Tatiana D. Saint'Pierre

Multielemental determination in oil matrices diluted in xylene by ICP-MS with a dynamic reaction cell employing methane as reaction gas for solving specific interferences

The analysis of organic samples by ICP-MS is still a challenge due to the occurrence of non-spectral and spectral interferences, which usually requires time-consuming sample preparation procedures for their minimization. In this work, results are presented on the direct multielemental determination in oil samples after simple dilution in xylene. The solutions were introduced into the plasma by a sample introduction system especially suited for organics, and the operational conditions of the plasma and the dynamic reaction cell were optimized. A central composite design showed that the nebulizer and the auxiliary gas flow rates had a significant influence on interference formation, monitored by Ba++ and LaO+ intensities. The compromised plasma conditions were: RF power of 1300 W and gas flow rates of 0.42 L min−1 for the nebulizer (Ar), 1.1 L min−1 for the auxiliary gas (Ar), and 0.1 L min−1 of O2 used as an additional gas. In order to minimize spectral interferences on Ca, Cr, Fe and Mg, the operational conditions of the dynamic reaction cell, working with methane as reaction gas, were optimized for 56Fe, 52Cr, 40Ca and 24Mg. Two certified reference materials, NIST 1634c (used fuel oil) and NIST 1085b (lubricating oil), were analyzed and the recoveries were in the range of 90% to 110% for most elements, being the sample detection limits between 0.2 μg kg−1 (Cr) and 40 μg kg−1 (Zn). Reliability of the data was also tested by comparing the results for a set of biodiesel samples with those determined by ICP OES and good agreement was obtained for most elements. Differences in the elemental compositions of biodiesel samples produced from different raw materials were observed, suggesting that elemental fingerprinting may be used for source identification.

Sample Preparation for Determination of Rare Earth Elements in Geological Samples by ICP-MS: A Critical Review

The presence of rare earth elements (REE) in geological materials provides important information about the formation and the geochemical processes that rocks undergo. Therefore, there is a constant necessity for accurate data and reliable and fast analytical methods. However, the low concentrations of these elements typically found in rocks require quantification by sufficiently sensitive techniques, such as Inductively Coupled Plasma Mass Spectrometry (ICP-MS). The preparation of these samples to the introduction in ICP-MS is a critical part of the process. Traditional wet dissolution methods, such as acid digestion or alkaline fusion followed by dissolution are mostly employed. The acid digestion requires a mixture of strong acids due to the presence of low soluble constituents common in rock samples, such as silicates or clays. The alkaline fusion is fast and efficient, but the dissolution of the melted material results in solutions with a high amount of total dissolved solids (TDS), which can be a problem due to the possibility of deposition in parts of the ICP-MS. Other instrumental approaches have been spread rapidly, as the coupling of a laser ablation accessory or an electrothermal vaporizer to the ICP-MS, as they can allow the direct sample introduction, or at least with minimum preparation. This paper presents a review of sample preparation methods, aimed at the quantification of rare earth elements by ICP-MS and focusing on works published in the last decade.

Relationship between blood metals and inflammation in taxi drivers.

BACKGROUND Cardiovascular disease is a cause of concern in public health worldwide, reinforcing the need for studies related to the identification of potential agents that contribute to the inflammation process and atherosclerosis. This study aimed to evaluate whether metals are associated with inflammatory and kidney damage and could contribute to the atherosclerosis process. METHODS Blood metals, inflammatory markers, homocysteine, antioxidants and renal markers were measured in 42 taxi drivers and 27 controls (non-occupationally exposed). RESULTS Taxi drivers had increased Hg, As, Pb and Cd levels, however Cu and Zn levels were decreased compared to controls (p<0.05). Hg, As and Pb levels were positively associated with pro-inflammatory cytokines, nitric oxide and negatively associated with glutathione peroxidase. Moreover, Hg, As and Pb presented positive associations with homocysteine, an independent risk factor for atherosclerosis. Regarding markers of kidney function, N-acetyl-beta-d-glucosaminidase levels were increased in taxi drivers and correlated to inflammation markers. CONCLUSION Hg levels were found above the recommended limits in taxi drivers and both Hg and As levels showed associations with inflammatory process, oxidative status and homocysteine. Thus, chemical substances as Hg and As can be considered as additional contributors to the development of cardiovascular diseases.

Are Delta-Aminolevulinate Dehydratase Inhibition and Metal Concentrations Additional Factors for the Age-Related Cognitive Decline?

Aging is often accompanied by cognitive impairments and influenced by oxidative status and chemical imbalances. Thus, this study was conducted to examine whether age-related cognitive deficit is associated with oxidative damage, especially with inhibition of the enzyme delta-aminolevulinate dehydratase (ALA-D), as well as to verify the influence of some metals in the enzyme activity and cognitive performance. Blood ALA-D activity, essential (Fe, Zn, Cu, Se) and non-essential metals (Pb, Cd, Hg, As, Cr, Ni, V) were measured in 50 elderly and 20 healthy young subjects. Cognitive function was assessed by tests from Consortium to Establish a Registry for Alzheimer’s Disease (CERAD) battery and other. The elderly group presented decreased ALA-D activity compared to the young group. The index of ALA-D reactivation was similar to both study groups, but negatively associated with metals. The mean levels of essential metals were within the reference values, while the most toxic metals were above them in both groups. Cognitive function impairments were observed in elderly group and were associated with decreased ALA-D activity, with lower levels of Se and higher levels of toxic metals (Hg and V). Results suggest that the reduced ALA-D activity in elderly can be an additional factor involved in cognitive decline, since its inhibition throughout life could lead to accumulation of the neurotoxic compound ALA. Toxic metals were found to contribute to cognitive decline and also to influence ALA-D reactivation.

Heavy metal contamination in sandy beach macrofauna communities from the Rio de Janeiro coast, Southeastern Brazil

We evaluated concentrations of eight heavy metals Cr, Zn, Pb, Ni, Cu, Cd, Co and V, in tissues of representative macrofauna species from 68 sandy beaches from the coast of Rio de Janeiro state. The links between contamination levels and community descriptors such as diversity, evenness, density and biomass, were also investigated. Metal concentrations from macrofaunal tissues were compared to maximum permissible limits for human ingestion stipulated by the Brazilian regulatory agency (ANVISA). Generalized linear models (GLMs) were used to investigate the variability in macrofauna density, richness, eveness and biomass in the seven different regions. A non-metric multidimensional scaling analysis (n-MDS) was used to investigate the spatial pattern of heavy metal concentrations along the seven regions of Rio de Janeiro coast. Variation partitioning was applied to evaluate the variance in the community assemblage explained by the environmental variables and the heavy metal concentrations. Our data suggested high spatial variation in the concentration of heavy metals in macrofauna species from the beaches of Rio de Janeiro. This result highlighted a diffuse source of contamination along the coast. Most of the metals concentrations were under the limits established by ANVISA. The variability in community descriptors was related to morphodynamic variables, but not with metal contamination values, indicating the lack of direct relationships at the community level. Concentration levels of eight heavy metals in macrofauna species from 68 sandy beaches on Rio de Janeiro coast (Brazil) were spatially correlated with anthropogenic activities such as industrialization and urbanization.

Investigating heavy metal bioaccumulation by macrofauna species from different feeding guilds from sandy beaches in Rio de Janeiro, Brazil

The relationship between metal accumulation and feeding behavior of macrofauna species is a key concept to understand the bioavailability of different metals in the marine environment. We examined and compared the concentrations of eight heavy metals (Cr, Zn, Pb, Ni, Cu, Cd, Co and V) in different feeding guilds of macrofauna species, from a data set including 68 sandy beaches along the Rio de Janeiro coast. For this purpose, macrofauna species were classified in five feeding guild categories: carnivorous, herbivorous, detritivorous, suspensivorous and filter feeders. The coast of Rio de Janeiro was divided into seven regions according to environmental characteristics and historical human activities. For each region, generalized linear models were adjusted to test for differences between feeding guild abundances. Redundancy Analysis was performed to explore the relationship among the feeding guilds composition and the environmental variables. We found high variability in abundance and composition among feeding guilds, linked with environmental heterogeneity. In general, carnivorous species showed a higher heavy metal concentrations compared to other trophic guilds evaluated. However, bioaccumulation across the feeding guild was not the rule and patterns varied across regions. Our hypothesis is that variations are probably related to the different magnitudes of metal contamination along the coast as also in to the trophic structure found in each beach. This data highlighted the crucial role of the relationship between variability of environmental drivers and bioaccumulation in macrofauna species in sandy beaches ecosystem.