Determination Of Uranium In Seawater Research Articles

Comparison of Analytical Methods for the Determination of Uranium in Seawater Using Inductively Coupled Plasma Mass Spectrometry

Trace element determinations in seawater by inductively coupled plasma mass spectrometry are analytically challenging due to the typically very low concentrations of the trace elements and the potential interference of the salt matrix. In this study, we did a comparison for uranium analysis using inductively coupled plasma mass spectrometry (ICP-MS) of Sequim Bay seawater samples and three seawater certified reference materials (SLEW-3, CASS-5, and NASS-6) using eight different analytical approaches. The methods evaluated include the following: direct analysis, Fe/Pd reductive precipitation, off-line preconcentration using the actinide specific resin, UTEVA, standard addition calibration, on-line automated dilution using an external calibration with and without matrix matching, and on-line automated preconcentration using the seaFast preconcentration resin. The two methods which produced the most accurate results were the method of standard addition calibration and off-line preconcentration using the UTEV...

Determination of uranium in seawater, biological samples and sediments using laser induced fluorescence spectrometry

Uranium has been determined in seawater, biological samples and sediments using laser induced fluorescence spectrometry (LIFS). The biological samples and sediments are digested with a mixture of HNO3, HClO4 and HF. The conductivity of the seawater should be below 5.0 mS and the pH of the sample should be in the range 6.5–9.0. The volume of the reagent used to enhance the fluorescence intensity was 0.5 ml. Comparison with other methods was favorable, LIFS being rapid, simple and sensitive, and well suited to environmental monitoring.

Standardization of solvent extraction procedure for determination of uranium in seawater

Solvent extraction procedure using ammonium pyrolidine dithiocarbamate complexing agent in methyl isobutyl ketone organic phase and acid exchange back-extraction is described for the simultaneous quantitative pre-concentration of uranium in seawater followed by its determination by differential pulse adsorptive stripping voltammetry. Solvent extraction time is optimized for extraction of uranium from seawater. Solvent extraction efficiency for uranium in seawater at different pH was carried out. The method gives a recovery of 98 ± 2 % for 400 mL sample at pH 3.0 ± 0.02, facilitating the rapid and interference free analysis of seawater samples.

A RP-HPLC Method Using -Hydroxy Isobutyric Acid for Preconcentration and Determination of Uranium in Seawater

A high-performance liquid chromatographic (HPLC) method is developed for the determination of uranium (U), present at ppb levels, in seawater. α-Hydroxy isobutyric acid is used as the complexing agent for preconcentration as well as separation of U from other interfering metal ions (Mo, V, Ti, Ni etc.). A C 18 reversed-phase monolithic column and α-HIBA of pH 6-7 are employed for the selective preconcentration of U. Mobile phase consisting of α-HIBA of pH 2 and MeOH is used for elution of adsorbed U which is monitored after post-column derivatisation with Arsenazo(III), using a spectrophotometric detector. The methodology is validated by using simulated as well as seawater samples. Quantitative recovery for U is possible with linear response over a concentration range of 1 to 30 ppb of U. Metal ions which have been previously reported to give interferences do not give any problem in the present approach. The developed HPLC methodology is validated by comparing the results with those of isotope dilution-thermal ionization mass spectrometry.

Determination of uranium in seawater by flow-injection preconcentration on dodecylamidoxime-impregnated resin and spectrophotometric detection

A flow injection method has been developed for the determination of uranium in seawater combining the on-line preconcentration with spectrophotometric detection. An aliquot (10mL) of the seawater sample adjusted to pH 5.5 was injected into the analytical system and uranium was adsorbed on the column packed with styrene-divinylbenzene copolymer resin (Bio-Beads SM-2) modified with dodecylamidoxime which showed high selectivity to uranium. Uranium was then eluted with 0.01M hydrochloric acid and detected spectrophotometrically after the reaction with Chlorophosphonazo III. Interference from calcium and strontium was masked with cyclohexanediaminetetraacetic acid added to the chromogenic reagent solution. The sample throughput, the detection limit (3σ), and the preconcentration factor were 23 per hour, 0.13μg/L, and 20, respectively, when the sample injection volume was kept at 10mL. The precision at the 2μg/L level was less than 4% (RSD). The proposed method was applied to the determination of uranium in the seawater samples collected off the Boso peninsula, Japan and the uranium concentration was found to be ca. 3μg/L, which is close to the literature data. The yield of the recovery test ranged from 95% to 99%.

Direct determination of uranium in seawater by laser fluorimetry

A method for estimation of uranium in seawater by using steady state laser flourimetry is described. Uranium present in seawater, in concentration of approximately 3 ng ml −1 was estimated without prior separation of matrix. Quenching effect of major ions (Cl −, Na +, SO 4 −, Mg +, Ca +, K +, HCO 3 −, Br −) present in seawater on fluorescence intensity of uranium was studied. The concentration of phosphoric acid required for maximum enhancement of fluorescence intensity was optimized and was found to be 5%. Similarly the volume of concentrated nitric acid required to eliminate the quenching effect of chloride and bromide completely from 5 ml of seawater were optimized and was found to be 3 ml. A simple equation was derived using steady state fluorescence correction method and was used for calculation of uranium concentration in seawater samples. The method has a precesion of 1% (1 s, n = 3). The values obtained from laser fluorimetry were validated by analyzing the same samples by linear sweep adsorptive stripping voltametry (LSASV) of the uranium–chloranilic acid (2,5-dichloro-3,6-dihydroxy-1,4-benzoquinone) complex. Both the values are well in agreement.

Uranium determination in seawater by total reflection X-ray fluorescence spectrometry

A study regarding uranium determination in seawater by total reflection X-ray fluorescence (TXRF) spectrometry is reported. Uranium, present in seawater in concentration of about 3.3 ng/mL, was selectively extracted in diethyl ether and determined by TXRF after its preconcentration by evaporation and subsequent dissolution in a small volume of 1.5% suprapure HNO 3. Yttrium was used as an internal standard. Before using diethyl ether for selective extraction of uranium from seawater, its extraction behavior for different elements was studied using a multielement standard solution having elemental concentrations in 5 ng/mL levels. It was observed that the extraction efficiency of diethyl ether for uranium was about 100% whereas for other elements it was negligible. The detection limit of TXRF method for uranium in seawater samples after pre-concentration step approaches to 67 pg/mL. The concentrations of uranium in seawater samples determined by TXRF are in good agreement with the values reported in the literature. The method shows a precision within 5% (1 σ). The study reveals that TXRF can be used as a fast analytical technique for the determination of uranium in seawater.

Speciation and spectrophotometric determination of uranium in seawater

A series of ion-exchange and extraction procedures for the separation of uranium from seawater samples and subsequent spectrophotometric determination of uranium in seawater by means of arsenazo(III) is described. According to the measurements performed by means of traced samples at every stage of separation, the yield of the pre-analytical procedures is generally over 90% and the separation of uranium very selective. The mean uranium concentration in seawater samples collected from five different coastal areas in Cyprus was found to be 3.2 ± 0.2 & micro; g L-1. Uranium in seawater is stable in its hexavalent oxidation state and UO2 (CO3)34- is the predominant species under normal coastal conditions (pH ≥ 8, EH ≥ 0.35 mV, 1 atm and 0.03% CO2).

A simple co-precipitation inductively coupled plasma mass spectrometric method for the determination of uranium in seawater.

Inductively coupled plasma mass spectrometry (ICP-MS) was used in the determination of 238uranium in seawater after concentration by a simplified co-precipitation with iron hydroxide. Ocean water and reference seawater were used in the study. The co-precipitation method required a smaller sample volume (10 fold less), and less column separation to recover the uranium from the seawater matrix, compared to the original iron hydroxide method. The direct seawater dilution technique requires only a small seawater volume (0.5 mL) and offers a rapid, reliable method for uranium analysis in seawater compared to traditional methods. Comparison of the results for simple co-precipitation, direct dilution of seawater, and theoretical uranium values based on salinity concentrations, yielded negligible differences. Data from this work show that the certified value for NASS-4 is low.

Spectrophotometric determination of uranium in natural water with the new chromogenic reagent p-carboxychlorophosphonazo

The synthesis and purification of p-carboxychlorophosphonazo (CPApK) are described. In acidic medium, uranium forms a sensitive β-type complex with CPApK ( ε = 1.78 × 10 5 l mol −1 cm −1 at 714 nm). In the presence of polyvinyl alcohol (PVA), the molar absorptivity increases further ( ε = 2.72 × 10 5 l mol −1 cm −1). Beer's law is obeyed for 4–12 μg of uranium in 25 ml of solution. A method has been satisfactorily developed for the Spectrophotometric determination of uranium in seawater and lake water with a prior adsorption and desorption.

Direct Determination of Uranium in Seawater by Absorption Spectrophotometry

Direct Determination of Uranium in Seawater by Absorption Spectrophotometry

DETERMINATION OF URANIUM (VI) IN SEAWATER BY SOLID-STATE SPECTROPHOTOMETRY

A solid-state spectrophotometric method has been developed for the determination of uranium in seawater. The method is based on the enrichment of uranium as the 3-[4-(5-bromo-2-pyridylazo)-3-hydroxy-N-propylanilino] propanesulphonate (5-Br-PAPS) complex on a membrane filter and the direct determination of the reflection absorbance of the complex by densitometry. The ion-pair precipitate formed between Zephiramine and perchlorate ions is effective for the enrichment of the uranium(VI) -5-Br-PAPS complex on the membrane filter. The selectivity of the method is improved with the use of trans-cyclohexane-1, 2-diaminetetraacetic acid (CyDTA) and ethylenediamine. The concentration of uranium(VI) in a seawater sample was found to be 3.26μg/l with a relative standard deviation of 2.2% (n=21)

Anion-exchange enrichment and spectrophotometric determination of uranium in sea-water

A method is proposed for the determination of uranium in sea-water. The uranium is strongly sorbed on a strongly basic anion-exchange resin (Cl − form) from acidified sea-water containing sodium azide (0.3 M) and is easily eluted with 1 M hydrochloric acid. Uranium in the effluent can be determined spectrophotometrically with Arsenazo III. The combined method allows easy and selective determination of uranium in sea-water without using a sophisticated adsorbent. The overall recovery and precision are satisfactory at the 3 μg/1. level.

Spectrophotometric determination of uranium in sea water with thiocyanate and rhodamine B

Spectrophotometric Determination of Uranium in Sea-Water with Thiocyanate and Rhodamine B In the presence of a large excess of thiocyanate uranium(VI) forms a violet colour with Rhodamine B. The complex can be stabilized by addition of poly (vinyl alcohol). The calibration graph for measurement at 600 nm is linear in the range 0.5–10μg of uranium per 25ml, the molar absorptivity being 3.56×1051-mole−1·cm−1. The effect of foreign ions has been studied and the method can be applied to the determination of uranium in sea-water, with reliable results. Uranium is preconcentrated from sea-water by a flotation procedure with toluene in presence of benzoate and Safranine T, with nitrilotriacetic acid as masking agent. The method is highly selective for uranium, with a recovery of 97.9–99.2%.

Preconcentration of Uranium in Seawater with Heterocyclic Azo Dyes Supported on Silica Gel

Abstract The chelating adsorbents, heterocyclic azo dyes supported on silica gel, were prepared and their adsorption behaviors of metal ions were investigated. The 1-(2-pyridylazo)-2-naphthol(PAN)-SG and 2-(2-thiazolylazo)-p-cresol(TAC)-SG show greater affinity for UO2(II) and ZrO(II), compared with the other metal ions like Cu, Cd, Fe and alkaline earths. Trace uranyl can be quantitatively retained on the column of the gels at neutral pH region and flow-rate 3–4 ml/min. The uranyl retained is easily eluted from the column bed with a mixture of acetone and nitric acid(9:1 v/v) and determined by spectrophotometry using Arsenazo-III. Matrix components in seawater do not interfere and the spiked recovery of uranyl in artificial seawater was found to be average 98.6 %, with the relative standard deviation of 1.08 %. Both gels were applied to the determination of uranium in seawater with satisfactory results.

Liquid Chromatographic Determination of Uranium in Seawater with Coulometric Detection

Liquid Chromatographic Determination of Uranium in Seawater with Coulometric Detection

An improved separation and determination of uranium in seawater

An improved separation and determination of uranium in seawater

Co-crystallization of ultramicro quantities of various elements with α-nitroso-β-naphthol determination of uranium in seawater

The co-crystallization of ultramicro quantities of various elements with α-nitroso-β-naphthol was investigated. Radiotracer techniques were employed to measure the quantitative removal of these elements from aqueous solutions. Conditions were developed for the separation of cerium(III), zinc, iron(III), cobalt(II), zirconium and uranium(VI) by this process. Plutonium(IV) and ruthenium(III) co-crystallized less completely while sodium, strontium and antimony(III) remained largely associated with the mother liquor. The process was applied in the determination of uranium in seawater. The measured amount was 3.1 ± 0.1 μg uranium/l.

Co-crystallization of ultramicro quantities of various elements with α-nitroso-β-naphthol determination of uranium in seawater

The co-crystallization of ultramicro quantities of various elements with α-nitrosu-β-naphthol was investigated. Radiotracer techniques were employed to measure the quantitative removal of these elements from aqueous solutions. Conditions were developed for the separation of cerium(III), zinc, iron(III), cobalt(II), zirconium and uranium(VI) by this process, Plutonium (IV) and ruthenium(III) co-crystallized less completely while sodium, strontium and antimony(III) remained largely associated with the mother liquor. The process was applied in the determination of uranium in seawater. The measured amount was 3.1 ± 0.1 μg uranium/1.