Contribution of organic arsenic species to total arsenic measurements using ferrihydrite-backed diffusive gradients in thin films (DGT)

2012 ◽  
Vol 9 (1) ◽  
pp. 55 ◽  
Author(s):  
Heléne Österlund ◽  
Mikko Faarinen ◽  
Johan Ingri ◽  
Douglas C. Baxter
Keyword(s):  
Thin Films ◽  
Natural Waters ◽  
Arsenic Speciation ◽  
Inorganic Arsenic ◽  
Speciation Analysis ◽  
Arsenic Species ◽  
Future Studies ◽  
Organic Arsenic ◽  
Arsenic Determination ◽  
Diffusive Gradients

Environmental contextBoth the mobility and toxicity of arsenic in natural waters are related to the aqueous species distribution. Passive sampling using ferrihydrite-backed diffusive gradients in thin films (DGT) devices has in previous studies been characterised to measure labile inorganic arsenic, and the possible contribution of organic species has been disregarded. This study shows that the two most prevalent organic arsenic species might be included in DGT measurements, which should be taken into consideration when evaluating DGT data in future studies. AbstractIn previous publications discussing arsenic determination using ferrihydrite-backed diffusive gradients in thin films (DGT) devices, organic arsenic forms have been disregarded, even though it is known that the two most prevalent in natural waters, dimethylarsinate (DMA) and monomethylarsonate (MMA), may adsorb to ferrihydrite and thereby be included in the measurement. In this work the accumulation of DMA and MMA, as well as inorganic arsenite and arsenate, to ferrihydrite-backed DGT devices was investigated. It could be demonstrated that MMA, and under acidic conditions also DMA, adsorbed to the binding layer and might therefore contribute to the total mass of measured arsenic. Diffusion coefficients were measured for all four species to enable quantification of DGT-labile concentrations of organic and inorganic arsenic. Elution of the analytes from the ferrihydrite binding layer was performed using 1 mL of 1 M NaOH to facilitate arsenic speciation analysis using chromatographic separation. Average recovery rates were between 87 and 108 %. This study shows that the contribution of DMA and MMA to the total accumulated mass must be taken into consideration when evaluating DGT data in future studies.

Perfluorosulfonated Ionomer-Modified Diffusive Gradients in Thin Films: Tool for Inorganic Arsenic Speciation Analysis

2008 ◽  
Vol 80 (24) ◽  
pp. 9806-9811 ◽  
Author(s):  
Jared G. Panther ◽  
Kathryn P. Stillwell ◽  
Kipton J. Powell ◽  
Alison J. Downard
Keyword(s):  
Thin Films ◽  
Arsenic Speciation ◽  
Inorganic Arsenic ◽  
Speciation Analysis ◽  
Perfluorosulfonated Ionomer ◽  
Diffusive Gradients

Measurement of labile arsenic speciation in water and soil using diffusive gradients in thin films (DGT) and X-ray absorption near edge spectroscopy (XANES)

2015 ◽  
Vol 12 (2) ◽  
pp. 102 ◽  
Author(s):  
Trang Huynh ◽  
Hugh H. Harris ◽  
Hao Zhang ◽  
Barry N. Noller
Keyword(s):  
Thin Films ◽  
Arsenic Speciation ◽  
Arsenic Species ◽  
Extraction Process ◽  
Atomic Fluorescence Spectrometry ◽  
Dimethylarsinic Acid ◽  
X Ray ◽  
As Species ◽  
Diffusive Gradients ◽  
X Ray Absorption

Environmental context Both inorganic and organic arsenic species are toxic to the environment when labile. The Diffusive Gradients in Thin Films technique, equipped with ferrihydrite binding gel enables measurement of labile arsenic species from water and soil solutions. This study indicated that labile arsenic species are quantitatively adsorbed to the gel, and that they are stable for up to 2 weeks following deployment. Abstract Arsenic speciation was determined in the solution extracted from a ferrihydrite binding gel layer in a DGT unit (FB-DGT) deployed in water using coupled high-performance liquid chromatography and hydride generation atomic fluorescence spectrometry (HPLC-HG-AFS). However, the extent of change in arsenic speciation during the extraction process is unknown. By identifying the arsenic species in the FB-DGT gel directly, using X-ray absorption near edge spectroscopy (XANES) fitting with model arsenic compounds, we obtain a better understanding of the ability of FB-DGT to measure labile arsenic species in solution. The results presented herein confirm that FB-DGT accumulated labile inorganic and methylated arsenic species. Arsenic species bound to the FB-DGT gel were stable for up to 2 weeks following deployment. However, caution should be applied when interpreting the proportion of As species measured by HPLC-HG-AFS in solution extracted from FB-DGT because the distribution of arsenic species in extracted solutions was found to be modified by the extraction process. Some (~20%) of arsenate was converted into arsenite, and a significant amount (~25%) of dimethylarsinic acid (DMAsV) was converted into monomethylarsonic acid (MMAsV) or arsenate (AsV). Only inorganic arsenite (iAsIII) was stable during the extraction process. These findings suggested that, based on the XANES measurement, although As species were quantitatively accumulated in the FB-DGT gel, the FB-DGT technique was still unsuitable for studying As speciation. This is because changes in arsenic speciation were observed to occur during gel extraction, prior to HPLC-HG-AFS measurement, and because the XANES technique is available for routine measurements.

scholarly journals Monitoring Arsenic Species Content in Seaweeds Produced off the Southern Coast of Korea and Its Risk Assessment

Environments ◽  
2020 ◽  
Vol 7 (9) ◽  
pp. 68
Author(s):  
Min-hyuk Kim ◽  
Junseob Kim ◽  
Chang-Hyun Noh ◽  
Seogyeong Choi ◽  
Yong-Sung Joo ◽  
...  
Keyword(s):  
Risk Assessment ◽  
South Korea ◽  
Arsenic Speciation ◽  
Arsenic Exposure ◽  
Inorganic Arsenic ◽  
Speciation Analysis ◽  
Arsenic Species ◽  
Dimethylarsinic Acid ◽  
Concentration Data ◽  
Seaweed Species

Seaweed, a popular seafood in South Korea, has abundant dietary fiber and minerals. The toxicity of arsenic compounds is known to be related to their chemical speciation, and inorganic arsenic (iAs) is more detrimental than other species. Due to the different toxicities of the various chemical forms, speciation analysis is important for evaluating arsenic exposure. In this study, total arsenic (tAs) and six arsenic species (arsenite, arsenate, monomethylarsonic acid, dimethylarsinic acid, arsenobetaine, and arsenocholine) were analyzed in 180 seaweed samples. Although there were differences between seaweed species, the concentration of tAs was detected at levels ranging from 1 to 100 µg/g, and the distribution of six arsenic species differed depending on the seaweed species. No correlation between the concentration of iAs and tAs was found in most seaweed species. Through statistical clustering, hijiki and gulfweed were seen to be the seaweeds with the highest ratios of iAs to tAs. Using the iAs concentration data from the arsenic speciation analysis, a risk assessment of seaweed intake in South Korea was conducted. The margin of exposure values showed no meaningful risk for the general population, but low levels of risk were identified for seaweed consumers, with high intakes of gulfweed and hijiki.

scholarly journals Arsenic speciation in food chains from mid-Atlantic hydrothermal vents

2012 ◽  
Vol 9 (2) ◽  
pp. 130 ◽  
Author(s):  
Vivien F. Taylor ◽  
Brian P. Jackson ◽  
Matthew R. Siegfried ◽  
Jana Navratilova ◽  
Kevin A. Francesconi ◽  
...  
Keyword(s):  
Stable Isotope ◽  
Deep Sea ◽  
Hydrothermal Vents ◽  
Arsenic Speciation ◽  
Inorganic Arsenic ◽  
Food Sources ◽  
Arsenic Compounds ◽  
Marine Animals ◽  
Δ13c And Δ15n ◽  
Organic Arsenic

Environmental contextArsenic occurs in marine organisms at high levels and in many chemical forms. A common explanation of this phenomenon is that algae play the central role in accumulating arsenic by producing arsenic-containing sugars that are then converted into simpler organic arsenic compounds found in fish and other marine animals. We show that animals in deep-sea vent ecosystems, which are uninhabited by algae, contain the same organic arsenic compounds as do pelagic animals, indicating that algae are not the only source of these compounds. AbstractArsenic concentration and speciation were determined in benthic fauna collected from the Mid-Atlantic Ridge hydrothermal vents. The shrimp species, Rimicaris exoculata, the vent chimney-dwelling mussel, Bathymodiolus azoricus, Branchipolynoe seepensis, a commensal worm of B. azoricus and the gastropod Peltospira smaragdina showed variations in As concentration and in stable isotope (δ13C and δ15N) signature between species, suggesting different sources of As uptake. Arsenic speciation showed arsenobetaine to be the dominant species in R. exoculata, whereas in B. azoricus and B. seepensis arsenosugars were most abundant, although arsenobetaine, dimethylarsinate and inorganic arsenic were also observed, along with several unidentified species. Scrape samples from outside the vent chimneys covered with microbial mat, which is a presumed food source for many vent organisms, contained high levels of total As, but organic species were not detectable. The formation of arsenosugars in pelagic environments is typically attributed to marine algae, and the pathway to arsenobetaine is still unknown. The occurrence of arsenosugars and arsenobetaine in these deep sea organisms, where primary production is chemolithoautotrophic and stable isotope analyses indicate food sources are of vent origin, suggests that organic arsenicals can occur in a foodweb without algae or other photosynthetic life.

scholarly journals In Situ Measurement of Thallium in Natural Waters by a Technique Based on Diffusive Gradients in Thin Films Containing a δ-MnO2 Gel Layer

2018 ◽  
Vol 91 (2) ◽  
pp. 1344-1352 ◽  
Author(s):  
Hongmei Deng ◽  
Mengting Luo ◽  
Xinyao Shi ◽  
Paul N. Williams ◽  
Kexin Li ◽  
...  
Keyword(s):  
Thin Films ◽  
Natural Waters ◽  
In Situ Measurement ◽  
Gel Layer ◽  
Diffusive Gradients

scholarly journals Shifting the Specificity of E. coli Biosensor from Inorganic Arsenic to Phenylarsine Oxide through Genetic Engineering

Sensors ◽  
2020 ◽  
Vol 20 (11) ◽  
pp. 3093
Author(s):  
Hyojin Kim ◽  
Yangwon Jeon ◽  
Woonwoo Lee ◽  
Geupil Jang ◽  
Youngdae Yoon
Keyword(s):  
Genetic Engineering ◽  
Inorganic Arsenic ◽  
Arsenic Species ◽  
Coli Cell ◽  
Biological Processes ◽  
Phenylarsine Oxide ◽  
Covalent Bonds ◽  
E Coli ◽  
Organic Arsenic ◽  
The Moment

It has recently been discovered that organic and inorganic arsenics could be detrimental to human health. Although organic arsenic is less toxic than inorganic arsenic, it could form inorganic arsenic through chemical and biological processes in environmental systems. In this regard, the availability of tools for detecting organic arsenic species would be beneficial. Because As-sensing biosensors employing arsenic responsive genetic systems are regulated by ArsR which detects arsenics, the target selectivity of biosensors could be obtained by modulating the selectivity of ArsR. In this study, we demonstrated a shift in the specificity of E. coli cell-based biosensors from the detection of inorganic arsenic to that of organic arsenic, specifically phenylarsine oxide (PAO), through the genetic engineering of ArsR. By modulating the number and location of cysteines forming coordinate covalent bonds with arsenic species, an E. coli cell-based biosensor that was specific to PAO was obtained. Despite its restriction to PAO at the moment, it offers invaluable evidence of the potential to generate new biosensors for sensing organic arsenic species through the genetic engineering of ArsR.

scholarly journals Effect of arsenosugar ingestion on urinary arsenic speciation

1998 ◽  
Vol 44 (3) ◽  
pp. 539-550 ◽  
Author(s):  
Mingsheng Ma ◽  
X Chris Le
Keyword(s):  
Arsenic Speciation ◽  
Inorganic Arsenic ◽  
Sample Pretreatment ◽  
Arsenic Species ◽  
Urine Samples ◽  
Standard Reference Materials ◽  
Dimethylarsinic Acid ◽  
Urinary Arsenic ◽  
Biomarkers Of Exposure

Abstract We developed and evaluated a method for the determination of μg/L concentrations of individual arsenic species in urine samples. We have mainly studied arsenite [As(III)], arsenate [As(V)], monomethylarsonic acid (MMAA), and dimethylarsinic acid (DMAA) because these are the most commonly used biomarkers of exposure by the general population to inorganic arsenic and because of concerns over these arsenic species on their toxicity and carcinogenicity. We have also detected five unidentified urinary arsenic species resulting from the metabolism of arsenosugars. We combined ion pair liquid chromatography with on-line hydride generation and subsequent atomic fluorescence detection (HPLC/HGAFS). Detection limits, determined as three times the standard deviation of the baseline noise, are 0.8, 1.2, 0.7, and 1.0 μ/L arsenic for arsenite, arsenate, MMAA, and DMAA, respectively. These correspond to 16, 24, 14, and 20 pg of arsenic, respectively, for a 20-μL sample injected for analysis. The excellent detection limit enabled us to determine trace concentrations of arsenic species in urine samples from healthy subjects who did not have excess exposure to arsenic. There was no need for any sample pretreatment step. We used Standard Reference Materials, containing both normal and increased concentrations of arsenic, to validate the method. Interlaboratory studies with independent techniques also confirmed the results obtained with the HPLC/HGAFS method. We demonstrated an application of the method to the determination of arsenic species in urine samples after the ingestion of seaweed by four volunteers. We observed substantial increases of DMAA concentrations in the samples collected from the volunteers after the consumption of seaweed. The increase of urinary DMAA concentration is due to the metabolism of arsenosugars that are present in the seaweed. Our results suggest that the commonly used biomarkers of exposure to inorganic arsenic, based on the measurement of arsenite, arsenate, MMAA, and DMAA, are not reliable when arsenosugars are ingested from the diet.

scholarly journals Progress in understanding the use of diffusive gradients in thin films (DGT) – back to basics

2012 ◽  
Vol 9 (1) ◽  
pp. 1 ◽  
Author(s):  
William Davison ◽  
Hao Zhang
Keyword(s):  
Thin Films ◽  
Natural Waters ◽  
Kinetic Studies ◽  
Simple Equation ◽  
Charge Effects ◽  
The Past ◽  
Soils And Sediments ◽  
Rate Of Reaction ◽  
Simple Equations ◽  
Diffusive Gradients

Environmental contextIt is now nearly 20 years since the introduction of the technique of diffusive gradients in thin films, which can provide information on solute concentrations and dynamics in sediments, soils and water. The interpretation of these measurements in terms of concentrations relies on simple equations and associated assumptions. This review examines how well they have stood the test of time. AbstractDiffusive gradients in thin films (DGT) is now widely used to measure a range of determinands in waters, soils and sediments. In most cases the mass accumulated is interpreted in terms of a labile form of the component being measured using a simple equation that applies to steady-state conditions. During the past decade several publications have revealed phenomena that question some of the assumptions necessary for use of the simple equation. This review systematically examines the available evidence relating to appropriate geometry, possible charge effects, binding of solutes and ligands to the diffusive gel and filter, the rate of reaction with the binding layer, the effects of solution complexation and kinetic limitation, necessary time for deployment and the measurement of nanoparticles. DGT emerges as a robust monitoring tool for labile components in solution. Although there is evidence, for some conditions, of binding of metals and, more moderately, humic substances to the diffusive gel and filter membrane, this is unlikely to affect DGT measurement in natural waters for deployment times exceeding a few days. Detailed speciation and kinetic studies require a more thorough interpretation of the mass accumulated by DGT. A coherent theory has emerged for relatively simple solutions, but systems with complex heterogeneous ligands, as is the case for natural waters, are challenging. The size discrimination of DGT is still poorly known. Systematic measurements with well characterised nanoparticles are required to define the distribution of pore sizes in the gels and to establish the contribution of natural colloids to the DGT measurement.

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