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  • 1
    ISSN: 1432-1130
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract In international legislation concerning trace elements in food, in the environment or in occupational health most regulations are based on the total element contents, and are frequently given as maximum limits or guideline levels. In contrast, only few regulations pay attention to the molecular species in which the elements are bound. The international legislation concerning contaminants in food is presently being established in the Codex Alimentarius, which is an independent United Nations organisation under the joint FAO/WHO Food Standards Programme. Development of the Codex General Standard for Contaminants and Toxins in Food provides the framework for future international legislation on metals as contaminants in food. For certain food additives, which include some essential minerals, speciation is an integral part of the set of specification criteria, because only certain defined chemical compounds are permitted as sources of the essential element. The development of more species-specific analytical and toxicological data, and improved communication with legislators will be necessary before it will become possible to lay down species-specific regulations in all the cases where the specialised scientist will consider it reasonable.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1618-2650
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Anion and cation exchange HPLC-ICP-MS was used to separate and detect mixtures of four dimethylarsinyl-riboside derivatives (arsenosugars), in the presence of eight other arsenic species naturally occurring in the marine environment. The separations achieved showed that two arsenosugars 11 and 13 (cf. Table 2) were present in shellfish certified reference materials (CRMs) and in a lobster hepatopancreas CRM. The concentration of the two arsenosugars in the shellfish samples amounts to 18% of the total arsenic as compared to arsenobetaine at 9–13% and dimethylarsinate at 4–9% of the total arsenic. Additionally, a chromatographic peak with the same retention time as that of 2-dimethylarsinylacetic acid was detected in the shellfish samples. Further support of the identity of this peak was gained after spiking the sample extracts with the standard substance which resulted in a single, but larger peak. The indication that this novel arsenical is present in shellfish, and the recently reported finding of arsenocholine in seafood supports a proposed marine biosynthetic pathway of arsenic that includes both of these compounds as the immediate precursors of arsenobetaine, the end-product of the marine arsenic metabolism.
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  • 3
    ISSN: 0268-2605
    Keywords: mushroom ; arsenic speciation ; HPLC-ICP-MS ; dimethylarsinic acid ; arsenobetaine ; trimethylarsine oxide ; toxicological evaluation ; soil contamination ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Samples of the edible mushroom Laccaria amethystina, which is known to accumulate arsenic, were collected from two uncontaminated beech forests and an arsenic-contaminated one in Denmark. The total arsenic concentration was 23 and 77 μg  As g-1 (dry weight) in the two uncontaminated samples and 1420 μg As g-1 in the contaminated sample. The arsenic species were liberated from the samples using focused microwave-assisted extraction, and were separated and detected by anion- and cation-exchange high-performance liquid chromatography with an inductively coupled plasma mass spectrometer as arsenic-selective detector. Dimethylarsinic acid accounted for 68-74%, methylarsonic acid for 0.3-2.9%, trimethylarsine oxide for 0.6-2.0% and arsenic acid for 0.1-6.1% of the total arsenic. The unextractable fraction of arsenic ranged between 15 and 32%. The results also showed that when growing in the highly arsenate-contaminated soil (500-800 μg As g-1) the mushrooms or their associated bacteria were able to biosynthesize dimethylarsinic acid from arsinic acid in the soil. Furthermore, arsenobetaine and trimethylarsine oxide were detected for the first time in Laccaria amethystina. Additionally, unidentified arsenic species were detected in the mushroom. The finding of arsenobetaine and trimethylarsine oxide in low amounts in the mushrooms showed that synthesis of this arsenical in nature is not restricted to marine biota. In order to minimize the toxicological risk of arsenic to humans it is recommended not to consume Laccaria amethystina mushrooms collected from the highly contaminated soil, because of a genotoxic effect of dimethylarsinic acid observed at high doses in animal experiments. © 1998 John Wiley & Sons, Ltd.No Abstract.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1438-2385
    Source: Springer Online Journal Archives 1860-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Description / Table of Contents: Summary A method for the direct determination of chromium in homogeneous samples of milk and milk products is described. Minimum sample handling and prevention of contamination was given priority. After injection of the sample into the graphite furnace, the sample was ashed in a stream of oxygen at 650°C and then further ashed at 1100°C with argon as the purge gas. Zeeman background correction was used in the atomisation step at 2300°C. The detection limit was 0.7 ng/g. Direct detection of chromium in milk, using only argon as purge gas, was inferior. Non-homogeneous and solid samples, e.g. yoghurt with fruit jam and cheese, were ashed under pressure with nitric acid before analysis. The same analytical principle as used for chromium was also used for the analysis of lead and cadmium in the samples. Analytical quality control was performed for both methods and the results are reported. The results for lead, cadmium and chromium in Danish milk and milk products were in the parts per billion or parts per trillion range and compare well with literature data. The intake of lead, cadmium and chromium from milk and milk products is less than 4% of the total Danish dietary intake of these elements. It is concluded that the contribution from milk and milk products to the total intake of lead and cadmium is toxicologically insignificant and that milk and milk products are only a minor source of the essential element chromium.
    Notes: Zusammenfassung Es wird eine Methode zur direkten Bestimmung von Chrom in homogenen Proben von Milch und Milchprodukten beschrieben. Besonderer Wert wurde auf minimalen Arbeitsaufwand und Verhütung der Kontamination gelegt. Nach Injektion der Probe in den Graphitofen wurde die Probe zunächst mit Sauerstoff bei 650°C verascht und nachfolgend bei 1100°C mit Argon als Schutzgas. Bei der Atomisierungsphase bei 2300°C wurde die Zeeman Hintergrundkorrektion angewandt. Die Detektionsgrenze war 0,7 ng/g. Bei alleiniger Verwendung von Argon als Schutzgas war die direkte Bestimmung von Chrom in Milch weniger gut. Nicht homogene und feste Proben wie Yoghurt mit Fruchtmarmelade und Käse wurden vor der Analyse unter Druck mit Salpetersäure verascht. Die analytische Qualitätskontrolle wurde für beide Methoden durchgeführt und die Resultate wurden aufgeführt. Das gleiche analytische Prinzip wie für Chrom wurde für die Analyse von Blei und Cadmium in den Proben angewandt. Die Resultate für Blei, Cadmium und Chrom in dänischer Milch und Milchprodukten lagen im Bereich von 1∶109 oder 1∶1012; sie sind mit den Literaturdaten vergleichbar. Die Aufnahme von Blei, Cadmium und Chrom mit Milch und Milchprodukten beträgt weniger als 4% der gesamten dänischen Aufnahme dieser Elemente in Lebensmitteln. Danach ist die Aufnahme von Blei und Cadmium toxikologisch unbedeutend, auch das essentielle Element Chrom ist für Milch und Milchprodukte ohne Bedeutung.
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  • 5
    ISSN: 1436-5073
    Keywords: arsenic speciation ; ion-pair HPLC ; ion exchange HPLC ; flame atomic absorption spectrometry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Arsenite, arsenate, monomethylarsonate, dimethylarsinate, arsenobetaine, arsenocholine and the tetramethylarsonium ion were subjected to ion-exchange and ion-pair reversed phase HPLC. The ion exchange method was superior in selectivity and time of analysis for the arsenic anions. The ammonium ions used for the ion-pair method only resulted in separation of some of the anionic arsenic compounds. Flame atomic absorption spectrometry was used for on-line arsenic-specific detection.
    Type of Medium: Electronic Resource
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