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Total arsenic and arsenic speciation in indigenous food stuffsSadee, Bashdar January 2016 (has links)
The properties of an element are highly dependent on its chemical form, it’s called elemental speciation. This study evaluates the arsenic species found in a range of food stuffs together with growing environments and toxicity issues. Total arsenic concentrations in fish tissue and vegetable crops were determined by ICP-MS following microwave-assisted acid digestion using nitric acid/hydrogen peroxide, trypsin and cellulase enzymatic extraction procedures. The extracted arsenic species were then quantified using HPLC-ICP-MS. A dilute nitric acid (1 % (v/v)) digestion procedure was also used to extract arsenic species from rice and the different parts (root, skin, stem, leaf and grain) of a range of plant crops. The study was extended to include the aqua-regia extractable arsenic content of the soils collected from the area where the plants had been cultivated in the Kurdistan region of Iraq. Irrigation water was also investigated, but found to contain low levels of arsenic. An anion-exchange HPLC-ICP-MS method was developed, using sulphate and phosphate, for the separation and quantification of AsB, MMA, DMA, InAsIII and InAsV. The results obtained for fish samples were in the range of 3.53-98.80 µg g-1 (dry weight) with non-toxic AsB being the predominant species. The InAsV concentration was in the range of 0.1-1.19 µg g-1 for all fish species except for the John Dory which was below the limit of detection (0.027 µg g-1). Total arsenic, arsenic species, and total multi-elements (including Ag, Al, B, Ba, Be, Cd, Co, Cr, Cu, Fe, Mn, Mo, Ni, Pb, Sb, Se, Si, Ti, V and Zn) were determined in rice samples from Kurdistan, Iraq and other regions of geographical origin. The transport of arsenic from the soil and irrigation water into roots, stem, leaf and subsequently into the grain or bean of the plants is important when assessing the potential health risks from food crops. For the soil sample, InAsV was found to be the major species with smaller quantities of InAsIII . After applying a full BCR sequential extraction procedure to the soils, it was found that 7.87 - 21.14 % of the total arsenic was present in an easily acid-soluble extractable form. Finally, a novel method was developed to measure total arsenic and arsenic species associated with vegetative DNA. In rice plant, it was found that InAsV incorporated within the DNA molecule in which it could replace phosphate. It was also found that the concentration of InAsV associated with DNA molecule decreased with decreasing total arsenic in the rice plant from the root to the leaf.
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Impact of Two Water Management Systems on Arsenic Speciation and Microbial Populations in Rice RhizosphereSomenahally, Anil Kumar C. 2010 December 1900 (has links)
Arsenic (As) is a problem with rice production systems throughout the world as high As
concentrations are reported in rice grains originating from several parts of the world. This
characteristic is mainly due to the flooded conditions utilized in rice culture. We hypothesized
that the soluble As concentrations in the rice rhizosphere can be decreased by growing rice more
aerobically through intermittent flooding. Intermittent water management practices might also
change microbial populations in the rice rhizosphere that might potentially impact As chemistry
and bioavailability. Two field-scale experiments were conducted over two years to study the
impact of intermittent and continuous flooding on As speciation and microbial populations in the
rice rhizosphere. As levels and speciation in the rhizosphere soil, root-plaque and pore-water
were determined using a high performance liquid chromatography-inductively coupled plasmamass
spectroscopy (HPLC-ICP-MS). The microbial populations were assessed from the
rhizosphere soil and root-plaque samples using quantitative polymerase chain reaction (qPCR)
and 16S rRNA sequencing. Pore-water and root-plaque total-As concentrations significantly
decreased in the intermittent compared to the continuous flood plots. Inorganic arsenite (iAsIII)
was predominant in pore-water and inorganic arsenate (iAsV) in root-plaque and soil. Rootplaque sequestered significantly higher levels of As (almost tenfold higher) than the adjacent
rhizosphere soil. Grain As concentrations also decreased by 35 to 45 percent in the intermittent
compared to the continuously flooded plots. Organic As species, monomethyl and dimethyl
arsenate were detected in the rhizosphere with relative increases and decreases among the
treatments. Bacteria were the predominant group (91 to 94 percent and 48 to 78 percent of total community
in root-plaque and rhizosphere soils, respectively). Archaea were also a major component of
rhizosphere soil with their populations being higher under continuous flooding. The relative
abundance of iron-reducing bacteria was around 3 to 6 percent of the total community in root-plaque
and around 6 to 6 percent in soil, with significantly lower abundance in the intermittent compared to
the continuously flooded plots. Results of these studies demonstrated that intermittent flooding
could be a potential management option to reduce grain As in rice cultivated on fields with
moderate to high As concentrations.
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Arsenic Speciation In Fish By Hplc-icp-msEroglu Ozcan, Sefika 01 October 2010 (has links) (PDF)
ABSTRACT
ARSENIC SPECIATION IN FISH BY HPLC-ICP-MS
Ö / ZCAN, Sefika Eroglu
M.S., Department of Chemistry
Supervisor: Prof. Dr. O. Yavuz ATAMAN
September 2010, 103 pages
Arsenic speciation in fish samples on the market was performed using isocratic elution with cation exchange column high performance liquid chromatography (HPLC) with inductively coupled plasma mass spectrometry (ICP-MS) detection. Total As concentrations were found by ICP-MS using samples digested by nitric acid-hydrogen peroxide solution using microwave oven digestion / the results were in the range of 1.15-12.6 µ / g/g. Separation of organic arsenicals, namely arsenobetaine (AB), dimethylarsinic acid (DMA) and monomethylarsonic acid (MA), have been achieved in 12 minutes. Freeze-dried samples were extracted by deionized water with a shaker system / the concentrations of AB and DMA in the extract was then determined using HPLC-ICP-MS. The accuracy of the method for determining AB concentration was confirmed using certified reference material (CRM), DOLT 4 (dog fish liver) / for this CRM only preliminary data are available for AB. The arsenic compounds in 6 fish muscle samples were investigated. The predominant arsenic compound found in extracts was AB / the concentrations were in the range of 0.86-12.0 µ / g/g. DMA concentration was 0.40± / 0.03 µ / g/g in one of the samples / in the others it was below the limit of quantation (0.21 µ / g/g).
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Development of analytical methods for the speciation of arsenic in the marine environmentMomplaisir, Georges-Marie January 1995 (has links)
No description available.
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Characterization of Arsenic by High Performance Liquid Chromatography and Inductively Coupled Plasma Mass Spectrometry of Algal Extracts and Water in Evaporation PondsMedley, Christopher M., M.S. January 2012 (has links)
No description available.
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Determination and Speciation of Arsenic in Environmental and Biological SamplesBerg, Tiffany 01 September 2012 (has links)
A method was developed for the determination of total arsenic in rice grain by microwave-assisted digestion inductively coupled plasma mass spectrometry. Standard calibration solutions were matrix-matched with respect to acid concentration and carbon content post-digest. The importance of eliminating the drying step during sample preparation procedures was investigated. The method was validated with spikes containing standard arsenate solutions into the rice matrix, and with certified reference material SRM1568a (rice flour) from NIST. The method was successfully applied to a commercially available rice sample. Four arsenic species [arsenate (As(V)), arsenite (As(III)), dimethylarsinic acid (DMA) and monomethylarsonic acid (MMA)] were extracted from rice grains by microwave-assisted extraction and separated with high performance liquid chromatography inductively coupled plasma mass spectrometry. The method includes a novel sample clean-up step involving a dialysis procedure to decrease the amount of large starch molecules in the injection solution, in order to minimize poor resolution of chromatographic peaks and maximize column life. The method was validated with spikes of standard arsenic solutions, added to the rice matrix before the extraction procedure. Literature reference values for arsenic species quantification in SRM1568a (rice flour) were also compared. This method was successfully applied to a commercially available rice sample. A study into improvements in reverse phase-HPLC separations of arsenic species was conducted. For the first time, a Sunfire C8 column from Waters (Milford, CT) was employed for the separation of arsenic species in rice extracts. This column was compared to a Symmetry C8 column with respect to total elution time, detection limits, interference effects, and column life, and evaluated with respect to peak resolution, shifts in retention times, and peak symmetry.
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ELECTROCHEMICALLY-AIDED CONTROL OF SOLID PHASE MICRO-EXTRACTION (EASPME) USING CONDUCTING POLYMER COATED FIBERCEYLAN, OZCAN January 2003 (has links)
No description available.
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EXTRACTION TECHNIQUES FOR TRACE ELEMENT DETERMINATIONS OF BIOLOGICAL AND ENVIRONMENTAL SAMPLES INCLUDING ELEMENTAL SPECIATION OF LOBSTER USING INDUCTIVELY COUPLED PLASMA - MASS SPECTROMETRYBrisbin, Judith Ann 11 October 2001 (has links)
No description available.
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[en] TRACE ELEMENTS DETERMINATION IN FOODS BY SS-GFAAS AND HG AFS / [pt] DETERMINAÇÃO DE ELEMENTOS TRAÇO EM ALIMENTOS POR SS-GFAAS E HG AFSMARIELA NORMA MATOS REYES 31 August 2007 (has links)
[pt] A qualidade de produtos alimentícios tem recebido especial
atenção devido
a sua importância na nutrição e saúde humanas. Neste
sentido, a determinação
de metais traço em alimentos tem se convertido em
importante campo na análise
de alimentos. Em relação aos óleos vegetais, a sua
composição em termos de
metais traço é um critério relevante para a avaliação da
qualidade, uma vez que
se sabe que estes metais afetam a sua taxa de oxidação,
influenciando as suas
características e no seu armazenamento. Por outro lado,
cereais e outros
alimentos de origem vegetal são especialmente relevantes
na alimentação
humana, uma vez que são a base da dieta de muitas
populações do mundo. No
presente trabalho, foi desenvolvido um método analítico
para determinação
direta de Cu e Ni em óleos vegetais por Espectrometria de
Absorção Atômica no
Forno de Grafite (GFAAS): as amostras foram pesadas
diretamente em uma
plataforma de grafite e introduzidas no atomizador, com o
auxílio de um
acessório de amostragem de sólidos. O programa de
temperatura otimizado
permitiu o uso de soluções de calibração aquosas. A
exatidão do procedimento
foi confirmada pela boa concordância entre os resultados
obtidos pelo
procedimento proposto e por procedimentos comparativos. Os
limites de
detecção foram de 0,001 e 0,002 μg g-1 para Cu e Ni,
respectivamente, nas
amostras originais. Em continuação, empregou-se a técnica
de fluorescência
atômica para a determinação do conteúdo total de As, Sb,
Se, Te e Bi em
amostras vegetais, de cereais e legumes, após calcinação
por via seca. Foram
otimizados os parâmetros relativos a geração dos hidretos,
assim como os
parâmetros de fluorescência. Testes de adição de analito,
assim como a análise
de materiais certificados de referência, garantiram a
exatidão do procedimento.
Os resultados encontrados mostraram que as amostras
estudadas encontraramse
todas, nos limites preconizados pela legislação européia.
Finalmente, uma
metodologia analítica não cromatográfica, rápida, sensível
e simples foi
desenvolvida para a quantificação de espécies tóxicas de
arsênio em arroz,
sêmola, acelga e berinjela. Estas espécies foram extraídas
com H3PO4 1 mol L-1
+ Triton XT-114 0,1%, assistida por ultra-som, seguindo-se
a lavagem com
EDTA 0,1% (m/v). As espécies As(III), As(V), DMA e MMA
foram quantificadas no extrato por espectrometria de
fluorescência atômica por geração de hidretos
utilizando um sistema de equações proporcionais, que
correspondem a quatro
condições experimentais diferentes. Os valores de limite
de detecção do método
foram 1,3 (3,15); 0,9 (2,97); 1,5 (0.46) e 0,6 (0,37) ng g-
1 para As(III), As(V), DMA
e MMA, respectivamente, nas amostras de cereais e
vegetais, expressos em
termos do peso seco da amostra. Os estudos da recuperação
mostraram
porcentagens maiores que 90% para as quatro espécies
consideradas. A análise
de especiação de um material de referência de farinha de
arroz certificado para
arsênio total mostrou resultados coerentes e concordantes
com outros estudos
com ele realizados. / [en] The quality of food products has received a special
attention due to its
influence in the human health and nutrition. Thus, trace
metal determination in
foods has turned an important field in food analysis.
Concerning vegetal oils, its
metal trace metal composition is a criterion for the
assessment of their quality
since it is known that these metals affect their rate of
oxidation, influencing its
characteristics and storage management. As part of the
present work the direct
determination of Cu and Ni in vegetal oils by Graphite
Furnace Atomic Absorption
Spectrometry (GFAAS), using the solid sampling strategy
was developed: The
samples were weighed on a graphite platform boat and
inserted in the graphite
tube. An adequate temperature program allowed the
calibration by external
aqueous calibration curves. A good agreement between the
results arisen from
the proposed and two comparative procedures (EPA 3031 and
EPA 3051)
confirmed the accuracy of the proposed procedure. The
limits of detention in the
original samples were 0.002 and 0.001 ìg g-1 for Cu and
Ni, respectively. A
second part of the work has dealt with the determination
of the total content of
As, Sb, Se, Te and Bi in samples of vegetable, cereals and
pulses by HG AFS.
The samples were dry ashed by a proper ashing program, and
the hydride
generation parameters were optimized, as well as those
related to the
fluorescence emission. Recovery testes and the analysis of
certified reference
materials testified the accuracy of the procedure. The
content of the studied
elements in studied samples were all below those of the
European regulation.
Finally, a fast, sensitive and simple non chromatographic
methodology was
developed for the speciation analysis of toxic arsenic
species in rice, wheat
semolina, chard and aubergines samples. Ultrasound
assisted extraction of the
toxic arsenic species was carried with 1 mol of L-1 H3PO4
and 0.1% (m/v) Triton
XT-114. After the extraction, As(III), As(V), DMA and MMA
were quantified by
hydride generation atomic fluorescence spectrometry at
four different
experimental conditions. The fluorescence intensities
derived from these four
measurements were introduced in a system of four
proportional equations,
permitting the calculation of the individual species
concentration.. The detection
limits were 1.3 (3.2), 0.9 (3.0), 1.5 (0.5)) and 0.6 (0,5)
ng g-1 for As(III), As(V), DMA and MMA, respectively in
the cereals and (vegetable) samples, expressed
in terms of the dry weight. Recoveries greater than 90%
for the four considered
species in samples spiked at 100 ng g-1 level were
obtained as well as the
assurance of no species interconversion. The speciation
analysis of a rice flour
reference material certified for total arsenic led to
coherent results, which were
also in agreement with other speciation studies made on
the same CRM.
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Especiação química do arsênio por HPLC/ICP/MS em alimentos sem glúten derivados do arroz / Chemical speciation of arsenic by HPLC/ICP/MS in non-gluten foods derived from riceSilva, Juliana Monteiro Bastos da January 2014 (has links)
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Previous issue date: 2014 / Fundação Oswaldo Cruz. Instituto Nacional de Controle de Qualidade em Saúde. Programa de Pós-Graduação em Vigilância Sanitária. Rio de Janeiro, RJ, Brasil. / O arsênio (As) é um elemento químico importante para a saúde do homem sendo considerado como reconhecidamente carcinogênico para humanos. Está amplamente disseminado no ambiente e chega ao homem através das águas e dos alimentos. Dos alimentos de origem terrestre, o arroz tem significativa importância devido à sua capacidade de acumular o As em concentrações muito mais elevadas que o trigo ou o centeio e capazes de impactar a saúde dos consumidores. Os efeitos biológicos do As estão intimamente relacionados às suas formas químicas e a seus estados de oxidação (especiação química). Em geral seus compostos inorgânicos são mais tóxicos que os orgânicos e os sais de As (III) são mais tóxicos que os de As (V). Com a finalidade de sugerir um valor provisório, para a ingestão semanal máxima tolerável de As inorgânico, o Comitê Conjunto de Especialistas sobre Aditivos em Alimentos da Organização Mundial da Saúde/Organização das Nações Unidas para Alimentação e Agricultura (JECFA/FAO/WHO) recomendou recentemente através do Codex Alimentarius o limite máximo permissível em arroz de 0,3 mg kg-1 para As total ou inorgânico, valor também adotado pela ANVISA. De acordo com o relatório de Março de 2012 do Comitê do Codex de Contaminantes em Alimentos das Nações Unidas para Alimentação e Agricultura (JECFA/FAO/WHO), no Brasil faz-se apenas determinação de As total. Com o intuito de contribuir para suprir esta lacuna, este trabalho foi realizado. Para isso, estudou-se a aplicabilidade de um método de determinação da concentração de As total avaliando-se seu comportamento frente a 4 amostras certificadas de farinha de arroz. Os resultados obtidos, sempre superiores a 92% de recuperação, atestam a validade deste método. Em seguida, 24 amostras de produtos sem glútem, adquiridos no comércio foram analisadas e os resultados situaram-se entre 33 e 301 mg kg-1. Das amostras analisadas, 2 encontram-se acima dos limites recomendados. Procedimento semelhante foi utilizado nos estudos da especiação quando avaliou-se 16 amostras adquiridas no comércio. Obteve-se resultados compatíveis com os relatados nos materiais certificados mas observou-se grande variabilidade (de 13 a 97%) quando o somatório das frações foram comparados às concentrações de As total mostrando significativos efeitos matriciais. / Arsenic is toxicologically, a very important chemical element. It is classified as group 1 carcinogen by the IARC. This element is widely dispersed on the environment and it can reach the man through ingestion of contaminated water or food. Among the terrestrial foodstuffs, rice is the most important since it can concentrate As from the soil at levels sufficient high to impact the human health. The biological effects of this element are dependent of its chemical forms (speciation). It is know that in general, the inorganic forms are much more hazardous than the organic ones. In order to prevent any health effects caused by ingestion of As contaminated food, the Codex Alimentarius, published by JEFCA/WHO/FAO, recently recommended as maximum allowed intake of As via rice as 300 mg.kg-1. The Brazilian Health Authority (ANVISA) also recommends this value. According to the “Proposed draft maximum levels for arsenic in rice” published by the Codex Alimentarius Commission entitled published in March 2012, in Brazil only the concentration of total arsenic is measured. In order to contribute to fill this gap this work was carried out. In this study the applicability of a selected methodology for total As determination was evaluated and 4 certified reference materials were used in this step. The obtained results were consistently > 95% of recovering assuring the good performance of this methodology. In advance, 24 samples of commercial products without gluten collected in the market were evaluated and the obtained results were from 33 to 301 mg.kg-1 being 2 of those samples with concentration higher than the recommended value. Identical procedure was used on speciation studies. In this case, 16 samples were evaluated and the content of total As was compared with the summation of concentration of all As forms present. A great variability ranging from 13 to 97% was obtained showing great interference of the product matrix.
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