Use Of EDTA Research Articles

Evaluation of the surface free energy on root canal dentine walls treated with chelating agents and NaOCl

To evaluate ex vivo the effects of combined and single use of EDTA, RC-Prep and NaOCl on the surface free energy of canal wall dentine using the captive bubble technique. Eighteen extracted human pre-molar teeth were sectioned at the crown and the apical third, the remaining mid-root portion were bisected longitudinally. Thereafter, the root halves were embedded in resin blocks that exposed the dentine surface of the canal wall. The specimens were randomly assigned to six experimental groups (n = 6) after polishing. The root dentine surfaces of the first two groups were treated with 17% EDTA or RC-Prep followed by 2.5% NaOCl irrigation. Groups 3, 4 and 5 were treated with either 17% EDTA, RC-Prep or 2.5% NaOCl alone. Control specimens were irrigated with saline solution. The surface free energies of experimental groups were calculated by measuring air and octane contact angles on the canal wall dentine. Statistical analysis was performed using the Mann-Whitney U and Bonferroni post-tests at P = 0.05. Compared with the control group; combined and single use of EDTA, RC-Prep and NaOCl irrigation significantly decreased the surface free energy of canal wall dentine surfaces (P < 0.05). Among all groups tested, the use of NaOCl as a final flush following RC-Prep treatment yielded increased wettability. Nevertheless, this value remained lower than that of the control group. Use of chelating agents alone or in combination with NaOCl decreased the wettability of root canal wall dentine.

Reduction of Escherichia coli population following treatment with bacteriocins from lactic acid bacteria and chelators

The inhibitory activity of lactocin 705/AL705 (2133 arbitrary units per ml (AU ml −1)), two bacteriocins produced by Lactobacillus curvatus CRL705 and nisin (1066 AU ml −1) produced by Lactococcus lactis CRL1109 in combination with chelating agents against Escherichia coli strains in TSB medium at 21 and 6 °C was investigated. Treatment with EDTA (500 and 1000 m m) and Na lactate (800 m m) alone produced a variable effect depending on the strain, Na lactate being inhibitory against E. coli NCTC12900 at both assayed temperatures while EDTA (1000 m m) led to its inactivation only at 6 °C. Direct and deferred strategies using EDTA and Na lactate showed that the direct addition of bacteriocins and chelators was not as effective as compared to deferred treatments. When the deferred treatment effectiveness was evaluated at 6 °C, the use of EDTA (500 and 1000 m m) and Na lactate (800 m m) in combination with lactocin 705/AL705 demonstrated to be the most inhibitory strategy against both E. coli strains. Nevertheless, treatments with chelators and bacteriocins was highly dependent upon strain sensitivity. Permeabilization of the outer membrane of E. coli strains with EDTA and Na lactate combined with lactocin 705/AL705 showed to be valuable in controlling this foodborne bacteria at low temperatures.

Phytoextraction: a review on enhanced metal availability and plant accumulation

Phytoextraction has emerged as a novel approach to clean up metal-polluted soils in which plants are used to transfer toxic metals from soils to shoots. This review provides a synthesis of current knowledge on phytoextraction of metals from soils and their accumulation in plants. The objective is to integrate soil-related (root exudates and chemical amendments) and biological advances to suggest research needs and future directions. As far as can be deduced from the literature, it will be some time before phytoextraction may be established as a commercial technology. For chemically-assisted phytoextraction, research has not shown easily biodegradable compounds to overcome the risks associated with the use of EDTA for poorly available metals in soils. On the other hand, significant progress has been made on the physiological and molecular aspects regarding tolerance and phytoaccumulation of metals in plants. A multidisciplinary approach is warranted to make phytoextraction a feasible commercial technology to remediate metal-polluted soils.

Nursery Protocols for the Rearing of the Brown Shrimp, Farfantepenaeus aztecus

Recreational saltwater fishing in coastal areas of the United States of America is partly dependent on the availability of live bait for anglers. One bait species commonly used is the brown shrimp, Farfantepenaeus aztecus. Three experiments were conducted with eight-day-old post-larvae (PL8) to evaluate the effects of stocking density and water salinity on survival, growth, and feed conversion ratio (FCR) of F. aztecusin nurseries. In the first experiment, the effects of stocking density were evaluated for a period of 11 days. Post-larvae (PL) were stocked into round tanks (760 L) at densities of 30, 40, 50, and 60 PL/L with four replicates per treatment. There were no significant differences (P > 0.05) in final mean weight, survival, and estimated FCR among treatments. In the second experiment, shrimp were stocked into 159-L square polyethylene tanks at four densities (1.0, 1.9, 7.9, and 13 PL/L) and maintained for 12 days. Shrimp reared at low densities grew significantly larger and had significantly lower FCR than those stocked at higher densities. There were no significant differences in survival. In the third experiment, PL were stocked at two salinities (16 ppt and 32 ppt) with six replicates per salinity. Three of the tanks at each salinity were then treated with EDTA (3 ppm). Fourteen days after the start of the experiment, sub-samples of shrimp from each treatment were weighed and returned to the tanks. Salinity in the 32 ppt treatment was then gradually decreased to 16 ppt during a 24-hour period and the shrimp reared for an additional seven days. There were significant differences in mean weights among treatments at the end of the 14 day grow-out period (32 ppt, 10.1 mg; 16 ppt, 7.2 mg). At the end of the experiment, the use of EDTA did not seem to have an effect on production. However, shrimp subjected to late acclimation to the lower salinity were significantly smaller than those acclimated at stocking (11.8 mg vs. 21.2 mg). This reduced weight is presumably due to acclimation stress resulting in a lag in growth. The high salinity treatment resulted in significantly higher survival (32 ppt, 51.3%; 16 ppt, 44.4%), while the FCR was significantly lower (32 ppt, 1.75; 16 ppt, 2.08). Present results indicate that nursery systems, if properly utilized and correctly managed, could assist in the development of a viable bait-shrimp aquaculture industry.

Interaction between EDTA and Sodium Hypochlorite: A Nuclear Magnetic Resonance Analysis

Recent studies detected erosion of the dentinal walls following the use of EDTA as a final flush. Several authors have studied degradation of EDTA and it appears to be caused by an oxidation reaction. The objective of this paper was to verify through nuclear magnetic resonance (NMR) analysis if the oxidizing property of sodium hypochlorite inactivates EDTA. Solutions of sodium hypochlorite and EDTA were analyzed. EDTA tracing and the appearance of new signals indicative of by-products of the reaction, were studied at different time intervals with a NMR analysis. The tracings of NMR analysis confirmed that the reaction between sodium hypochlorite and EDTA lead to a very slow but progressive degradation of this compound. Mindful of the limitations of an in vitro study, the results of this study nevertheless demonstrated that a final flush with sodium hypochlorite cannot limit the chelating effects of EDTA in a clinically realistic time period.

Equilibrium and NMR studies on GdIII, YIII, CuIIand ZnIIcomplexes of various DTPA–N,N″-bis(amide) ligands. Kinetic stabilities of the gadolinium(iii) complexes

Three DTPA-derivative ligands, the non-substituted DTPA-bis(amide) (L(0)), the mono-substituted DTPA-bis(n-butylamide) (L(1)) and the di-substituted DTPA-bis[bis(n-butylamide)] (L(2)) were synthesized. The stability constants of their Gd3+ complexes (GdL) have been determined by pH-potentiometry with the use of EDTA or DTPA as competing ligands. The endogenous Cu2+ and Zn2+ ions form ML, MHL and M(2)L species. For the complexes CuL(0) and CuL(1) the dissociation of the amide hydrogens (CuLH(-1)) has also been detected. The stability constants of complexes formed with Gd3+, Cu2+ and Zn2+ increase with an increase in the number of butyl substituents in the order ML(0) < ML(1) < ML(2). NMR studies of the diamagnetic YL(0) show the presence of four diastereomers formed by changing the chirality of the terminal nitrogens of their enantiomers. At 323 K, the enantiomerization process, involving the racemization of central nitrogen, falls into the fast exchange range. By the assignment and interpretation of 1H and 13C NMR spectra, the fractions of the diastereomers were found to be equal at pH = 5.8 for YL(0). The kinetic stabilities of GdL(0), GdL(1) and GdL(2) have been characterized by the rates of the exchange reactions occurring between the complexes and Eu3+, Cu2+ or Zn2+. The rates of reaction with Eu3+ are independent of the [Eu3+] and increase with increasing [H+], indicating the rate determining role of the proton assisted dissociation of complexes. The rates of reaction with Cu2+ and Zn2+ increase with rising metal ion concentration, which shows that the exchange can take place with direct attack of Cu2+ or Zn2+ on the complex, via the formation of a dinuclear intermediate. The rates of the proton, Cu2+ and Zn2+ assisted dissociation of Gd3+ complexes decrease with increasing number of the n-butyl substituents, which is presumably the result of steric hindrance hampering the formation or dissociation of the intermediates. The kinetic stabilities of GdL(0) and GdL(1) at pH = 7.4, [Cu2+] = 1 x 10(-6) M and [Zn(2+)] = 1 x 10(-5) M are similar to that of Gd(DTPA)2-, while the complex GdL2 possesses a much higher kinetic stability.

Effectiveness of NaOCl alone or in combination with EDTA on the diffusion of hydroxyl ions released by calcium hydroxide paste

Aim:To evaluate the effect of different irrigant solutions employed during removal and replacement of calcium hydroxide paste on the diffusion of hydroxyl ions through root canal dentine in vitro.Methodology:Thirty-five maxillary and mandibular human canines with straight and fully developed roots were used. After mechanical preparation up to 1mm short of tooth length, 30 canals were filled with calcium hydroxide paste and 5 canals were left empty; all teeth had their coronal accesses properly sealed. Teeth were placed in plastic containers with distilled water, and pH was read after 30 days when the paste from 20 teeth was renewed. After removal of the paste by endodontic instrumentation and irrigation with distilled water, canals were replenished with newly mixed paste in Group 1 and 2. In these groups, final irrigation was conducted with 5 mL of EDTA followed by 5 mL of NaOCl in specimens in Group 1, and 5 mL of NaOCl only in specimens in Group 2. In 10 teeth the paste was not replenished at 30 days (Group 3). All specimens were returned to the containers with fresh distilled water, and the pH was recorded after another 30 days. The differences between the first (30d) and second (60d) pH readings were calculated and submitted to analysis of variance and individual comparisons using the Scheffeé's test.Results:Results of mean analysis on differences of pH readings showed that greater diffusion had occurred on specimens in Group 3. Individual comparisons using Scheffeé's test showed statistical significance between Groups 2 and 3, and equivalence between all other groups.Conclusion:It was concluded that the use of EDTA did not enhance diffusion of hydroxyl ions through root canal dentine.

Preservation strategies for inorganic arsenic species in high iron, low-Eh groundwater from West Bengal, India

Despite the importance of accurately determining inorganic arsenic speciation in natural waters to predicting bioavailability and environmental and health impacts, there remains considerable debate about the most appropriate species preservation strategies to adopt. In particular, the high-iron, low-Eh (redox potential) shallow groundwaters in West Bengal, Bangladesh and SE Asia, the use of which for drinking and irrigation purposes has led to massive international concerns for human health, are particularly prone to changes in arsenic speciation after sampling. The effectiveness of HCl and EDTA preservation strategies has been compared and used on variably arsenic-rich West Bengali groundwater samples, analysed by ion chromatography-inductively coupled plasma-mass spectrometry (IC-ICP-MS). Immediate filtration and acidification with HCl followed by refrigerated storage was found to be the most effective strategy for minimizing the oxidation of inorganic As(III) during storage. The use of a PRP-X100 (Hamilton) column with a 20 mmol L(-1) NH4H2PO4 as mobile phase enabled the separation of Cl- from As(III), monomethylarsonic acid, dimethylarsinic acid and As(V), thereby eliminating any isobaric interference between 40Ar35Cl+ and 75As+. The use of EDTA as a preservative, whose action is impaired by the high calcium concentrations typical of these types of groundwater, resulted in marked oxidation during storage. The use of HCl is therefore indicated for analytical methods in which chloride-rich matrices are not problematical. The groundwaters analysed by IC-ICP-MS were found to contain between 5 and 770 ng As mL(-1) exclusively as inorganic arsenic species. As(III)/total-As varied between 0 and 0.94.

Phytoremediation of lead using Indian mustard ( Brassica juncea) with EDTA and electrodics

The use of plants to remove toxic metals from soil (phytoremediation) is emerging as a cost-effective alternative to conventional methods. Because contaminants such as lead have limited bioavailability in the soil, methods to facilitate its transport to the shoots and roots of plants are required to the success of phytoremediation. Indian mustard ( Brassica juncea) has been shown to be effective at accumulating high tissue concentrations of lead when grown in contaminated soil with the addition of a chelating agent, such as EDTA. The addition of an electric field around the plants is an alternative approach to increase the uptake of lead. In this work, bench scale studies illustrated the application of electrodic phytoremediation with EDTA for lead using Indian mustard. The effects of a range of parameters such as operating current/voltage with different concentrations, application time of EDTA and electric potential, and daily application time of electric potential were studied. The accumulation of lead in the shoots using 0.5 mmol/kg EDTA with electric potential increased by two- to four-fold compared to the use of EDTA only. The maximum lead accumulation in the shoots was obtained with the application of electric field 1 h per day for 9 days with EDTA.

Effects of EDTA on signal stability during electrochemical detection of acetaminophen

The use of EDTA in the medium to avoid the passivation of a solid electrode during electrochemical analysis of acetaminophen is presented in this work. The performance of this system was investigated with respect to pH, applied potential and supporting electrolyte concentration. The major advantage in using EDTA in the supporting electrolyte is the significant increase in sensitivity, precision and stability of the measurements, when compared to the system in absence of the chelating agent. The sensitivity increases 5.5 times (21.5 and 3.9mAlmol−1 in the presence and the absence of EDTA, respectively), the repeatability (n=20) is 3.5 times better, expressed by within-run-precision of 4.0% for 6.0×10−5moll−1 acetaminophen in the presence of EDTA while, in its absence, the within-run-precision was higher than 14%. Moreover, the system showed excellent stability, allowing more than 120 measurements with no significant changes.

Phytoremediation of metals contaminated dredged sediments: Use of synthetic chelates in metals phytoextraction

The waterways maintenance leads to a large volume of dredged polluted sediments, to be disposed of, every year. As the economic disposal of dredged sediment is a single line along the stream, they can behave as a sink of pollutant and a migration in the environment is observed. Chelate-enhanced phytoremediation has been proposed as an effective tool for the extraction of heavy metals from dredged sediment by plants. Lysimeters studies were conducted to study the phytoremediation of sediments with EDTA and lactic acid used as synthetic chelators. EDTA appeared to enhance metal solubility but plant uptake did not increase accordingly. Furthermore EDTA enhance metal leaching which could lead to groundwater pollution. To prevent these unwanted side-effects, careful management of phytoremediation and of the use of EDTA seems necessary.

Recombinant Plasmodium falciparum NADP-dependent isocitrate dehydrogenase is active and harbours a unique 26 amino acid tail

During infection, Plasmodium spp. require reducing equivalents such as NADPH to support the function of specific enzymes in overcoming oxidative stress. The catalysis of isocitrate by the NADP-dependent isocitrate dehydrogenase of Plasmodium falciparum (pfICDH) generates NADPH and is thus crucial for the parasite’s survival and pathogenecity. In this study, pfICDH was cloned from a clinical isolate of P. falciparum. This was facilitated by designing primers based on the P. falciparum genome sequence resource PlasmoDB. DNA sequence of the cloned gene revealed an ORF that encodes a protein of 468 aa. Furthermore, after expression in Esherichia coli BL21, enzyme assays of cell-free extracts confirmed the overexpression and function of pfICDH. Further, pfICDH purified by affinity chromatography retained its enzyme activity. Substitution of NADP for NAD, or the use of EDTA, in enzyme assays abolished pfICDH activity. ATP and chloroquine, as well as cupric and argentic ions, inhibited pfICDH activity. Phylogenetic analysis revealed high primary structure homology (45–97%) among genes coding for eukaryal NADP-dependent ICDH, and the occurrence of three subfamilies of ICDH genes. Interestingly, there were significant sequence dissimilarities between pfICDH and its mammalian or bacterial homologs, particularly at the N- and C-termini. Confirming the functionality of the cloned pfICDH, and asserting its distance from the human homolog by molecular definitions, are important prerequisites for promoting this gene as a drug target screen. Index Descriptors and Abbreviations: ICDH, isocitrate dehydrogenase; pfICDH, Plasmodium falciparum ICDH; NADPH, β-nicotinamide adenine dinucleotide phosphate reduced; NADP, β-nicotinamide adenine dinucleotide; GST, gluthathione- S-transferase; ORF, open-reading frame

Apoenzymes of alkaline phosphatases of different origin for determining of trace zinc(II)

The applicability of the apoenzymes of three alkaline phosphatases of different origin (bacterial from E. coli and animal from chicken intestine or the small intestine of a Greenland seal) to the determination of zinc(II) was studied. The alkaline apophosphatase from seal intestine was found to be promising for this purpose. The preparation conditions of the apoenzyme and the conditions of its reactivation with zinc(II) were optimized. Based on the reactivating effect of zinc(II) on the apoenzyme, which was prepared with the use of EDTA, an enzymatic method was developed for determining zinc(II) (0.01–0.1 μg/mL) with c min = 8 ng/mL. The proposed procedure was applied to the determination of zinc(II) in blood serum.

Lead mobilization during calcium disodium ethylenediaminetetraacetate chelation therapy in treatment of chronic lead poisoning

It has long been established that chronic lead (Pb) poisoning is a cause of renal insufficiency. However, although easily diagnosed, there is still no treatment available that will revert this type of poisoning. We report a study performed on 56 male Wistar rats administered Pb in drinking water (500 ppm Pb acetate) over a 90-day period. Twenty-one non-Pb-exposed animals served as the control group. Seven animals from each group were killed days 60 and 90. At the end of the 90-day period, 21 of the Pb-exposed animals were treated with disodium monocalcium EDTA (50 mg/kg/d for 5 days) intraperitoneally and 21 animals were administered serum saline by the same route. Three treatment courses were administered, separated by 9 days free of treatment. Seven animals from each subgroup were killed at the end of each treatment course. Pb levels were determined in blood, urine, liver, brain, kidney, and bone. Treatment with EDTA led to a greater and more rapid reduction in Pb contents in the brain and kidney. The decrease in hepatic Pb levels in the treated group of animals was similar to that in the group administered placebo. Bone Pb levels also failed to show a response to the chelating agent. Use of EDTA appears to result in a reduction in Pb deposits in such critical organs as the kidney and brain. However, the chelating agent does not seem to have access to bone Pb deposits, such that the skeleton becomes a permanent source of poisoning for other tissues. © 2002 by the National Kidney Foundation, Inc.

Diagnostic leaching of galena and its oxidation products with EDTA

Many authors have used EDTA as a means of determining the extent of oxidation of flotation pulps. However, there have been few documented studies of the reaction mechanisms in the interaction of EDTA with sulphide minerals and their oxidation products. This paper examines the use of EDTA to extract lead oxidation products from galena. In the first instance, it will be demonstrated that all oxygen containing galena oxidation products (i.e. sulphate, hydroxide, oxide, and carbonate, but not polysulphide or sulphur) are rapidly solubilized in EDTA. Secondly, it is shown that EDTA does not extract lead from un-reacted galena. Continued extraction of lead with increasing conditioning time is due to continued galena oxidation, not to the extraction of lead from galena. Argon gas purging minimises this oxidation whereas the use of air or nitrogen gas purging do not. Using information gathered from these experiments, an improved EDTA extraction technique was developed and compared with other techniques used within the mining industry.

Immunoassay by graphite furnace atomic absorption spectrometry using a metal chelate as a label

A new immunoassay method was developed by using graphite furnace atomic absorption spectrometry and EDTA–Cd 2+ chelate as a label. The new approach combined the use of EDTA–Cd 2+ chelate labeled streptavidin (SA), biotinylated antibody or antigen, and graphite furnace atomic absorption detection for both sandwich-type immunoassay and competitive-type immunoassay. The measurements of α-fetoprotein (AFP) in human sera and bensulfuron-methyl (BSM) in water were used as the models to evaluate the usefulness of the method. The assays were carried out with 96-well microtiter plate as solid-phase carrier. After the immune reaction and biotin–streptavidin binding reaction, a solution of 0.2 M HNO 3 was added to each well to dissociate Cd 2+ in the immune complex on the solid-phase into the solution. The antigen concentration, was thus, determined by measuring the Cd 2+ absorbance of the solution with graphite furnace atomic absorption spectrometry. The present method gives detection limits of 0.12 ng ml −1 for AFP and 0.95 ng ml −1 for BSM, respectively. The coefficient variations (CVs) of the method are less than 8.0%, and the recoveries are in the range of 90–110%. The concentrations of AFP in 23 human serum samples were determined, and the results were compared with those of the independently determined by time-resolved fluoroimmunoassay method. A good correlation was obtained with a correlation coefficient of 0.993.

Effects of Chelating Agents and Sodium Hypochlorite on Mineral Content of Root Dentin

Effects of combined and single use of EDTA, RC-Prep, and NaOCl on mineral content of root dentin were evaluated in vitro using energy dispersion spectrometric microanalysis. Thirty-six standardized midroot dentin specimens obtained from human anterior teeth were used. Specimens were polished and divided into six experimental groups. The first two groups were treated with EDTA or RC-Prep followed by NaOCl irrigation. Groups 3 to 5 were treated with EDTA, RC-Prep, and NaOCl, respectively. The last group was irrigated with saline solution as a control. Levels of calcium, phosphorus, and magnesium were measured in the root dentin after treatments. The results showed that (i) EDTA combined with NaOCl irrigation as final flush and NaOCl alone changed the calcium/phosphorus ratio of root dentin significantly (p < 0.05); and (ii) there was a significant increase in the magnesium level after the use of chelating agent combined with NaOCl (p < 0.05). It was concluded that using NaOCl irrigation as final flush altered the effectiveness of chelating agents on root dentin.

Purification and characterisation of a haemorrhagic fraction from the venom of the Uracoan rattlesnake Crotalus vegrandis

Uracoan rattlesnake ( Crotalus vegrandis) venom was subjected to chromatographic, electrophoretic, biochemical and in vivo haemorrhagic analysis. A haemorrhagic toxin (Uracoina-1) active on skin at the site of inoculation in mice was purified by Mono Q2 anion-exchange chromatography and size exclusion (SE) high-performance liquid chromatography. The purified preparation was a protein of M r 58 000 as revealed by sodium dodecyl sulphate–polyacrylamide gel electrophoresis under denatured conditions and with silver staining. The use of EDTA, EGTA and 1,10-phenanthroline inhibited haemorrhagic and proteolytic activities. Inhibitors of serine proteinases such as PMSF and TCLK had no effect on the haemorrhagic fraction. Uracoina-1 hydrolyses casein, hide powder azure and fibrinogen have an optimal pH of 8.2. It rapidly digests the Aα-chain of fibrinogen. Thermal denaturation of Uracoina-1 after exposure at 60°C for 15 min led to inactivation of the haemorrhagic activity. In addition, Uracoina-1 is myotoxic, lacking haemolytic, defibrinating and lethal effects. The N-terminal amino acid sequence (20 residues) was determined.

Speciation and preservation of inorganic arsenic in drinking water sources using EDTA with IC separation and ICP-MS detection.

The native distribution of As(III) and As(v) in drinking water supplies can influence the treatment removal strategy. The stability of As(III) and As(v) in iron-rich drinking waters can be affected by the formation of Fe precipitates (Fe oxides and/or hydroxides designated by "FeOOH"). These precipitates (ppts) can form during the transport of the sample to the laboratory for arsenic speciation analysis. The analysis of the ppt indicates considerable loss of the aqueous arsenic species (As(aq)) to the solid phase "FeOOH" ppt. Studies of laboratory reagent water containing both As(III) and Fe(III) indicate that the resulting "FeOOH" ppt contained a mixture of As(III) and As(v) with near quantitative removal of the As(aq) in 18 hr. The corresponding aqueous fraction after filtration through a 0.45 microm filter was composed primarily of As(v). The formation of "FeOOH" ppt and the loss of As(aq) to the ppt can be virtually eliminated by the use of EDTA, which sequesters the FeIII). Reagent water fortified with Fe(III), As(III) and EDTA produced less than a 1 ppb change in the As(III)aq concentration over 16 d. The EDTA treatment was also tested on three well waters with different native As(III )/As(v) ratios. The native distribution of As(III)/As(v) was stabilized over a period of 10 d with a worst case conversion of As(III) to As(v) of 2 ppb over a 30 d period. All well waters not treated with EDTA had dramatic losses (a factor of 2-5) of As(aq) in less than 1 d. These results indicated that EDTA preservation treatment can be used to preserve As(aq) in waters where the predominant species is the reduced form [As(III)] or in waters which the predominant species is the oxidized form [As(v)]. This preliminary investigation of EDTA to preserve As species in Fe-rich waters indicates stability can be achieved for greater than 14 d.

Microwave assisted extraction for trace element analysis of plant materials by ICP-AES.

Application of microwave assisted extraction for the decomposition and dissolution of plant samples for trace metal determination by ICP-AES was examined. Dried onion, leaves of spinach beet and three reference materials CTA-OTL-1, CTA-VTL-2 and CL-1 were analyzed. Water, EDTA and hydrochloric acid (0.01, 0.10 and 1.0 M, respectively) were used as leaching solutions. The extraction efficiency was investigated by comparison of the results with those obtained after microwave wet digestion. HCl was found to be very suitable for quantitative extraction of B, Ba, Cd, Cu, Mn, Ni, Pb, Sr and Zn from the samples. For reference materials, the measured concentrations are well consistent with the certified values. The use of EDTA led to a complete extraction of B, Cd, Ni, Pb, Sr and Zn. Water was found to be a good leaching solution for boron. For extraction with HCl and EDTA, the RSD values for the concentrations measured were below 8% for most of the elements.