Rita Cornelis

Guidelines for terms related to chemical speciation and fractionation of elements. Definitions, structural aspects, and methodological approaches (IUPAC Recommendations 2000)

This paper presents definitions of concepts related to speciation of elements, more particularly speciation analysis and chemical species. Fractionation is distinguished from speciation analysis, and a general outline of fractionation procedures is given. We propose a categorization of species according to isotopic composition of the element, its oxidation and electronic states, and its complex and molecular structure. Examples are given of methodological approaches used for speciation analysis. A synopsis of the methodology of dynamic speciation analysis is also presented.

Normal levels of trace elements in human blood plasma or serum

Abstract This review scrutinizes published information on the levels of 18 trace elements in blood plasma or serum of apparently healthy individuals. The disparities between the values reported by different investigators are examined critically. There is solid experimental evidence that much of the existing controversy is due to inadequate sampling and sample handling or to defective analysis. The data show that much work remains to be done to establish the normal levels of most trace elements. The development of adequate measures for contamination control is the most important prerequisite. Efforts should also be directed towards improving the accuracy and precision of the procedures applied.

The glycerol channel Fps1p mediates the uptake of arsenite and antimonite in Saccharomyces cerevisiae

The Saccharomyces cerevisiae FPS1 gene encodes a glycerol channel protein involved in osmoregulation. We present evidence that Fps1p mediates influx of the trivalent metalloids arsenite and antimonite in yeast. Deletion of FPS1 improves tolerance to arsenite and potassium antimonyl tartrate. Under high osmolarity conditions, when the Fps1p channel is closed, wild‐type cells show the same degree of As(III) and Sb(III) tolerance as the fps1Δ mutant. Additional deletion of FPS1 in mutants defective in arsenite and antimonite detoxification partially suppresses their hypersensitivity to metalloid salts. Cells expressing a constitutively open form of the Fps1p channel are highly sensitive to both arsenite and antimonite. We also show by direct transport assays that arsenite uptake is mediated by Fps1p. Yeast cells appear to control the Fps1p‐mediated pathway of metalloid uptake, as expression of the FPS1 gene is repressed upon As(III) and Sb(III) addition. To our knowledge, this is the first report describing a eukaryotic uptake mechanism for arsenite and antimonite and its involvement in metalloid tolerance.

Trace element speciation for environment, food and health.

Trace Elemant Speciation for Environment, Food and Health , Trace Elemant Speciation for Environment, Food and Health , کتابخانه دیجیتال جندی شاپور اهواز

Handbook of Elemental Speciation: Techniques and Methodology

Different techniques and methods have been developed for (15) Cornelis, R., Crews, H., Caruso, J. and Heumann, K., Handbook of elemental speciation: Techniques and methodology, Chapter 5.9. Speciation Analysis by Electrochemical. 1.1.2 Magnetic Sector Field Devices for Elemental and Isotopic Analysis in Handbook of Elemental Speciation: Techniques and Methodology, eds. Indiana University Course C612SPECTROCHEMICAL METHODS OF (22) “Handbook of Spectroscopy (Book Review)”, Andrade, F.J., Ray, S.R., and Hieftje, Seminar: “New Techniques and Instrumentation for Elemental Speciation.”.

A survey of arsenic species in chinese seafood

In the present report, thirty different types of Chinese edible seafood, including brown algae, red algae, fish, crab, shrimp, mussels, oysters, and clams, which are very popular foodstuffs in the Chinese kitchen, were examined for their total content of As as well as its different species. Total arsenic concentration in algae samples was 1.7-38.7 microg/g (dry weight), and 0.086-7.54 microg/g in fish and shellfish (wet weight), respectively. The arsenic species in seafood extracts were determined by using anion and cation exchange high performance liquid chromatography (HPLC) coupled to inductively coupled plasma mass spectrometry (ICPMS). Arsenosugars were detected in all of the extracted algae samples (1.5-33.8 microg/g dry weight) and fish samples (0.018-0.78 microg/g wet weight). Arsenobetaine was detected in all of the extracted fish and shellfish samples (0.025-6.604 microg/g wet weight). In contrast, inorganic arsenic in fish and shellfish samples occurred at levels below 2% of the total arsenic. No inorganic arsenic was detected in the algae samples. This study provides information about the distribution pattern of arsenic species in seafood products. Since the major share of arsenic components in seafood is organic arsenic with a low toxicity, we can conclude that arsenic in seafood does not pose any risk to human health.

Sample contamination as a source of error in trace-element analysis of biological samples.

Trace-element levels estimated by different investigators are often disparate. It is becoming increasingly evident that sample contamination may explain some of the discrepancies. A method has been developed for the direct estimation of potential errors. This shows that extraneous additions occurring during sample collection and preparation may give rise to grossly misleading results on subsequent analysis.

Trace elements in medicine: Speciation: the new frontier

Abstract Speciation of trace elements in body fluids and tissues of defining the many biocomponents to which the trace elements are bound and to explain their mobility, storage, retention and toxicity. Such new frontiers are now open for interdisciplinary research. It is necessary to maintain the integrity of the metal-ligand binding and to check the mass balance of the protein and the trace element throughout the isolation steps. A distinction is made between chemical speciation of the trace element and speciation as a part of cytology. Some methods are discussed for the speciation of As and Cr in serum, together with the limitations of the speciation procedure. It is assumed that the biomolecule and the trace element which are subsequently detected in the same fraction, are indeed associated with one another. This is not necessarily the case, so that confirmation with different means of identification of the biocomponent is imperative. A major problem in speciation work is due to the fact that immense hazards exist for contamination and losses of the trace element. In cytology, meaningful speciation cannot be achieved by ultracentrifugation of the different cell organelles. The best approach nowadays is to use microbeam techniques which are able to locate the trace element in situ, and even to attribute a semiquantitative value to its presence.

Neutron activation analysis for bulk and trace elements in urine

Abstract Problems in sampling urine for trace element analysis by neutron activation are systematically examined. Collection, storage, sample preparation and contamination hazards during irradiation are studied in detail. Three different sizes of urine samples are prepared for analysis, depending on the concentration and nuclear properties of the elements, and suitable multielement doped urine standards are used. As, Br, Ca, Cl, Co, Cr, Cs, Cu, Hg, I, K, Mg, Mn, Na, Rb, Sc and Zn are determined. The extreme care given to sample collection, use of “ultra-clean” vials, and work in a dust-free room, allows consistent values to be obtained over long periods of time. A literature review of the amounts of forty elements present in urine per day is also given.

Arsenic speciation in Chinese seaweeds using HPLC-ICP-MS and HPLC-ES-MS

Three common Chinese edible seaweeds, one brown (Laminaria japonica) and two red (Porphyra crispata and Eucheuma denticulatum), were examined for their total arsenic content. The As species were extracted with yields of 76.4, 69.8 and 25.0%, respectively. Anion-exchange and cation-exchange high-performance liquid chromatography (HPLC) in combination with inductively coupled plasma mass spectrometry (ICP-MS) were used for the separation of the different arsenic species in two of the three seaweed extracts (Laminaria and Porphyra). The main arsenic species in the algal extracts are arseno sugars, although it has been shown that the Laminaria seaweed contains significant amounts of dimethylarsinic acid (DMA). HPLC was coupled with electrospray mass spectrometry (ES-MS) for structural confirmation of the arsenic species. The mass spectrometer settings for the arseno sugars were optimised using standards. The conclusions drawn on the basis of HPLC-ICP-MS were confirmed by the HPLC-ES-MS data. The HPLC-ES-MS method is capable of determining both arseno sugars and DMA in the seaweeds. The unknown compounds seen in the HPLC-ICP-MS chromatogram of Laminaria could not be ascribed to trimethylarsenic oxide or tetramethylarsonium ion.