk assessment of cadmium and chromium from chocolate powder.

An evaluation of the exposition of cadmium and chromium via chocolate drink powder consumption was conducted. The element levels were determined in 34 samples of chocolate drink powder samples of several types (traditional, light, diet, and organic) available in the Brazilian market. The samples were previously treated using acid mineralisation assisted by microwave radiation and analysed by graphite furnace atomic absorption spectrometry. Concentrations of Cd were in the range 14-124 and 81-4790 µg kg-1 for Cr. The contributions of daily consumption of chocolate drink powder for children would represent 4-35% of the provisional tolerable weekly intake of Cd and 0.03-0.14% of the tolerable daily intake of Cr. Target hazard quotients lower than 0.04 and 0.001 were obtained for Cd and Cr, respectively, indicating that the exposure to these elements through chocolate drink powder do not present any potential risk to human health.

ELECTROLYTE AND MINERAL COMPOSITION OF TERM DONOR HUMAN MILK BEFORE AND AFTER PASTEURIZATION AND OF RAW MILK OF PRETERM MOTHERS. / COMPOSIÇÃO ELETROLÍTICA E MINERAL DO LEITE DE LACTANTES A TERMO PRÉ E PÓS-PASTEURIZAÇÃO E DE LEITE CRU DE MÃES DE RECÉM-NASCIDOS PRÉ-TERMO.

OBJECTIVE: To determine and compare the concentrations of electrolytes and minerals in three different types of maternal milk samples: term donor milk before pasteurization, term donor milk after pasteurization and raw milk of mothers of preterm newborns at bedside. METHODS: Descriptive cross-sectional study. Concentrations of calcium (Ca), phosphorous (P), magnesium (Mg), sodium (Na) and potassium (K) were measured in random samples of three human breast milk groups. Samples were analyzed using acid mineralization assisted by microwave radiation and further analysis by inductively coupled plasma optical emission spectrometry. Concentrations were expressed in mg/L, described as mean and standard deviation. The one-way ANOVA and Tukey's post-test were applied to determine the variability between the means of each group. Significance level was set at 5%. RESULTS: There was a significant reduction in the content of Ca (259.4±96.8 vs. 217.0±54.9; p=0.003), P (139.1±51.7 vs. 116.8±33.3; p=0.004) and K (580.8±177.1 vs. 470.9±109.4; p<0.0001) in donor maternal milk before and after pasteurization. Samples of raw milk presented higher contents of Na than the donated milk (twice). The elements P and Ca would only reach the daily intake levels recommended by the European Society of Pediatric Gastroenterology, Hepatology and Nutrition if at least 60 mL of milk could be offered every 3 hours. Mg levels were not different between the three groups. CONCLUSIONS: There was a significant reduction in Ca, P and K levels in samples after pasteurization. The Na value in raw milk, collected at bedside, was higher than in the samples of donor's milk before pasteurization.

OBJETIVO: Determinar e comparar as concentrações de eletrólitos e minerais no leite humano em três grupos: amostras analisadas antes e após pasteurização de lactantes doadoras a termo e amostra de leite cru colhida à beira do leito de mães de recém-nascidos pré-termo. MÉTODOS: Estudo descritivo de corte transversal. Foram dosadas concentrações de cálcio (Ca), fósforo (P), magnésio (Mg), sódio (Na) e potássio (K) em amostras aleatórias de leite humano nos três grupos. As amostras foram analisadas por mineralização ácida assistida por radiação micro-ondas e posteriormente por espectrometria de emissão óptica com plasma indutivamente acoplado e expressas em mg/L, com cálculo de médias e desvio padrão. A comparação entre os grupos foi feita por análise de variância (ANOVA)/teste de Tukey. Nível de significância aceito de 5%. RESULTADOS: Observou-se redução significante dos teores de Ca (259,4±96,8 vs. 217,0±54,9; p=0,003), P (139,1±51,7 vs. 116,8±33,3; p=0,004) e K (580,8±177,1 vs. 470,9±109,4; p<0,0001) após a pasteurização. As amostras de leite cru colhidas à beira do leito apresentaram teores estatisticamente mais elevados de Na (2 vezes) do que o leite a termo de doadora. Ca e P só atingiriam a ingestão recomendada pela European Society of Pediatric Gastroenterology, Hepatology and Nutrition se o leite materno fosse ofertado em volume de 60 mL a cada 3 horas. Concentrações de Mg não diferiram entre os grupos. CONCLUSÕES: Houve uma redução significativa de Ca, P e K nas amostras após pasteurização e os valores de Na no leite cru coletado à beira do leito foram superiores àqueles pré-pasteurização.

Selenium Bioaccessibility and Speciation in Selenium-Enriched Lettuce: Investigation of the Selenocompounds Liberated after in Vitro Simulated Human Digestion Using Two-Dimensional HPLC-ICP-MS.

The evaluation of selenium-enriched vegetables as potential dietary sources of selenium, an essential element for humans, requires an assessment of the plant's accumulation ability as well as of the bioaccessibility and speciation of the accumulated selenium, which influence its biological effects in humans. Lettuce hydroponically grown at three selenite (SeVI)/selenate (SeIV) amendment levels was characterized accordingly. Selenium accumulation in lettuce leaves was greatest with Se(VI) amendment, whereas bioaccessibility was 70% on average in both cases. Selenium speciation in gastrointestinal hydrolysates, characterized by anion and cation exchange HPLC-ICP-MS, showed that Se(IV) was largely biotransformed into organoselenium metabolites, with selenomethionine accounting for 1/3 of the total detected species, whereas Se(VI) was incorporated as such in the edible portion of the plant, with only a small fraction (∼20%) converted into organic species. Taking into account both nutritional quality and safety, the Se(IV)-enriched lettuce appeared more favorable as a potential selenium source for human consumption.

Fractionation of inorganic arsenic by adjusting hydrogen ion concentration.

The inorganic fraction of arsenic species, iAs=∑[As(III)+As(V)] present in fish samples can be quantified in the presence of other arsenic species also found in fishes, such as: monomethylarsonic acid (MMA), dimethylarsinic acid (DMA) and arsenobetaine (AsB). The toxic arsenic fraction was selected taking into account the dissociation constants of these arsenic species in different hydrogen ions concentration leading to the arsine formation from iAs compounds detected as As(III) by HG AAS. For thus, a microwave assisted extraction was carried out using HCl 1molL(-1) in order to maintain the integrity of the arsenic species in this mild extraction media. Recovery experiments were done for iAs fraction, in the presence of other arsenic species. The recovery values obtained for iAs fraction added were quantitative about 87-107% (for N=3, RSD⩽3%). The limit of detection (LOD), and the limit of quantification (LOQ), were 5µgkg(-1) and 16µgkg(-1) respectively.

Cadmium and lead in chocolates commercialized in Brazil.

Cadmium (Cd) and lead (Pb) concentrations and their relationship to the cocoa content of chocolates commercialized in Brazil were evaluated by graphite furnace atomic absorption spectrometry (GF AAS) after microwave-assisted acid digestion. Several chemical modifiers were tested during method development, and analytical parameters, including the limits of detection and quantification as well as the accuracy and precision of the overall procedure, were assessed. The study examined 30 chocolate samples, and the concentrations of Cd and Pb were in the range of <1.7-107.6 and <21-138.4 ng/g, respectively. The results indicated that dark chocolates have higher concentrations of Cd and Pb than milk and white chocolates. Furthermore, samples with five different cocoa contents (ranging from 34 to 85%) from the same brand were analyzed, and linear correlations between the cocoa content and the concentrations of Cd (R(2) = 0.907) and Pb (R(2) = 0.955) were observed. The results showed that chocolate might be a significant source of Cd and Pb ingestion, particularly for children.

Evaluation of the bioaccessible fractions of Fe, Zn, Cu and Mn in baby foods.

The bioaccessibility of four essential micronutrients (iron, zinc, copper and manganese) in some baby foods was evaluated using an in vitro gastrointestinal digestion model. For all of the flour-based foods evaluated, the bioaccessibility of Zn was low, while the bioaccessibility of Cu was above 50%. For these samples, the bioaccessibility of Mn was lower than 50%. Two samples composed of oat and rice flour and whole wheat flour demonstrated a lower bioaccessible fraction of Fe (less than 35%), while the sample made with wheat flour showed high Fe bioaccessibility (approximately 80%). For vegetable- and meat-based baby foods, the Fe bioaccessibility was greater than 80% in samples that contained meat and chicken and approximately 20% for the banana-based sample. The bioaccessibility of Zn was small for all of the foods studied, and in some cases, no Zn appeared to be released. The sample containing banana showed 100% Cu bioaccessibility, in contrast to meat and chicken-based samples, whose Cu bioaccessibility values were less than 50%. The opposite effect occurred for Mn, in which samples containing meat and chicken presented a bioaccessible fraction greater than 50% while the banana-based sample had a fraction less than 50%.

Lead biomonitoring in different organs of lead intoxicated rats employing GF AAS and different sample preparations.

An analytical procedure was developed for the determination of lead in different tissues from Wistar Hanover rats, previously intoxicated with lead acetate during a toxicological study. About 25 mg of dried sample (bone, liver, kidney, heart, lung and spleen) were mixed with 8.0 mL of 7.00 mol L(-1) nitric acid and digested using microwave radiation in closed vessel. Except for the bone samples, the other tissues could also be analyzed after alkaline solubilization with TMAH. All the digested or solubilized samples were analyzed by graphite furnace atomic absorption spectrometry. Good accuracy and precision were attained when analyzing reference standard materials (for bone, liver and kidney) and also from addition to recovery experiments (for heart, lung and spleen tissues). The method was applied to samples from nine animals and the results suggested that there is a profile for lead bioaccumulation in these animals, which seemed to adapt themselves to continuous lead exposure.