1,721,005 research outputs found
Ultra-trace heavy metal determination in sea food by differential pulse catalytic voltammetry: application to fishes and bivalve molluscs
No full textThe paper proposes an analytical procedure regarding the voltammetric determination of chromium(VI), copper(II), lead(II), cadmium(II), zinc(II) and mercury(II) by differential pulse catalytic voltammetry (DPCV) in matrices involved in the food chain, but also employed as possible biological monitors for trace metal. The digestion of each matrix was carried out using a concentrated HCl-HNO3-H2SO4 acidic attack mixture. 0.23 mol L-1 dibasic ammonium tartrate buffer pH 4.9 + 5.9x10-2 mol L-1 NaBrO3 was employed as the supporting electrolyte. The voltammetric measurements were carried out using, as working electrodes, a stationary hanging mercury drop electrode (HMDE) [simultaneous determination of Cr(VI), Cu(II), Pb(II), Cd(II) and Zn(II)] and a gold electrode (GE) [determination of Hg(II)], a platinum electrode and Ag⎪AgCl⎪KClsat electrode as auxiliary and reference electrodes, respectively. The analytical procedure has been verified on the standard reference materials Mussel Tissue BCR-CRM 278 and Cod Muscle BCRCRM 422. For all the elements in the certified matrices, the precision as repeatability, expressed as relative standard deviation (sr) was lower than 6 %, while the trueness, expressed as relative error (e) was of the order of 5-6 %. Once set up on the standard reference materials, the analytical procedure was transferred and applied to fishes and molluscs sampled in the Po river mouth area
Toxic Metals in Herbal Medicines. A Review
No full textThe present review proposes an exhaustive focus on what are the metals of interest, and what is the state of the art about analytical methodologies suitable to detect these toxic metals in herbal medicines. This review would also be a stimulus to solicit International Organizations to fill the gap of the lack of strict and comprehensive laws regulating the maximum allowable concentrations for an increasing number of contaminants in these matrices, especially considering their enormous consumption.
Herbal medicines are more and more worldwide used. This fact certainly presents serious problems for the potential human health risks. This is due to the fact that the laws in force generally do not provide for strict quality controls of herbal medicines to certify the concentration of compounds and elements that may be hazardous for human health, and sometimes very severe or even lethal. Heavy metals have a decidedly substantial part of the contaminants in herbal medicines
Toxic Metal Bio-Monitoring: An Innovative Procedure to Get Complete Information on the Long-Term Trend of the Metal Pollution Load in Environmental Ecosystems
No full textIn recent years, rapid spread of toxic metals has occurred in all environmental matrices. The phenomenon started since many decades. Due to their bioaccumulation and toxicity, these contaminants are very dangerous pollutants for human health. The hazardousness of toxic metals is not lower than pesticides. Indeed, toxic metals are perhaps the most important reason of the pollution load in environmental ecosystems; certainly they are among the greatest. They come from almost all human activities: industries, agriculture, vehicular traffic, urban heating and so on.
Pollution of an ecosystem can be caused in many ways, such as direct input through watercourses; for example, the case of aquatic ecosystems. But in general all ecosystems are subjected to pollution caused by atmospheric transport such as particulate or fumes.
In order to evaluate the pollution load of ecosystems, two paths can be followed:
1) determination of pollutant concentrations by timely and repeated sampling in well-defined ecosystem sites;
2) determination of the same pollutants in species that live and are continually present in the same ecosystem (bio-monitoring).
Evidently, punctual determinations cannot provide information to evaluate the long-term trend of the pollution load. This information can only be provided through bio-monitoring campaigns. Several Authors have given this suggestion, but the scientific community did not firmly support it.
For each toxic-metal determination, the present work reports various species employed in bio-monitoring campaigns: mussels, oysters and clams, algae, vegetables, lichens, mosses. For each bio-monitor and for all metals or group of metals, the various analytical techniques and procedures employed are critically discussed. Particular attention is paid to the analytical performance, in terms of accuracy and detectability.
A separate section is dedicated to the analytical procedure for the determination in bio-monitors of new emerging anthropic polluting traffic-related pollutants, i.e., the platinum group metals (platinum, palladium, rhodium, osmium, ruthenium and iridium
Distribution of mercury and other heavy metals in core sediments of the northern Adriatic Sea
No full textSeven sediment cores were collected along a transect about 20 km off from the mouth of the Po River, in the northern Adriatic Sea (Italy). Cores were characterised by different depositional sequences associated with late Pleistocene-Holocene lowstand (LST), transgressive (TST) and highstand (HST) system tracts. Sediment samples were analysed for mercury, copper, nickel, chromium, manganese and iron, as well as for total organic matter. Metal distribution generally showed vertical and spatial variability ascribed to grain size effects with no significant anthropogenic perturbation. Conversely, mercury showed vertical profiles characterised by surface enrichment, with concentrations in the upper layer (50-230 ng g-1) exceeding 3-11 times the background value of 20 ng g-1 determined in bottom cores. Surface maxima were attributed to anthropogenic mercury delivered mainly by the Po River
Application of pyrolysis-gas chromatography-mass spectrometry and multivariate analysis to study bacteria and fungi in biofilms used for bioremediation
No full textBiofilms are communities of microorganisms adhering to a surface and embedded in an extracellular polymeric matrix, frequently associated with disease and contamination, and also used for engineering applications such as bioremediation. A mixed biofilm formed by bacteria and fungi may provide an optimal habitat for addressing contaminated areas. To exploit the potential of natural microbial communities consisting of bacteria and fungi, it is essential to understand and control their formation. In this work, a method to discriminate among bacteria of genera Bacillus, Pseudomonas, Rhodococcus with respect to the fungus Pleorotus in a biofilm by means of pyrolysis-gaschromatography-mass spectrometry and multivariate analysis is reported. Methylated fatty acids were chosen as biomarkers of microorganisms in the pyrolysates. In situ thermal hydrolysis and methylation was applied. Pyrograms were used as fingerprints, thus allowing for the characterization of whole cells analyzed without any sample pretreatment. Normalized pyrographic peak areas were chosen as variables for chemometric data processing. Principal components analysis was applied as a dataexploration tool. Satisfactory results were obtained in analyzing a real biofilm. The influence of growth medium on whole bacteria fatty acid cell composition was also explored
Toxic metals in Camilla sinensis: Analytical Methods, Human Health Risk and Regulations
No full textPersistent toxic substances tend to accumulate in the environment owing to anthropic activities, causing increasing detrimental to food safety. Toxic metals are among the most deleterious pollutants because they concentrate in all environmental matrices, in particular those involved in the food chain where the consequences on human health may be irreversible.
Nutritional supplements, including herbal extract, vitamins, mineral salts, botanical remedies, are certainly an integral part of the food chain. For this reason, great attention has been focused on tea leaves (Camellia sinensis), widely used by the world's population to obtain drinks, generally by infusion.
It should decidedly be emphasized that the concentration of toxic metals in tea should be under the maximum limits allowed by law. The problem is that in the international legislations, laws specifically concerning the tea do not exist. The existing laws in fact provide legal concentration limits for leafy vegetables in general, and only for a few metals. Obviously this is a problem that should be solved, above all by extending the maximum allowable concentration limits to an increasing number of toxic elements, but also by increasing the number of types of plants. Moreover, only in a few cases, regulations provide safe limits, but the analytical techniques useful to check for those limits are not indicated.
The present work proposes an exhaustive focus on what are the metals of interest, and what is the state of the art about analytical methodologies suitable to detect these toxic metals in Camellia sinensis. For all metals or group of metals, various analytical techniques and procedures employed are critically discussed. Particular attention is paid to the analytical performance, in terms of accuracy and detectability.
A separate section is dedicated to the analytical procedure for the determination in Camellia sinensis of new emerging anthropic toxic polluting metals: platinum group metals (platinum, palladium, rhodium, osmium, ruthenium and iridium) and thallium.
This discussion would also be a stimulus to solicit International Organizations to fill the gap of the lack of strict and comprehensive laws regulating the maximum allowable concentrations for an increasing number of contaminants in this matrix, especially considering their enormous daily use
Square wave catalytic adsorptive voltammetric determination of osmium, ruthenium and lead in vegetable environmental bio-monitors
No full textThe present work regards the simultaneous voltammetric determination of Os(VIII), Ru(III) and Pb(II) by square wave catalytic adsorptive voltammetry (SWCAdV) in vegetable environmental bio-monitor matrices. The analytical procedure was verified by the analysis of the standard reference materials: Olive Leaves BCR-CRM 062 and Tomato Leaves NIST-SRM 1573a. Precision and accuracy, expressed as relative standard deviation and relative error, respectively, were generally lower than 6% in all cases, whereas the limits of detection for all elements were lower than 5.0 μg kg-1. Once set up on the standard reference materials, the analytical procedure was transferred and applied to laurel leaves sampled in proximity to superhighway and in the Po river mouth area. A critical comparison with spectroscopic measurements is discussed
Chemometrics for the Direct Analysis of Solid Samples by Spectroscopic and Chromatographic Techniques
No full textThe direct chemical analysis allows investigating samples without altering them, keeping the sample available for further analysis. For the qualitative investigation, analytical procedures like gas-chromatography, Raman microscopy, and Infra Red spectroscopy are available; however, the univariate approach is not exhaustive in the case of very complex matrices. The quantitative approach is still an open issue, due to the strong matrix effect hindering the creation of univariate calibration methods in interpolation mode. The multivariate analysis may be the solution.
Three-way Principal Components Analysis (PCA) allows for comprehension of variables influencing classification. The Partial Least Squares regression (PLS) combined with Discriminant Analysis (DA) allows classifying. Multivariate standard addition calibration based on PLS coupled with Net Analyte Signal (NAS) calculation allows bypassing the matrix effect in quantitative analysis.
This Chapter is focused on the issues mentioned above. Three sections will be presented:
SECTION 1: three-way PCA is applied to the discrimination among bacterial species in samples analyzed as such by pyrolysis gas chromatography-mass spectrometry. Applications to timely analysis of pathogenic microbes are foreseen.
SECTION 2 PLS-DA is applied to Raman spectra to discriminate adulterated beeswaxes from natural ones. This procedure may be implemented to prevent possible adulteration of bees’ products.
SECTION 3 PLS-NAS is applied to ATR spectra to quantify biogenic silica in marine sediments. The new method allows to accurately study the time evolution of primary productivity in the Antarctic basins
OSMIUM, AN EMERGING ANTHROPIC POLLUTING TRAFFIC-RELATED METAL. ANALYTICAL METHODS FOR ITS DETERMINATION IN ENVIRONMENTAL MATRICES OF INTEREST FOR HUMAN HEALTH AND INVOLVED IN THE FOOD CHAIN
No full textIn the environmental field and in the last decade, the scientific attention has been addressed to platinum group metals (PGMs) owing to their increasing concentration in all the environmental matrices. This is due to the increasing use of these metals in several fields as for example production of industrial catalysts, anticancer drugs, jewels, even if in any case the cause of their growing concentrations in the environment is consequence of the compelling employment of autocatalytic converters. In fact the incorrect use “stop and go” of these converters, with consequent deterioration and abrasion, certainly implies a considerable release in the environment of airborne particulate matter at high PGMs concentration, which results to be the greatest, if not the only, source of contamination of the various environmental matrices, i.e. superficial water, soils, sediments, vegetables and so on.
Really, after the first massive use of platinum, palladium and rhodium in the production of autocatalytic converters, there has been a gradual reduction of these PGMs with consequent growing use of iridium, ruthenium and, especially, osmium.
Indeed, in the last decade, and more and more frequently, osmium together with iridium has been employed as alloying with platinum, palladium and rhodium in the manufacturing of autocatalytic converters in order to withstand high temperature and high wear. In fact, osmium in particular is rarely used in its pure state, and it is instead considered an important alloying agent especially in high-wear applications, owing to its strong corrosion resistance even at very high temperatures.
Thus, this work intends to propose voltammetric methods for the osmium determination at ultra-trace level concentration in environmental samples: airborne particulate matter, superficial waters, soils/sediments, vegetables, mussels, clams and algae. To better validate the proposed analytical procedures, a critical comparison with spectroscopic measurements — electro-thermal atomic absorption spectroscopy (ET–AAS) because of its well established and tested robustness — has been also carried out and discussed here, taking into account all the parameters of interest to set-up an analytical method, such as precision and trueness (that together give accuracy), limit of detection and quantification, selectivity and, especially, sensitivity
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