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ABSTRACT: The Bacillus fusiformis (BFN) strain and its biodegradation of phenol when iron-based nanoparticles such as nanoscale zero-valent iron (nZVI) and Ni/Fe nanoparticles (Ni/Fe) were present at different pH values (6.0, 8.0, and 3.0) were investigated. The growth of BFN and its biodegradation of phenol accelerated in the presence of nZVI and Ni/Fe both at pH 8.0 and pH 6.0. The H2 generated by the corrosion of iron can be used as an electron donor and source of energy for growing BFN. However, only nZVI improved the biodegradation of phenol at pH 3.0, which is most likely due to the increasing medium pH value resulting from the generation of OH(-) as a result of iron corrosion. The images from scanning electron microscopy (SEM) and energy dispersive spectrometer (EDS) demonstrated that these iron-based nanoparticles adhered to the surface of BFN, but no significant change in the morphology of BFN was observed.
Bioresource technology 03/2013; 136C:588-594. · 4.25 Impact Factor
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ABSTRACT: Kaolinite-supported nanoscale zero-valent iron (K-nZVI) was successfully synthesized as a multifunctional composite and used for the degradation of crystal violet (CV). The presence of kaolinite not only decreased the aggregation of zero-valent iron nanoparticles (nZVI) with maintenance of reactivity, but also facilitated reaction by increasing the local concentration of CV in the vicinity of nZVI as an adsorbent. This was confirmed by scanning electron microscopy (SEM) and batch experiments, which showed that 97.23% of CV was removed using K-nZVI, while only 78.72% and 39.22% of CV were removed using nZVI and kaolinite after 30min, respectively. Different factors impacting on degradation of CV were investigated as well. On the basis of these results, a removal mechanism was proposed including: (i) prompt adsorption of CV to the K-nZVI phase, and (ii) reduction of CV by Fe(0) on K-nZVI. Furthermore, different adsorption and reduction kinetics were employed to examine the removal process of CV, where a better fit with the pseudo-second-order model for adsorption and pseudo-first-order model for reduction process was observed, and reduction was the rate limiting step. In addition, isotherm and thermodynamic parameters were evaluated for a specific study of the important adsorption step. Finally, the application of K-nZVI to treat wastewater showed the removal efficiency higher than 99.9%.
Journal of Colloid and Interface Science 02/2013; · 3.07 Impact Factor
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ABSTRACT: Clays such as kaolin, bentonite and zeolite were evaluated as support material for nanoscale zero-valent iron (nZVI) to simultaneously remove Cu(2+) and Zn(2+) from aqueous solution. Of the three supported nZVIs, bentonite-supported nZVI (B-nZVI) was most effective in the simultaneous removal of Cu(2+) and Zn(2+) from a aqueous solution containing a 100 mg/l of Cu(2+) and Zn(2+), where 92.9 % Cu(2+) and 58.3 % Zn(2+) were removed. Scanning electronic microscope (SEM) revealed that the aggregation of nZVI decreased as the proportion of bentonite increased due to the good dispersion of nZVI, while energy dispersive spectroscopy (EDS) demonstrated the deposition of copper and zinc on B-nZVI after B-nZVI reacted with Cu(2+) and Zn(2+). A kinetics study indicated that removing Cu(2+) and Zn(2+) with B-nZVI accorded with the pseudo first-order model. These suggest that simultaneous adsorption of Cu(2+)and Zn(2+) on bentonite and the degradation of Cu(2+)and Zn(2+) by nZVI on the bentonite. However, Cu(2+) removal by B-nZVI was reduced rather than adsorption, while Zn(2+) removal was main adsorption. Finally, Cu(2+), Zn(2+), Ni(2+), Pb(2+) and total Cr from various wastewaters were removed by B-nZVI, and reusability of B-nZVI with different treatment was tested, which demonstrates that B-nZVI is a potential material for the removal of heavy metals from wastewaters.
Environmental Science and Pollution Research 11/2012; · 2.65 Impact Factor
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ABSTRACT: This study evaluated the potential of monitored natural attenuation (MNA) as a remedial option for groundwater at a long-term petroleum hydrocarbon contaminated site in Australia. Source characterization revealed that total petroleum hydrocarbons (TPH) as the major contaminant of concern in the smear zone and groundwater. Multiple lines of evidence involving the geochemical parameters, microbiological analysis, data modelling and compound-specific stable carbon isotope analysis all demonstrated natural attenuation of hydrocarbons occurring in the groundwater via intrinsic biodegradation. Groundwater monitoring data by Mann-Kendall trend analysis using properly designed and installed groundwater monitoring wells shows the plume is stable and neither expanding nor shrinking. The reason for stable plume is due to the presence of both active source and natural attenuation on the edge of the plume. Assuming no retardation and no degradation the contaminated plume would have travelled a distance of 1,096 m (best case) to 11,496 m (worst case) in 30 years. However, the plume was extended only up to about 170 m from its source. The results of these investigations provide strong scientific evidence for natural attenuation of TPH in this contaminated aquifer. Therefore, MNA can be applied as a defensible management option for this site following significant reduction of TPH in the source zone.
Biodegradation 08/2012; 23(6):881-95. · 2.02 Impact Factor
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ABSTRACT: The strain, Burkholderia vietnamiensis C09V was immobilized on PVA-alginate-kaolin gel beads as a biomaterial to improve the degradation of crystal violet from aqueous solution. The results show that 98.6% (30 mg L(-1)) crystal violet was removed from aqueous solution using immobilized cells on PVA-alginate-kaolin gel beads, while 94.0% crystal violet was removed by free cells after degradation at the pH 5 and 30°C for 30 h. Kinetics studies show that the pseudo-second-order kinetics well described the adsorption of crystal violet on the PVA-alginate-kaolin beads. Biodegradation of crystal violet on immobilized cells was fitted well by first-order reaction kinetics, indicating that CV was adsorbed onto kaolin and followed their degradation by immobilized cells onto the the PVA-alginate-kaolin beads. Characterization with SEM shows that cells attached well to the surface of PVA-alginate-kaolin beads, leading to improved crystal violet transfer from aqueous solution to immobilized cells. In addition, UV-vis show that the absorption peak at 588 nm was reduced by the degraded N-bond linkages, as well as the formation of degrading products were observed by Fourier transform infrared (FTIR). These results suggest that crystal violet was biodegraded to N,N-dimethylaminophenol and Michler's Ketone prior to these intermediates being further degraded.
Ecotoxicology and Environmental Safety 07/2012; 83:108-14. · 2.29 Impact Factor
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ABSTRACT: Paracoccus sp. strain YF1 immobilized on bamboo carbon was developed for the denitrification. The results show that denitrification was significantly improved using immobilized cells compared to that of free cells, where denitrification time decreased from 24h (free cells) to 15 h (immobilized cells). The efficiency of denitrification increased from 4.57 mg/(Lh) (free cells) to 6.82 mg/(Lh) (immobilized cells). Kinetics studies suggest that denitrification by immobilized YF1 cells fitted well to the zero-order model. Scanning electron microscopy (SEM) demonstrated that firstly, the bacteria became stable on the inside and exterior of the bamboo carbon particles and secondly, they formed biofilm after adhesion. Various factors and their influences on biological denitrification were investigated, namely temperature, pH, initial nitrate concentrations and carbon sources. The immobilized cells exhibited more nitrate removal at various conditions compared to free cells since bamboo carbon as a carrier protects cells against changes in environmental conditions. Denitrification using the YF1 immobilized in bamboo carbon was also maintained 99.8% after the tenth cycle reuse, thus demonstrating excellent reusability. Finally, wastewater was treated using the immobilized cells and the outcome was that nitrogen was completely removed by bamboo-immobilized YF1.
Journal of hazardous materials 06/2012; 229-230:419-25. · 4.14 Impact Factor
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ABSTRACT: The degradation of Scarlet 4BS (4BS) in aqueous solution using Fe/Ni nanoparticles was investigated in this paper. Batch experiments show that the degradation of 4BS depended on an initial dye concentration, the solution pH and total Fe/Ni concentration and reaction temperature. The removal of 84.5% of 4BS was achieved when the solution contained 100 mg/L of 4BS under optimal conditions, including an 8.0 g/L nanoscale Fe/Ni, pH 5.0, 30 °C for 3 h. In addition, a kinetics study indicates that the degradation of 4BS was well suited to the pseudo-first-order model, where the apparent rate constant (K(obs)) was 6.3×10(-3) min(-1). Moreover, XRD indicated that no iron and nickel oxide formed after Fe/Ni nanoparticles reacted to 4BS. However, data from FTIR show that new bands appeared which corresponding to CH after 4BS reacted with the Ni/Fe nanoparticles. A degradation mechanism is proposed here where iron was oxidized, the hydrogen being produced was adsorbed on the catalytic nickel surface, 4BS reductively by degrading two cleaving the azo linkages. This application has much potential in that 71.2% of 4BS was removed from wastewater.
Journal of Colloid and Interface Science 06/2012; 381(1):30-5. · 3.07 Impact Factor
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ABSTRACT: Metal ions, in the form of their EDTA complexes, can be separated and determined by ion chromatography coupled to inductively
coupled plasma mass spectrometry (ICP-MS). However, polyatomic interferences can occur during ICP-MS process and this requires
techniques for removing or reducing them. ICP-MS combined with an octopole reaction system was used to reduce polyatomic interferences
during the detection of metal ions (55Mn, 56Fe, 59Co, 60Ni, 63Cu, 64Zn, 208Pb) as their EDTA complexes followed by the separation of IC. The results indicated that polyatomic interferences can be reduced
for the detection of 56Fe, 60Ni, 63Cu and 64Zn if either helium or hydrogen gas was added to the collision/reaction cell. Hydrogen was preferred since it resulted in
higher sensitivity and lower background intensity. The separation of seven metal ions was achieved on an anion-exchange column
within 7min using diammoniumhydrogen phosphate buffer of pH7.5 as the mobile phase. The detection limits were in the range
of 0.1–0.5μgL−1 with the exception of Fe (5.0μgL−1) if hydrogen was the reaction gas. The method was applied to the determination of metal ions in natural water samples.
KeywordsEDTA complexes-IC-ICP-MS-Metal ions-Octopole reaction system-Speciation
Microchimica Acta 04/2012; 169(1):41-47. · 3.03 Impact Factor
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ABSTRACT: Ion-exclusion chromatography (IEC) coupled with electrospray ionization quadrupole mass spectrometry (ESI-MS) has been used
for the analysis of carboxylic acids. The use of ESI-MS provides increased specificity and sensitivity compared to existing
detection methods. This paper applies IEC-ESI-MS to the analysis of carboxylic acids in commonly found root exudates and shows
that the separation of nine carboxylic acids (pyruvic, oxalic, lactic, malonic, maleic, succinic, tartaric, aconitic and citric
acids) can be achieved by IEC within 8min. The ESI provided reasonable signals from negative ions, [M−H]− in the negative ionization mode. Linear plots of peak area versus concentration were obtained in the range 50–25,000μgL−1 for MS detection under optimized MS conditions. The detection limits of target organic acids, based upon signal to noise
ratio (S/N=3), ranged from 10 to 30μgL−1. The reproducibility of peak areas was <2.5% (n=5). The proposed method was used for the confirmation and quantification of carboxylic acids in nutrient solutions containing
root exudates.
Chromatographia 04/2012; 67(1):113-117. · 1.20 Impact Factor
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ABSTRACT: In this study, a rapid, sensitive, and fully automated on-line solid phase extraction (SPE)–liquid chromatography (LC)–mass
spectrometry (MS) method for the analysis of explosive residues in water, was systematically investigated. First, separation
of explosive residues was achieved by reverse-phase chromatography using an XDB-C18 column in 30min with an eluent containing
0.1% acetic acid, 5mM ammonium acetate, and methanol. Secondly, atmospheric pressures chemical ionization (APCI) and electrospray
ionization (ESI) interfaced with the MS detector were used to examine the explosive residues, indicating that APCI–MS was
more suitable than ESI–MS for the detection of explosives. Thirdly, the conditions for on-line SPE, including solvent pH and
sample injected volume, were optimized. The calibration curves obtained for all explosives studied were linear in the concentration
range 0.5–50μgL−1. The detection limits of this method ranged from 0.05 to 0.5μgL−1 when 4000μL of sample was on-line pre-concentrated on C18 enrichment column. The recoveries from lake waters spiked with
explosive standard solution ranged from 90.5 to 108.0%. The proposed method is simple, fast, and could be applied successfully
to the analysis of explosive residues in contaminated water without any further pretreatment.
KeywordsColumn liquid chromatography–Atmospheric pressure chemical ionization-mass spectrometry–On-line solid phase extraction–Explosives–Water
Chromatographia 04/2012; 73(7):631-637. · 1.20 Impact Factor
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ABSTRACT: Zero-valent iron (ZVI) nanoparticles tend to agglomerate, resulting in a significant loss in reactivity. To address this issue, synthesized bentonite-supported nanoscale zero-valent iron (B-nZVI) was used to remove azo dye methyl orange (MO) in aqueous solution. Batch experiments show that various parameters, such as pH, initial concentration of MO, dosage, and temperature, were affected by the removal of MO. Scanning electron microscopy (SEM) confirmed that B-nZVI increased their reactivity and a decrease occurred in the aggregation of iron nanoparticles for the presence of bentonite (B). Using B-nZVI, 79.46% of MO was removed, whereas only 40.03% when using nZVI after reacting for 10 min with an initial MO concentration of 100 mg/L (pH=6.5). Furthermore, after B-nZVI reacted to MO, XRD indicated that iron oxides were formed. FTIR showed that no new bands appeared, and UV-vis demonstrated that the absorption peak of MO was degraded. Kinetics studies showed that the degradation of MO fitted well to the pseudo first-order model. A degradation mechanism is proposed, including the following: oxidation of iron, adsorption of MO to B-nZVI, formation of Fe(II)-dye complex, and cleavage of azo bond. Finally, the removal rate of MO from actual wastewater was 99.75% when utilizing B-nZVI.
Journal of Colloid and Interface Science 08/2011; 363(2):601-7. · 3.07 Impact Factor
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ABSTRACT: Edible marine products (n=24) collected from the fish markets in Adelaide, Australia, were analysed for the presence of polybrominated diphenyl ethers (PBDEs). The total concentration of 11 PBDE congeners found in the marine products ranged from 1.01 to 45 ng/g fresh weight. Among the samples analysed, imported silver fish and prawns from Vietnam and Thailand respectively, recorded the highest ∑PBDEs concentrations (45.10 and 43.29 ng/g fresh weight) as against 13.08 and 12.57 ng/g fresh weight in Australian king prawns and Gar fish. BDE-209 was the most dominant congener in the marine products followed by BDE-47, 99 and 100. The calculated average daily intakes of ∑PBDEs per day for an adult male and female (19 or more years old) were 1026.8 and 1188.4 ng/kg per day, respectively. This study clearly shows that the dietary exposure to marine foods can contribute to PBDEs accumulation in human body.
Marine pollution bulletin 06/2011; 63(5-12):154-9. · 2.63 Impact Factor
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Journal of Liquid Chromatography & Related Technologies 05/2011; · 0.71 Impact Factor
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ABSTRACT: The use of nanoscale zero-valent iron (nZVI) to remediate contaminated groundwater is limited due to its lack of durability and mechanical strength. To address this issue, 20% (w/w) nZVI was loaded onto kaolinite as a support material (K-nZVI). More than 96% of Pb(2+) was removed from aqueous solution using K-nZVI at an initial condition of 500 mg/L Pb(2+) within 30 min under the conditions of 10 g/L of K-nZVI, pH 5.10 and a temperature of 30 °C. To understand the mechanism of removal of Pb(2+), various techniques were implemented to characterize K-nZVI. Scanning electron microscopy (SEM) indicated that K-nZVI had a suitable dispersive state with a lower aggregation, where the mean specific surface area and average particle size as determined by the BET-N(2) method and X-ray diffraction (XRD), were 26.11 m(2)/g and 44.3 nm, respectively. The results obtained from XRD, X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared (FTIR) indicated that a small number of iron oxides formed on the surface of K-nZVI, suggesting that free Pb(2+) was adsorbed onto K-nZVI and subsequently reduced to Pb(0).
Water Research 05/2011; 45(11):3481-8. · 4.86 Impact Factor
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ABSTRACT: On-line solid-phase extraction (SPE) for pre-concentration and sample cleanup is one strategy to reduce matrix effects and to simultaneously improve detection sensitivity in liquid chromatography/mass spectrometry (LC/MS). This paper describes an on-line SPE-LC/MS method for the determination of tributyltin (TBT) and triphenyltin (TPhT) at trace levels in water samples. The direct coupling of an on-line C18 pre-column to LC/MS was used to pre-concentrate TBT and TPhT at trace levels from waters and to remove interfering matrix effects. Pre-concentration was followed by separation of TBT and TPhT on a C18 column using a mobile phase containing 0.1% (v/v) HCOOH/5 mM HCOONH4 and methanol. While both electrospray ionization (ESI) and atmospheric pressure chemical ionization (APCI) can be interfaced with MS for the detection of TBT and TPhT, ESI-MS was preferred for this application. The calibration curve for the targets was linear in the concentration range 0.1-30 microg L(-1). The detection limit (signal-to-noise (S/N) ratio = 3) was 0.02 microg L(-1) when 3.0 mL of sample was enriched on the C18 pre-column. The recoveries of TBT and TPhT in spiked waters were from 81.0 to 101.9%. The reproducibilities for the analysis of the standard mixture (10 microg L(-1)) for TBT and TPhT were 13.1 and 5.0%, respectively. The developed method was an easy and fast way to analyze TBT and TPhT in water samples.
Rapid Communications in Mass Spectrometry 11/2009; 23(23):3795-802. · 2.79 Impact Factor
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ABSTRACT: Ion-pairing chromatography coupled with inductively coupled plasma mass spectrometry (ICP-MS) used for the speciation of phosphorus is limited as the mobile phase containing organic solvents changes in detection sensitivity and the carbon precipitates on torch and cones. To address this issue, anion-exchange chromatography with ICP-MS has been used for the speciation of glyphosate, phosphate and aminomethylphosphonic acid in soil extracts. The separation of the targets on a new column was achieved within 5 min using an eluent containing 20 mM NH(4)NO(3) at pH 5.1. Furthermore, since the polyatomic ions such as (14)N(16)O(1)H(+) and (15)N(16)O(+) from a nitrogen-based ion-pairing reagent interfered with ICP-MS detection of (31)P, an octopole reaction system was investigated to determine whether the polyatomic interferences could be reduced. The results show that addition of He to the cell can benefit analyses by reducing such interferences, but at the expense of reduced sensitivity. The detection limits in the range of 1.0-1.5 microg L(-1) (expressed as P) was achieved when 50 microL was injected using He as the collusion gas.
Talanta 06/2009; 78(3):852-6. · 3.79 Impact Factor
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ABSTRACT: This report describes the extraction of selenium species contained in pharmaceutical tablets using either enzymatic hydrolysis
or sodium dodecyl sulphate extraction (SDS). The selenium species were determined by ion chromatography coupled to inductively
coupled plasma mass spectrometry. In the enzymatic extraction approach, proteolytic enzymes (protease/lipase) were used in
a buffer containing 75mM Tris–HCl at pH 7.5. It was found that the extraction efficiency was significantly improved relative
to the use of the SDS approach. For example, the extraction recovery was more than 80% of total Se, where selenocystine Se-methyl-selenocysteine
(SeMC) and selenomethionine (SeMet) in the samples were extracted. In contrast, chemical extraction of Se using SDS gave only
60% of total Se, while only two species, SeMC and SeMet, were found. In addition, SeMC was found to be unstable and degraded
through oxidation in the extraction solution. Finally, the two enzyme methods were applied to commercial pharmaceutical tablets.
Microchimica Acta 03/2009; 165(1):167-172. · 3.03 Impact Factor
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ABSTRACT: We have developed a novel microwave-assisted extraction method for determining the arsenic (As) speciation in soils that is based on extraction with phosphate solutions, including orthophosphoric acid, ammonium dihydrogen orthophosphate, and ammonium hydrogen orthophosphate. The highest extracting efficiency was obtained with 1 M ortho-phosphoric acid solution as the extractant, and this efficiency is associated with the pH of the extractant. Total As content and As species in the soil extracts were determined by inductively coupled plasma mass spectrometry (ICP-MS) alone and by the combined ion chromatography (IC) with ICP-MS, respectively. The proposed extraction procedure was applied to National Institute of Standards and Technology (NIST) standard reference material (SRM) 2711 (Montana soil) as well as to environmental soil samples collected from the agricultural lands of Bangladesh. As(V) was detected in all the soil samples, and As(III) was detected in nine soils of the 20. These results of extractable As testing indicate that the extraction of As species mainly depends on the composition of the soils. The As speciation results also indicate that As adsorption is highly dependent on the iron, aluminum, and manganese concentrations in the soil. The stability of As species in the extracts was also studied.
Environmental Geochemistry and Health 01/2009; 31 Suppl 1:93-102. · 1.62 Impact Factor
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ABSTRACT: The speciation of Zn-aminopolycarboxylic complexes was investigated using both electrospray ionization mass spectrometry (ESI-MS) and ion chromatography (IC) with inductively coupled plasma mass spectrometry (ICP-MS). The resulting ESI mass spectra indicated that [Zn(HEDTA)](1-), [Zn(NTA)](1-), [Zn(EDTA)](2-) and [Zn(DTPA)](3-) were all simultaneously detected in solution; [Zn(NTA)](1-) exhibited the weakest intensity of all these Zn-aminopolycarboxylic complexes. IC/ICP-MS was also successfully used to separate Zn complexes by anion-exchange chromatography using a mobile phase containing 30 mM (NH(4))(2)HPO(4) at pH 7.5 giving reasonable resolution within 15 min. A weak peak attributable to the poor stability [Zn(NTA)](1-) ion was also observed using IC/ICP-MS. With the exception of [Zn(NTA)](1-), detection limits ranging from 0.5 to 1.0 microg/L were obtained and the proposed method was used for the determination of Zn aminopolycarboxylic complexes in soil solution.
Rapid Communications in Mass Spectrometry 01/2009; 23(3):419-24. · 2.79 Impact Factor
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ABSTRACT: There is still no reliable standard extraction method for the speciation of arsenic (As) in plant tissue, and hence there is great interest in developing one for plants that are used as human food. Speciation and bioavailability are critical for accurate human health risk assessment, as As species vary in both their toxicity and bioavailability. Recent incidences of As poisoning in many countries have led to significant research into the fate and dynamics of As in the soil and water environment, including speciation. Although one of the major pathways of ingestion of As is via food, only limited research has been conducted to assess the nature and proportion of various As species present in food crops. In this study, we compared the efficacy of ammonium dihydrogen phosphate and protein extracting solution for the extractability of As from two different species of spinach (amaranth and silverbeet). We found that a microwave-assisted technique with protein extracting solution was most effective, yielding 76-114% extractability and excellent separation and speciation of all As species present in the spinach matrices. The stability test for extracted As species showed them as stable for 45 days without any significant loss or inter-conversion. Both As(III) and As(V) were identified in the shoots of amaranth and silverbeet. However, the percentage of As species varied between amaranth and silverbeet. The silverbeet shoot showed a somewhat higher percentage of As(V), while the amaranth showed a higher percentage of As(III). The samples contained mostly inorganic As, especially As(III) (>90%) in the edible part of the vegetables, a form that is more toxic and bioavailable than other organic and methylated species.
Environmental Geochemistry and Health 01/2009; 31 Suppl 1:103-13. · 1.62 Impact Factor
