Diethylenetriaminepentaacetic Acid Concentration Research Articles

Experimental investigation and machine learning modeling of diethylenetriaminepentaacetic acid agents in sandstone rock wettability alteration: Implications for enhanced oil recovery processes

Chelating agents have garnered increasing attention due to their unique capabilities in addressing challenges associated with chemical enhanced oil recovery (CEOR) materials. This research investigates the transformative potential of diethylenetriaminepentaacetic acid (DTPA) chelating agent in altering sandstone rock wettability. Wettability and zeta potential measurements were used to assess the impact of crucial factors including DTPA concentration, salinity, and potential determining ions (PDIs) on contact angle and rock surface charges. The findings revealed that there is an optimal level for DTPA concentration and salinity that can shift rock wettability from an oil-wet to strongly water-wet state. Moreover, while PDIs in their natural concentrations had no significant impact on DTPA performance, a threefold increase in their concentration was found to adversely affect DTPA efficacy. After conducting rock wettability tests, two advanced machine learning (ML) techniques, namely Random Forest (RF) and Boosted Regression Tree (BRT), were employed to assess rock/oil contact angle based on the aforementioned factors. Data were collected from 240 experimental datasets of contact angles. The findings indicated that both models performed well, but BRT exhibited exceptional performance. Sensitivity analysis, conducted using the Jackknife method, revealed the order of importance for parameters affecting wettability as follows: PDIs > salinity > time > DTPA concentration.

Combined effects of biochar and biodegradable mulch film on chromium bioavailability and the agronomic characteristics of tobacco

Biochar (BC) and biodegradable mulch film (BMF) are both commonly used means of production in agriculture. In recent years, most studies have focused on the effects of BC or BMF on soil heavy metal pollution, while they have neglected the combined effects. In this study, a pot experiment was conducted to examine the impacts of BMF, BC, and combined BMF and BC (CMB) on the mobility of chromium (Cr) and the agronomic characteristics of flue-cured tobacco. Compared with the control, BMF, BC, and CMB significantly reduced the concentrations of diethylenetriamine pentaacetic acid (DTPA) extractable Cr in soils by 29.07–29.75%, 45.35–48.54%, and 34.21–37.92%, respectively. In comparison to the application of BMF and BC alone, co-application reduced the availability of Cr in soil via increasing the adsorption of soil Cr and soil enzyme activity, which resulted in the decrease of Cr content and bioconcentration factor and in plants. Moreover, the combined application increased the plant height, stem diameter, leaf area, total root area, root tip number, and root activity of tobacco, which leaded to increase in leaf and root biomass by 11.40–67.01% and 23.91–50.74%, respectively. Therefore, the application of CMB can reduce the heavy metal residues in tobacco leaves and improve tobacco yield and quality.

A comprehensive evaluation of the effect of key parameters on the performance of DTPA chelating agent in modifying sandstone surface charge

Despite the positive aspects of low salinity water (LSW), this technique is relatively expensive and unavailable in some countries. Furthermore, potential problems associated with LSW such as scale precipitation in carbonate reservoirs and fine migration in sandstone reservoirs raise concerns. Chelating agents have the ability to chelate metal ions from solution, effectively reducing the salinity of seawater (SW) and mimicking the behavior of LSW. However, they mitigate the challenges associated with LSW injection. This study focuses on how the Diethylenetriaminepentaacetic acid (DTPA) chelating agent performs in modifying rock surface charge. The impact of concentration, brine salinity, potential determining ions (PDIs), oil presence, Fe3+ ions, and solution pH on the effectiveness of DTPA in altering rock surface charge was evaluated. Furthermore, wettability alteration and sand pack flooding tests were conducted to study the effect of DTPA on rock wettability and oil recovery. Results of wettability alteration, zeta potential, sand pack flooding experiments and ion concentration analysis are reported in this paper. The results showed that reducing salinity, increasing DTPA concentration, and raising solution pH changed rock wettability from oil-wetness towards water-wetness. The presence or absence of PDIs in the solution did not affect the performance of DTPA. However, by tripling the concentration of these ions in the solution, the performance of DTPA in changing rock surface charge was impaired. Based on the wettability alteration and zeta potential experiments, 5 wt% DTPA was determined as the optimum concentration. Subsequent flooding experiments revealed that injecting 5 wt% DTPA chelating agents into the sandstone sand pack after SW injection increased oil recovery from 48 % to 68.3 %. The analysis of ion concentrations also revealed a significant increase in the amount of calcium ions during the DTPA flooding, indicating the chelation of metal ions from both rock and solution and improving the wettability conditions.

Comprehensive analysis of the effect of reservoir key parameters on the efficacy of DTPA chelating agent in minimizing interfacial tension and enhanced oil recovery

Chelating agents reduce the salinity of seawater (SW) and mimic low salinity water (LSW) by binding metal ions in the solution and on the rock surface. This process decreases SW dilution costs and prevents scale formation while improving oil recovery without damaging the reservoir. This study investigates the impact of Diethylenetriaminepentaacetic acid (DTPA) chelating agent on the reduction of interfacial tension (IFT) between oil and SW, without the use of additional chemicals. For the first time, we comprehensively analyzed how reservoir key parameters (concentration, salinity, temperature, and pH) affect the performance of DTPA in reducing IFT. Additionally, rock wettability alteration and sand pack flooding experiments were conducted to evaluate the effect of DTPA on rock wettability and oil recovery. The results revealed that increasing the temperature to 75 °C and the concentration of DTPA to 5 wt% resulted in an IFT reduction to less than 1 mN/m, making the oil miscible in the DTPA solution. Salinity studies demonstrated that by increasing the solution salinity up to the optimal level, the IFT of oil/brine decreased. Furthermore, using 5 wt% DTPA solution altered the rock/oil contact angle from 143° (oil-wet) to 23° (strongly water-wet), highlighting the effect of DTPA on rock wettability alteration. Based on these findings, 5 wt% DTPA was selected as the optimal concentration, resulting in an increase in oil recovery up to 20.3% of original oil in place (OOIP) after SW injection. Elemental analysis of DTPA flooding effluent also confirmed the chelation of metal ions from rock and solution.

Dissolution behavior of DTPA-promoted barium slag and synthesis of submicron BaSO4 particles

Barium slag (BS) is a kind of industrial solid waste generated in barium salt production. Barium in BS can be considered as a secondary source as the content of BaO is as high as 34.80%. The main existent forms of barium in BS are BaSO4, BaCO3 and BaSiO3. It is challenging to dissolve BaSO4 using conventional acids and alkalis due to the low solubility. In this study, diethylenetriaminepentaacetic acid (DTPA) was introduced to investigate the dissolution behavior of barium in BS, and the DTPA complex solution was acidified to release barium for submicron BaSO4 products preparation. Leaching tests were carried out at DTPA concentrations of 0.025–0.30 mol/L, liquid solid ratio of 10–100 mL/g, pH of 8.0–13.0, and reaction temperature of 20–80 °C. The leaching efficiency of barium was 78.64% under the conditions of using 0.10 mol/L DTPA solution (pH of 12.0) at 80 °C for 300 min with the liquid solid ratio of 50 mL/g. BaSO4 products were obtained by the addition of H2SO4 to acidify the leachate at pH ranges of 9.0–7.5. Characterization results from X-ray diffraction, scanning electron microscopy, transmission electron microscopy and dynamic light scattering indicated that the BaSO4 products were nearly sphere particles with the average diameter of 300–500 nm. This work demonstrates that DTPA can dissolve barium in BS and acidifying Ba-DTPA leachate can dissociate barium ions. Furthermore, barium source in BS can be recovered in the form of submicron BaSO4 products through DTPA complexation and decomplexation process.

Effects of Phosphate, Red Mud, and Biochar on As, Cd, and Cu Immobilization and Enzymatic Activity in a Co-Contaminated Soil

Arsenic (As), cadmium (Cd), and copper (Cu) are the primary inorganic pollutants commonly found in contaminated soils. The simultaneous stabilization of the three elements is a preferred approach for mixture-contaminated soils which has received extensive research attention. However, few studies have focused on the immobilization efficiency of a single amendment on the three elements. In this study, phosphate, red mud, and biochar were used to remediate As (237.8 mg kg−1), Cd (28.72 mg kg−1), and Cu (366.5 mg kg−1) co-contaminated soil using a 180-day incubation study. The BCR (European Community Bureau of Reference) extraction method, NH4H2PO4–extractable As, and diethylenetriamine penta-acetic acid (DTPA)–extractable Cd and Cu were analyzed at different time intervals. The results indicated that the application of red mud and biochar significantly reduced soil DTPA–Cd and Cu concentrations during the incubation, while the decrease in soil NH4H2PO4–As was much less than that of soil DTPA–Cd and Cu. After 180 days of incubation, the concentrations of NH4H2PO4–As in red mud and biochar treatments decreased by 2.15~7.89% and 3.01~9.63%, respectively. Unlike red mud and biochar, phosphate significantly reduced the concentration of soil DTPA–Cd and Cu, but failed to lower that of As. The BCR extraction method confirmed that red mud and biochar addition increased the reducible fraction of As due to the surface complexes of As with Fe oxide. Canonical correspondence analysis (CCA) demonstrated that soil pH in addition to available As, Cd, and Cu concentrations were the primary factors in driving the changes in soil enzymatic activity. Soil pH showed positive correlation with soil urease and catalase activities, while negative correlation was observed between soil-available As, Cd, and Cu, and soil enzyme activities. This study revealed that it is difficult to simultaneously and significantly reduce the bioavailabilities of soil As, Cd, and Cu using one amendment. Further research on modifying these amendments or applying combined amendments will be conducted, in order to develop an efficient method for simultaneously immobilizing As, Cd, and Cu.

Dissolution kinetics and solubility of copper oxide nanoparticles as affected by soil properties and aging time.

Nano copper oxide (CuO NP) was added to eight soils to study the effect of aging time of copper on the concentration of diethylenetriaminepentaacetic acid (DTPA)-extracted copper (DTPA-Cu), with bulk copper oxide (CuO BP) and copper nitrate [Cu(NO3)2] used for comparison. Moreover, the effect of soil properties on the dissolution of CuO NP was studied. A dissolution model was used to quantitatively describe the dissolution kinetics of CuO NPs in different soils. The results showed that the concentration of DTPA-Cu decreased with increasing aging time in soils spiked with Cu(NO3)2, while the concentration increased to varying degrees in soils spiked with CuO NPs or CuO BPs. In acidic soils, the equilibrium concentrations of DTPA-Cu were 93.3-98.7mg·kg-1 for CuO NP treatments, 65.5-94.3mg·kg-1 for CuO BP treatments, and 81.4-90.0mg·kg-1 for Cu(NO3)2 treatments, which were greater than those in alkaline soils (43.4-56.9mg·kg-1, 6.26-8.61mg·kg-1, and 73.9-80.0mg·kg-1, respectively). In acidic soils, DTPA-Cu equilibrium concentration ranked the different forms of copper treatments as CuO NPs > Cu(NO3)2 > CuO BPs, while in alkaline soils, the order was Cu(NO3)2 > CuO NPs > CuO BPs. The dissolution rate constants and solubility of CuO NPs were 0.33-6.42 and 37.1-100.1mg·kg-1, respectively. Pearson correlation analysis indicated that the dissolution parameters of CuO NPs were negatively correlated with soil pH and positively correlated with the contents of organic matter, clay, iron oxides, and aluminum oxides. Further, the dissolution rate constant and solubility of CuO NPs could be well predicted by soil pH and the content of free or amorphous aluminum. Our study identified the main factors controlling the dissolution of CuO NPs in farmland soils and highlighted the higher availability of CuO NPs in acidic soils.

Carbonized Apple Branches Decrease the Accumulation and Damage of Cadmium on Apple Rootstock by Reducing DTPA-Cd in Soil

To explore the effects of carbonized apple branches on cadmium(Cd) accumulation and its damage to apple rootstock, the rootstocks of apple(Malus hupehensis Rehd.) in pots containing soil together with 0.5% and 1%(ω) carbonized apple branches were irrigated by a nutrient solution containing CdSO4. The content of DTPA-Cd(cadmium extracted by diethylenetriamine pentaacetic acid) in the potting soil, and the accumulation of Cd in the roots, stems, and leaves of apple rootstocks, were subsequently monitored. The activities of antioxidant enzymes in roots and leaves, root cell death, and the net photosynthesis rate were further analyzed. The results showed that the concentration of DTPA-Cd in the potting soil with carbonized apple branches was significantly lower than that without carbonized apple branches(Cd-only). Compared with the Cd-only treatment, the concentration of DTPA-Cd in the potting soil decreased by 17.50% and 25.55% in the treatment with 0.5% and 1%(ω) carbonized apple branches for 12 days. The Cd accumulation in roots, stems, and leaves; the accumulations of superoxide anions(·O2-), hydrogen peroxide(H2O2), and malondialdehyde(MDA) in roots and leaves; and the amount of cell death in the roots of apple rootstock treated by carbonized apple branches were significantly lower compared to the Cd-only treatment. However, the activities of superoxide dismutase(SOD), peroxidase(POD), and catalase(CAT) in the roots and leaves, and the net photosynthesis rate of apple rootstock treated by carbonized apple branches, were significantly higher than under the Cd-only treatment. Compared with the Cd-only treatment, Cd accumulation in roots decreased by 29.49% and 37.18% in the treatment with 0.5% and 1%(ω) carbonized apple branches for 12 days, and the amount of cell death decreased by 22.73% and 29.09%, respectively. Our results show that carbonized apple branches reduce the uptake and accumulation of Cd in apple rootstock by reducing the content of DTPA-Cd in the soil, thereby alleviating the damaging effect of Cd on cells and photosynthesis. Moreover, the use of 1%(ω) carbonized apple branches was more effective than 0.5%(ω).

Elimination of Diethylenetriaminepentaacetic Acid from Effluents from Pharmaceutical Production by Ozonation

ABSTRACT During production of diethylenetriaminepentaacetic acid (DTPA), process waste water is generated in several production stages. Process wastewater is usually disposed of via waste water treatment plants. However, due to low biodegradability of DTPA in conventional waste water treatment, incineration constitutes the current method of choice. The main disadvantage of incineration is high consumption of primary energy sources leading to substantial emission of carbon dioxide (CO2). Thus, an alternative method of process waste water treatment was investigated, which consists of an initial application of ozone and a subsequent biological treatment. In 2009, preliminary laboratory experiments were conducted to evaluate the elimination of DTPA in process waste water. Based on the initial results, the responsible authorities granted approval for large-scale ozonation of DTPA-containing wastewater in 2011. Additional laboratory scale experiments were carried out to assess the elimination of the target compound and the generation of its main transformation products using liquid chromatography – high resolution mass spectrometry. Through application of the postulated method, the concentration of DTPA and its derivatives can be reduced to levels assuring safe discharge into the receiving water. Additionally, a comparison of CO2 emissions showed that ozonation is an ecological alternative to incineration and, most likely, an economical as well, based on the local prices of primary energy sources.

One-step synthesis of nanograss-free TiO2 nanotubes using DTPA-enriched electrolytes

A single-step anodic fabrication of TiO2 nanotubes (TNT) without a surface layer of nanograss was attained in electrolytes containing diethylenetriamine-pentaaceticacid (DTPA) as chelating agent. The role of DTPA concentration and anodization voltage on the final TNT morphology was studied. We discuss chemical aspects of the DTPA effect over the surface of TNTs as well as the physical properties of TNT samples prepared under several anodization conditions. We demonstrate that the DTPA concentration has a significant effect on the final surface morphology of TNTs, leading to a surface free of nanograss. Furthermore, we propose a mechanism that explains this phenomenon.

Development of efficient formulation for the removal of iron sulphide scale in sour production wells

AbstractIron sulphide scale, which exists in different forms, is common in sour oil and gas production wells. Iron sulphide hard scales are difficult to remove with acids, requiring mechanical intervention or the replacement of the production tubing. An environmentally friendly formulation with a high pH is proposed for the removal of both soft and hard iron sulphide scale from oil and gas wells. The formulation consists of DTPA (di‐ethylene tri‐amine penta acetic acid) in addition to K2CO3 as a catalyst. High pressure high temperature solubility experiments were performed under both static and dynamic conditions in the temperature range of 70–150 °C and a constant pressure of 3447.38 kPa. Several combinations of the catalyst and DTPA chelating agent were used to optimize the catalyst/DTPA ratio to achieve maximum scale solubility. Field scale samples were collected and analyzed using XRD. The scale removal efficiency of the proposed formulation outperforms that of the current formulations used in the oil industry, with the added advantage of not releasing H2S. The optimum DTPA concentration is 20 wt% and the optimum catalyst concentration is 9 wt%, which provides a solubility of 90 % of the field scale. In addition, the ecotox profile of the proposed formulation is better than that of the currently used formulations because toxic corrosion inhibitors are not used. The maximum reported corrosion rate for the new formulation is 0.036 kg/m2, which is well below the acceptable limit (< 0.227 kg/m2).

Chemometric study on the electrochemical incineration of diethylenetriaminepentaacetic acid using boron-doped diamond anode

The electrochemical incineration of diethylenetriaminepentaacetic acid (DTPA) with boron-doped diamond (BDD) anode had been initially performed under galvanostatic conditions. The main and interaction effects of four operating parameters (flow rate, applied current density, sulfate concentration and initial DTPA concentration) on mineralization performance were investigated. Under similar experimental conditions, Doehlert matrix (DM) and central composite rotatable design (CCRD) were used as statistical multivariate methods in the optimization of the anodic oxidation processes. A comparison between DM model and CCRD model revealed that the former was more accurate, possibly due to its higher operating level numbers employed (7 levels for two variables). Despite this, these two models resulted in quite similar optimum operating conditions. The maximum TOC removal percentages at 180 min were 76.2% and 73.8% for case of DM and CCRD, respectively. In addition, with the aid of quantum chemistry calculation and LC/MS analysis, a plausible degradation sequence of DTPA on BDD anode was also proposed.

Isolation and identification of bacteria from rotary drum compost of water hyacinth

PurposeThe present work aims to isolate and identify bacterial community from the rotary drum compost of green waste such as the water hyacinth. Compost quality was also investigated with the physicochemical parameters and the heavy metal analysis.MethodsFor rotary drum composting, a waste mixture of 150 kg with water hyacinth, cow dung and sawdust were prepared in the proportion of 6:3:1, respectively. The physicochemical parameters such as pH, temperature, volatile solids and the electrical conductivity were analyzed to detect the compost quality. Pb, Ni, Zn, and Cd were investigated for total heavy metals, toxicity characteristic leaching procedure (TCLP), diethylenetriaminepentaacetic acid (DTPA) and water solubility tests. Consistent and active bacterial community were isolated from the rotary drum compost of water hyacinth. Culture-dependent and culture-independent techniques were approached for the isolation process.ResultsTwelve bacteria were isolated and identified by 16S rDNA sequencing and phylogenetic analysis; they majorly belonged to the Bacillus and Enterobacter family. The analysis of temperature, pH, EC, VS and heavy metals depicted the good quality of compost. Heavy metals concentration was in Pb > Ni > Zn > Cd; however, for Pb, Cd and Ni water solubility remained non-detectable, DTPA concentration for Pb and Cd was also found to be non-detectable.ConclusionsThe microbes in water hyacinth compost are metabolically active degrading the organic matter, surviving in the heavy metal-loaded compost environment. Thus, green waste (water hyacinth) can be utilized to isolate bacterial species in anticipation of their application in heavy metal removal in liquid and solid waste sources for micro-bioremediation.

Thallium Uptake and Translocation in Barley and Sunflower Grown in Hydroponic Conditions

Thallium (Tl) is highly toxic to humans compared with other heavy metals and metalloids, but the risk of its bioaccumulation has not been adequately considered. Thus, Tl uptake and translocation in barley and sunflower under hydroponics with the applications of diethylene triamine pentaacetic acid (DTPA) and citric acid were investigated. Thallium concentrations in roots of both the plants were higher than those in the shoots. Translocation index (TLI) of Tl in barley decreased from 14.9 to 10.0% with increasing Tl treatments in barley, but it increased from 5.9 to 7.5% in sunflower. The concentration of Tl in the barley tissues increased with DTPA applications, but it decreased with citric acid treatments. In contrast, Tl in the sunflower tissues decreased with DTPA treatments, while it increased with the applications of citric acid. However, Tl concentrations in the tissues of both plants were not significantly different between the two concentrations (5.0 and 30 mg/kg) of DTPA and citric acid applications.

Chitosan-Based Reagents Endow Recycled Paper Fibers with Remarkable Physical and Antimicrobial Properties

The aim of the current work was to develop and study a paper additive system that endows recycled paper fibers with strong mechanical and antimicrobial properties. Five different types of modifying agents including succinic acid, carboxymethyladipic acid, butanetetracarboxylic acid, ethylenediaminetetraacetic acid, and diethylenetriaminepentaacetic acid (DTPA) were reacted with soy flour. Approximately 2% modified soy flour additive by mass relative to a old corrugated container (OCC) pulp slurry was mixed before generating a two-dimensional hand sheet for physical testing. DTPA-modified soy-flour-treated OCC pulp displayed better tensile relative to the results from the use of other modifying agents. Soy flour was treated with different DTPA concentrations, times, temperatures, and pH values to determine the optimal modification reaction conditions. Afterward, the DTPA–soy flour was complexed with chitosan to decrease the biodecomposition of soy protein, improve its incorporation into an OCC matrix, and ...

Are analytical standards and reagents really reliable?

Quality assurance is one of the major challenges in analytical chemistry, whatever the scope of application. The quality of analytical standards is very seldom questioned; however, sometimes odd results are obtained, and all the other potential sources of discrepancies are eliminated. So, we investigated the reliability of three analytical standards and reagents implemented for radiochemical and chemical characterizations of nuclear waste. In particular, this work examined the purity of a source of tritiated dodecane, the trueness of a certified concentration value and the purity for a diethylenetriaminepentaacetic acid (DTPA) reagent and the trueness of a certified concentration value for a multi-anion standard used in an interlaboratory comparison exercise. It was shown that the source of tritiated dodecane contains 60 % of tritiated impurities. The trueness of the DTPA concentration certified by the supplier was questioned due to the presence of impurities in the solution. It was proven that the long-term stability of the multi-anion standard was not guaranteed for nitrite. The results clearly demonstrated that, despite the certificates delivered by the suppliers, caution has to be taken toward the reliability of the analytical standards and reagents.

Effects of DTPA application on Growth of Red Pepper (Capsicum annuum L.) and Chemical Properties of Nutrient Accumulated Soil in Plastic film House

This study was conducted to evaluate effects of diethylene triamine penta acetic acid (DTPA) treatment on growth of red pepper and nutrient availability to salt accumulated soil in the plastic film house. The treatments were no application (Control), chemical fertilizers (NPK), DTPA (0.06, 0.13, and 0.19 mM) and the half of chemical fertilizers (NPK) with DTPA 0.06 mM. Fruit yield of red pepper showed no significant difference between the treatments (control, NPK, DTPA 0.06 mM, 0.13 mM, except for DTPA 0.19 mM. Red peppers were killed by DTPA 0.19 mM treatment because the high concentration of DTPA was toxic to crop. However, dry mass (stem and leave) and nutrient uptake of red pepper in DTPA 0.06 mM treatment increased significantly compared with those of control. In particular, nutrient uptake of red pepper in DTPA 0.06 mM treatment increased in the order of Fe, Mn, and Zn > Ca and Mg > K, as the magnitude of the stability constants of DTPA. Thus the application of DTPA 0.06 mM was the most effective for the alleviation of nutrient accumulation in the plastic film house soils.

Application of multi-factorial experimental design to successfully model and optimize inorganic chromium speciation by square wave voltammetry

Response surface methodology (RSM) was used to optimize voltammetric signal of hanging mercury drop electrode (HMDE) for inorganic chromium determination and speciation. Initial solution pH, DTPA (Diethylenetriaminepentaacetic acid) concentration, SWV frequency, pulse height, step potential, accumulation time and accumulation potential were considered as important operating factors through experimental design methodology for Cr(VI) quantification. The central composite and a Box–Behnken designs as response surface design coupled with numerical optimization technique was applied for obtaining the optimum chemical and SWV instrumental conditions as well as the maximum height of chromium reduction peak. Optimum conditions were set as follow: pH6.5, DTPA concentration 5.5mmolL−1, SWV parameters: frequency 500Hz, step potential 0.005V, pulse height 0.1V, accumulation time 120s and accumulation potential −1.10V. Speciation is performed in two separate samples, in the first one Cr(VI) is measured after 40min and DPTA addition. While in the second one, Ce(IV) is added and all Cr(III) is oxidized to Cr(VI) allowing total chromium determination, finally Cr(III) is obtained by difference. Under the optimal experimental conditions, the current reduction peak was proportional to chromium(VI) concentration in the 5–105nmolL−1 range, with detection and quantification limits of 3.77 and 8.47nmolL−1, respectively. Using the proposed method, inorganic chromium speciation was successfully determined in water samples with standard addition method, suggesting that this method can be applied to the quantification of inorganic chromium speciation in water samples.

Chromatographic Separation of Americium(III) from Europium(III) Using Alkyl Diglycolamic Acid

The alkyl derivatives of diglycolamic acid (DGAA) (alkyl = butyl to decyl) were synthesized and characterized by 1H and 13C nmr, and IR spectroscopy. The diglycolamic acids were impregnated in Tulsion ADS 400 for the chromatographic separation of hazardous Am(III) and Eu(III). The extraction behavior of Am(III) and Eu(III) in the impregnated resin was studied as a function of various parameters such as aqueous phase pH, concentration of DGAA, and diethylenetriaminepentaacetic acid (DTPA), etc. The distribution coefficient (Kd) of Am(III) and Eu(III) in the resin phase increased with increase in pH of aqueous phase and loading of DGAA in the resin. The concentration of DTPA needed for efficient separation of Am(III) from Eu(III) was optimized and the performance of the resin under dynamic extraction conditions was assessed by following the breakthrough curve in the column study using octyl derivative of DGAA. The conditions needed for the elution of Am(III) alone from the column was performed using 0.001 M DTPA solution at pH 2.5. The study confirmed the feasibility of separating Am(III) from Eu(III) using octyl-DGAA by extraction chromatography.

Zinc and zinc chelators modify taurine transport in rat retinal cells.

Zinc regulates Na(+)/Cl(-)-dependent transporters, similar to taurine one, such as those for dopamine, serotonin and norepinephrine. This study examined the ex vivo effect of zinc (ZnSO4), N,N,N,N-tetraquis-(2-piridilmetil)etilendiamino (TPEN) and diethylenetriaminepenta-acetic acid (DTPA), intracellular and extracellular zinc chelators, respectively, on rat retina [(3)H]taurine transport. Isolated cells were incubated in Locke solution with 100 nM of [(3)H]taurine for 25 s. Different concentrations of ZnSO4 (0.5-200 μM) were used. Low concentrations of ZnSO4 (30 and 40 μM) increased the transport, while higher concentrations (100, 150 and 200 μM) decreased it. Various concentrations of TPEN (1-200 μM) were added. Intermediate concentrations of TPEN (10-60 μM) significantly decreased [(3)H]taurine transport. The presence of TPEN, 20 μM, plus ZnSO4 reversed the effect of TPEN alone. Several concentrations of DTPA (1-500 μM) were also investigated. Reduction of transport took place at high concentrations of the chelator (100, 250 and 500 μM). DTPA, 500 μM, plus ZnSO4, did not modify the effect of it. These results indicate that zinc modulates taurine transport in a concentration-dependent manner, directly acting on the transporter or by forming taurine-zinc complexes in cell membranes.