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1.
This paper reports silica gel loaded with p-tert-butylcalix[8]arene as a new solid phase extractor for determination of trace level of uranium. Effective extraction conditions
were optimized in column methods prior to determination by spectrophotometry using arsenazo(III). The results showed that
U(VI) ions can be sorbed at pH 6 in a mini-column and quantitative recovery of U(VI) (>95–98%) was achieved by stripping 0.4 mol L−1 HCl. The sorption capacity of the functionalized sorbent is 0.072 mmol uranium(VI) g−1 modified silica gel. The relative standard deviation and detection limit were 1.2% (n = 10) for 1 μg uranium(VI) mL−1 solution and 0.038 μg L−1, respectively. The method was employed to the preconcentration of U(VI) ions from spiked ground water samples. 相似文献
2.
Elif Ant Bursali Melek Merdivan Muruvvet Yurdakoc 《Journal of Radioanalytical and Nuclear Chemistry》2010,283(2):471-476
Olive cake as low-cost abundantly available sorbent has been characterized by N2 at 77 K adsorption, porosity analysis, elemental analysis and IR spectra and has been used for preconcentrating of uranium(VI)
and thorium(IV) ions prior to their determination spectrophotometrically. The optimum pH values for quantitative sorption
of U(VI) and Th(IV) are 4–7 and 3–7, respectively. The enrichment factor for the preconcentration of U(VI) and Th(IV) were
found to be 125 and 75 in the given order. The sorption capacity of olive cake is in the range of 2,260–15,000 μg g−1 for Th(IV) and in the range of 1,090–17,000 μg g−1 for U(VI) at pH 3–7. The sorbent exhibits good reusability and the uptake and stripping of the studied ions were fairly rapid.
The elution of U(VI) and Th(IV) was performed with 0.3–1 M HCl/1–2 M HNO3 and 0.3–0.8 M HCl/1 M HNO3, respectively. The precision of the method was 1.8 RSD% for U(VI) and 2.5 RSD% for Th(IV) in a concentration of 1.00 μg mL−1 for 10 replicate analysis. The influence of some electrolytes and cations as interferents was discussed. Separation of U(VI)
and Th(IV) from other metal ions in synthetic solution was achieved. 相似文献
3.
5,10,15,20-tetrakis(phenoxy acetic acid) porphyrin (PAAP) was covalently linked to Merrifield chloromethylated resin. Characterization
of PAAP and the modified polymeric matrix were performed by 1H NMR, FTIR and elemental analysis. The sorbent was used for the separation and enrichment of the d-electron metals (Mn(II), Co(II), Ni(II), Cu(II) and Zn(II)) at pH 6–8 and of the f-electron metals U(VI) and Th(IV) at pH 4–5. The metals ions were preconcentrated with a concentration factor range of 115–215
and then determined by flame atomic absorption spectrometry or visible spectrophotometry using Arsenazo(III). The retained
metals were eluted with 2.0 mol L−1 HNO3 in the case of the d-electron metals and 0.1/0.25 mol L−1 HCl in the case of the f-electron metals. The procedure was validated by analyzing the NIST standard reference material 2709 (San Joaquin Soil).
Correspondence: Melek Merdivan, Chemistry Department, Faculty of Arts and Sciences, Dokuz Eylul University, 35160 Buca, Izmir,
Turkey 相似文献
4.
Weihua Zou Lei Zhao Runping Han 《Journal of Radioanalytical and Nuclear Chemistry》2011,288(1):239-249
In this paper, the sorption properties of manganese oxide coated sand (MOCS) towards uranium(VI) from aqueous solutions were
studied in a batch adsorption system. Scanning electron microscope (SEM) and infrared (IR) analyses were used to characterize
MOCS. Parameters affecting the adsorption of uranium(VI), such as the contact time, salt concentration, competitive ions,
temperature and initial uranium(VI) concentration, were investigated. The equilibrium adsorption data were analyzed by Langmuir,
Freundlich and Redlich–Peterson models using nonlinear regressive analysis. The results indicated that the Langmuir and Redlich–Peterson
models provided the best correlation of experimental data. The kinetic experimental data were analyzed using three kinetic
equations including pseudo-first order equation, pseudo-second order equation and intraparticle diffusion model to examine
the mechanism of adsorption and potential rate-controlling step. The process mechanism was found to be complex, consisting
of both surface adsorption and pore diffusion. The effective diffusion parameter D
i values estimated in the order of 10−7 cm2 s−1 indicated that the intraparticle diffusion was not the rate-controlling step. Thermodynamic study showed that the adsorption
was a spontaneous, endothermic process. Adsorbed U(VI) ions were desorbed effectively (about 94.7%) by 0.1 mol L−1 HNO3. The results indicated that MOCS can be used as an effective adsorbent for the treatment of industrial wastewaters contaminated
with U(VI) ions. 相似文献
5.
Extraction behavior of 1 × 10−2–0.1 M U(VI) from aqueous phases containing 0.86 M Th(IV) at 4 M HNO3 in 1.1 M tributyl phosphate (TBP) and 1.1 M N,N-dihexyl octanamide (DHOA) solutions in different diluents viz. n-dodecane, 10% 1-octanol + n-dodecane, and decahydronaphthalene (decalin) was studied. Third-phase formation was observed in both the extractants using
n-dodecane as diluent. There was a gradual decrease in Th(IV) concentration in the third-phase (heavy organic phase, HOP) with
increased aqueous U(VI) concentration [0.71 M (no U(VI))–0.61 M (0.1 M U(VI)) for TBP; 0.27 M (no U(VI))–0.22 M (0.1 M U(VI))
for DHOA]. The HOP volume in case of DHOA was ~2.2 times of that of TBP. Uranium concentration in HOP increased with its initial
concentration in the aqueous phase [from 1.8 × 10−2 M (0.01 M U(VI))–0.162 M (0.1 M U(VI)) for TBP; from 1.4 × 10−2 M (0.01 M U(VI))–0.14 M (0.1 M U(VI)) for DHOA] suggesting that Th(IV) was being replaced by U(VI). An empirical correlation
was developed for predicting the concentrations of uranium and thorium in HOP for both the extractants. No third-phase appeared
during the extraction of uranium and thorium from the aqueous phases employing 10% 1-octanol + n-dodecane, or decalin as diluents, and therefore, were better choices as diluent for alleviating the third-phase formation
during the reprocessing of spent thorium based fuels, and for the recovery of thorium from high-level waste solutions. 相似文献
6.
Modified Sorrel’s cement was prepared by the addition of ferric chloride. The modified cement (MF5) was analyzed and characterized
by different methods. Adsorption of Gd(III) and U(VI) ions in carbonate solution has been studied separately as a function
of pH, contact time, adsorbent weight, carbonate concentration, concentration of Gd(III) and U(VI) and temperature. From equilibrium
data obtained, the values of Δ H, Δ S and Δ G were found to equal −30.9 kJ ⋅ mol−1, −85.4 J ⋅ mol−1 ⋅,K−1, and −5.4 KJ ⋅ mol−1, respectively, for Gd(III) and 18.9 kJ ⋅ mol−1, 67.8 J ⋅ mol−1 K−1 and −1.3 KJ ⋅ mol−1, respectively, for U(VI). The equilibrium data obtained have been found to fit both Langmuir and Freundlich adsorption isotherms.
The batch kinetic of Gd(III) and U(VI) on modified Sorrel’s cement (MF5) with the thermodynamic parameters from carbonate
solution were studied to explain the mechanistic aspects of the adsorption process. Several kinetic models were used to test
the experimental rate data and to examine the controlling mechanism of the adsorption process. Various parameters such as
effective diffusion coefficient and activation energy of activation were evaluated. The adsorption of Gd(III) and U(VI) on
the MF5 adsorbent follows first-order reversible kinetics. The forward and backward constants for adsorption, k
1and k
2 have been calculated at different temperatures between 10 and 60∘C. Form kinetic study, the values of Δ H
* and Δ S
* were calculated for Gd(III) and U(VI) at 25∘C. It is found that Δ H
* equals −14.8 kJmol−1 and 7.2 kJmol−1 for Gd(III) and U(VI), respectively, while Δ S
* were found equal −95.7 Jmol−1K−1 and −70.5 Jmol−1K−1 for Gd(III) and U(VI), respectively. The study showed that the pore diffusion is the rate limiting for Gd(III) and (VI). 相似文献
7.
Sujoy Biswas K. N. Hareendran D. K. Singh J. N. Sharma S. B. Roy 《Journal of Radioanalytical and Nuclear Chemistry》2010,283(3):665-668
Extraction behavior of U(VI) and Th(IV) from nitric acid medium is investigated using organo-phosphorous extractant, tri(butoxyethyl)
phosphate in n-paraffin at room temperature (27 ± 1 °C). The effect of diluents, nitric acid concentration as well as extractant concentration
on extraction of U(VI) and Th(IV) are evaluated. Extraction of U(VI) and Th(IV) from nitric acid medium proceeds via solvation
mechanism. Slope analysis technique showed the formation of neutral complexes of the type of UO2(NO3)2·2TBEP and Th(NO3)4·3TBEP with U(VI) and Th(IV) respectively in the organic phase. The FTIR data showed shifting of P=O stretching frequency
from 1,282 to 1,217 cm−1 indicating the strong complexation of P=O group with UO2
2+ ions in the organic phase. Effect of stripping agents, other metal ions and their separation with respect to U(VI) extraction
has also been investigated. 相似文献
8.
D. Leyva J. Estévez A. Montero I. Pupo 《Journal of Radioanalytical and Nuclear Chemistry》2012,291(3):699-705
A sensitive and non chromatographic analytical procedure for the separation of inorganic selenium species in natural water
has been performed. A combination of APDC coprecipitation and determination by an absolute thin layer Energy dispersive X-ray
fluorescence spectrometry method was used. The influence of various analytical parameters such as element concentration, oxidation
states and pH on the recoveries of Se (IV) was examined. The presence of organic matter and bicarbonate anions, typical components
in Cuban groundwater samples, was also tested. Negligible matrix effects were observed. At pH 4 a 100% recovery was found
for Se (IV). The coprecipitation recovery of the oxidized selenium species (Se (VI)) was null for the selected concentration
range (5–100 μg L−1). When the Se (VI) was reduced by heating the solution with 4 mol L−1 HCl, quantitative recovery was also obtained. The determination of total selenium was conducted by the application of the
oxidation–reduction process and the analytical procedure for Se (IV). Se (VI) content was calculated as the difference between
total selenium and Se (IV). The detection limit was 0.13 μg L−1. The relative standard deviation was lower than 3.5% for 5 μg L−1 of Se (IV). The trueness of the method was verified by using standardized hydride generation-atomic absorption spectrometry
technique. The results obtained using the EDXRF technique were in good agreement with the ones determined by HG-AAS. The proposed
method was applied to the determination of Se (IV) in surface water and groundwater samples. 相似文献
9.
Yalan Liu Liyong Yuan Yali Yuan Jianhui Lan Zijie Li Yixiao Feng Yuliang Zhao Zhifang Chai Weiqun Shi 《Journal of Radioanalytical and Nuclear Chemistry》2012,292(2):803-810
Uranium is one of the most hazardous heavy metal due to its long half-life radioactivity, high toxicity and mobility as aqueous
uranyl ion (UO2
2+) under ordinary environmental conditions. Herein, amino functionalized SBA-15 (APSS) was developed as a rapid and efficient
sorbent for removal of U(VI) from the environment. The APSS sample was synthesized by grafting method and was characterized
by SEM, NMR, SAXS, and N2 sorption/desorption isothermal experiments. The sorption of U(VI) by APSS was investigated under different conditions of
pH, contact time, initial U(VI) concentration, ionic strength and solid–liquid ratio. The results show that the sorption of
U(VI) by APSS is strongly dependent on pH but independent of ionic strength and solid–liquid ratios (m/V). The sorption is ultrafast with an equilibrium time of less than 30 min, and the sorption capacity is as large as 409 mg/g
at pH 5.3 ± 0.1. Besides, the U(VI) sorption by APSS from extremely diluted solution and the desorption of U(VI) from APSS
were also studied. It is found that 100 mg of APSS can almost completely remove the U(VI) ions from 4 L aqueous solution with
the U(VI) concentration as low as 4.2 ppb and the sorbed U(VI) can be completely desorbed by 0.1 mol/L nitric acid. The results
strongly reveal the high performance of the APSS material in the removal and preconcentration of U(VI) from the aqueous solution. 相似文献
10.
Grabarczyk M 《Analytical and bioanalytical chemistry》2008,390(3):979-986
A simple and fast catalytic adsorptive stripping voltammetric procedure for trace determination of Cr(VI) in natural samples
containing high concentrations of humic substances has been developed. The procedure for chromium determination in the presence
of DTPA and nitrates was employed as the initial method. In order to enhance the selectivity vs. Cr(III) the measurements
were performed at 40°C. Interference from dissolved organic matter such as humic and fulvic acids was drastically decreased
by adding Amberlite XAD-7 resin to the voltammetric cell before the deaeration step. The whole procedure was applied to a
single cell, which allowed monitoring of the voltammetric scan. Optimum conditions for removing humic and fulvic acids due
to their adsorption on XAD-7 resin were evaluated. The use of XAD-7 resin also minimize interferences from various cationic,
anionic, and nonionic surfactants. The calibration graph for Cr(VI) for an accumulation time of 30 s was linear in the range
5 × 10−10 to 5 × 10−8 mol L−1. The relative standard deviation for determination of Cr(VI) at a concentration of 1 × 10−8 mol L−1 was 3.5% (n = 5). The detection limit estimated from 3 times the standard deviation for low Cr(VI) concentrations and an accumulation
time of 30 s was about 1.3 × 10−10 mol L−1. The proposed method was successfully applied to Cr(VI) determination at trace levels in soil samples. 相似文献
11.
Determination of tetracycline residues in soil by pressurized liquid extraction and liquid chromatography tandem mass spectrometry 总被引:2,自引:0,他引:2
Vicente Andreu Pablo Vazquez-Roig Cristina Blasco Yolanda Picó 《Analytical and bioanalytical chemistry》2009,394(5):1329-1339
An optimized extraction and cleanup method for the analysis of chlortetracycline (CTC), doxycycline (DC), oxytetracycline
(OTC) and tetracycline (TC) in soil is presented. Soil extraction in a pressurized liquid extraction system, followed by extract
clean up using solid-phase extraction (SPE) and tetracycline determination by liquid chromatography tandem mass spectrometry
(LC-MS/MS) provided appropriate efficiency and reproducibility. Different dispersing agents and solvents for soil extraction
and several SPE cartridges for cleanup were compared. The best extraction results were obtained using ethylenediamine tetraacetic
acid-treated sand as dispersing agent, and water at 70 °C. The most effective cleanup was obtained using Strata-XTM sorbent in combination with a strong anion exchange cartridge. Recoveries ranged from 71% to 96% and precision, as indicated
by the relative standard deviations, was within the range of 8–15%. The limits of quantification (LOQs) by using LC-MS/MS,
based on signal-to-noise ratio (S/N) of 10, ranged from 1 μg kg−1 for TC to 5 μg kg−1 for CTC. These results pointed out that this technique is appropriate to determine tetracyclines in soils. Analysis of 100
samples taken in the Valencian Community revealed that, in soil, up to 5 μg kg−1 CTC, 15 μg kg−1 OTC, 18 μg kg−1 TC, and 12 μg kg−1 DC could be detected. Detection of the analytes in several samples, which typify great part of the Spanish agricultural soils,
should be outlined as most important result of this study.
Electronic supplementary material The online version of this article (doi: ) contains supplementary material, which is available to authorized users. 相似文献
12.
M N Matos Reyes M L Cervera M de la Guardia 《Analytical and bioanalytical chemistry》2009,394(6):1557-1562
A sensitive and simple analytical method has been developed for determination of Sb(III), Sb(V), Se(IV), Se(VI), Te(IV), Te(VI),
and Bi(III) in garlic samples by using hydride-generation–atomic-fluorescence spectrometry (HG–AFS). The method is based on
a single extraction of the inorganic species by sonication at room temperature with 1 mol L−1 H2SO4 and washing of the solid phase with 0.1% (w/v) EDTA, followed by measurement of the corresponding hydrides generated under two different experimental conditions directly
and after a pre-reduction step. The limit of detection of the method was 0.7 ng g−1 for Sb(III), 1.0 ng g−1 for Sb(V), 1.3 ng g−1 for Se(IV), 1.0 ng g−1 for Se(VI), 1.1 ng g−1 for Te(IV), 0.5 ng g−1 for Te(VI), and 0.9 ng g−1 for Bi(III), in all cases expressed in terms of sample dry weight. 相似文献
13.
V. R. Bhandiwad Rajendra Swarup S. K. Patil 《Journal of Radioanalytical and Nuclear Chemistry》1979,52(1):5-14
The extraction of Np(IV), Pu(IV) and U(VI) from aqueous hydrochloric acid into quaternary amines has been studied. The dependence
of the distribution coefficient on amine concentration suggests that the actinide ions extracted are NpCl
6
2−
PuCl
6
2−
and UO2Cl
4
2−
. This is further supported by the absorption spectra of the amine extracts of these actinide ions. Based on the extraction
data obtained, a simple method for the separation of typical metal ions such as Cs, lanthanides and Zr from U(VI) and Pu(IV)
is suggested. 相似文献
14.
Silica gel surface was chemically functionalized by reaction the silanol from the silica surface with 3-chloropropyltrimethoxysilane followed by reaction with Sulfasalazine. This new sorbent has been used for the preconcentration of low levels of U(VI) ions from an aqueous phase. Parameters involved in extraction efficiency such as pH, weight of the sorbent, volume of sample and eluent were optimized in batch and column methods prior to determination by spectrophotometry using arsenazo(III) reagent. The results showed that U(VI) ions can be sorbed at pH range of 5.0–6.0 in a minicolumn and quantitative recovery of U(VI) (>98.0?±?1.6%) was achieved by stripping with 2.5 mL of 0.1 mol L?1 HCl. The sorption capacity of the functionalized silica gel was 1.15 mmol g?1 of U(VI). A linear calibration graph was obtained over the concentration range of 0.02–27.0 μg mL?1 with a limit of detection of 1 μg L?1 in treatment with 1000 mL of the U(VI) solution in which the preconcentration factor was as high as 400. The method was employed to the preconcentration of U(VI) ions from spiked ground water and synthetic sea water samples. 相似文献
15.
Hongxia Zhang Qiang Tang Zuyi Tao 《Journal of Radioanalytical and Nuclear Chemistry》2009,279(3):855-861
Six column experiments were performed and seven breakthrough curves (BTCs) and seven displacement (desorption) curves (DPCs)
of phosphate and U(VI) were obtained, which demonstrated the effects of phosphate and Cr3+ on the sorption and transport of U(VI) on a silica column at pH 3 and uranium concentration 10−5–10−6 mol/L of the influent. It was found that in the presence of phosphate sorbed preliminarily on the silica column, the amount
of U(VI) sorbed on this column is significantly increased owing to the interaction of U(VI) with phosphate sorbed as compared
with that in the absence of phosphate, and the breakthrough and the mean residence time of U(VI) on this column are similar
to those in the absence of phosphate. While the effect of simultaneous injection of Cr3+ on the retardation of U(VI) on the silica column, the maximum concentration of BTC and the amount of U(VI) sorbed was found
to be insignificant. Transport and sorption studies of U(VI) are important, since all uranium isotopes are radioactive, there
is a need to understand the potential for migration away from radioactive waste storage and mill tailing sites. 相似文献
16.
Abdelhakim Kadous Mohamed Amine Didi Didier Villemin 《Journal of Radioanalytical and Nuclear Chemistry》2011,288(2):553-561
Removal of uranium(VI) ions from acetate medium in aqueous solution was investigated using Lewatit TP260 (weakly acidic, macroporous-type
ion exchange resin with chelating aminomethylphosphonic functional groups) in batch system. The parameters that affect the
uranium(VI) sorption, such as contact time, solution pH, initial uranium(VI) concentration, adsorbent dose and temperature
have been investigated. Results have been analyzed by Langmuir and Freundlich isotherm; the former was more suitable to describe
the sorption process. The moving boundary particle diffusion model only fits the initial metal adsorption on the resin. The
rate constant for the uranium sorption by Lewatit TP260 was 0.441 min−1 from the first order rate equation. The total sorption capacity was found to be 58.33 mg g−1 under optimum experimental conditions. Thermodynamic parameters (ΔH = 61.74 kJ/mol; ΔS = 215.3 J/mol K; ΔG = −2.856 kJ/mol) showed the adsorption of an endothermic process and spontaneous nature, respectively. 相似文献
17.
Muhammad Haleem Khan Syed Manzoor Hussain Bukhari Akbar Ali Khurram Liaqat Srosh Fazal 《Journal of Radioanalytical and Nuclear Chemistry》2011,289(1):113-119
A simple, sensitive and efficient spectrophotometric method is proposed for rapid determination of uranium using arsenazo-III
in perchloric acid. The reaction between arsenazo-III and U(VI) was instantaneous in 3 mol L−1 HClO4.
N-cetyl-N,N,N-trimethylammonium bromide was used for increasing the sensitivity and selectivity of the complex. The absorbance remains
stable for over 48 h in the presence of surfactant. The method allows the determination of uranium in the range of 1–20 μg g−1 with a molar absorptivity of 3.9 × 105 dm3 mol−1 cm−1 at 681 nm. Sandell’s sensitivity of the complex was calculated to be 6.4 ng cm−2 at λmax 681 nm. A significant enhancement was achieved in the sensitivity of the proposed method whereas, Relative Standard Deviation
was reduced from 4.5 to 1.7% in the presence of surfactant. Among various diverse ions studied, fluoride, cyanide, citrate,
sulfate and phosphate interfere beyond the tolerance limit. Among cations only Cr3+ and Co2+ decreased the normal absorbance. The validity of the reported method was tested by determining uranium in the environmental
water samples and Standard Reference Material. The results agreed closely with the reported values. The proposed method is
new, easy in operation and better in sensitivity than many of the existing methods. 相似文献
18.
A new chelating polymeric sorbent is developed using Merrifield chloromethylated resin anchored with calix[4]arene-o-vanillinsemicarbazone for simultaneous separation and solid phase extractive preconcentration of U(VI) and Th(IV). The “upper-rim” functionalized calix[4]arene-o-vanillinsemicarbazone was covalently linked to Merrifield resin and characterized by FT-IR and elemental analysis. The synthesized chelating polymeric sorbent shows superior binding affinity towards U(VI) and Th(IV) under selective pH conditions. Various physico-chemical parameters that influence the quantitative extraction of metal ions were optimized. The optimum pH range and flow rates for U(VI) and Th(IV) were 6.0-7.0 and 1.0-4.0 ml min−1 and 3.5-4.5 and 1.5-4.0 ml min−1, respectively. The total sorption capacity found for U(VI) and Th(IV) was 48734 and 41175 μg g−1, respectively. Interference studies carried out in the presence of diverse ions and electrolyte species showed quantitative analyte recovery (98-98.5%) with lower limits of detection, 6.14 and 4.29 μg l−1 and high preconcentration factors, 143 and 153 for U(VI) and Th(IV), respectively. The uptake and stripping of these metal ions on the resin were fast, indicating a better accessibility of the metal ions towards the chelating sites. The analytical applicability of the synthesized polymeric sorbent was tested with some synthetic mixtures for the separation of U(VI) and Th(IV) from each other and also from La(III), Cu(II) and Pb(II) by varying the pH and sequential acidic elution. The validity of the proposed method was checked by analyzing these metal ions in natural water samples, monazite sand and standard geological materials. 相似文献
19.
《Monatshefte für Chemie / Chemical Monthly》2010,385(1):829-839
Abstract
The construction, performance, and application of a new PVC membrane electrode for determination of the mercury(II) ion, based on 8,17-bis(pyren-1-ylmethyl)-6,7,8,9,15,16,17,18-octahydrodibenzo[f,m][1,8,4,11]dithiadiazacyclotetradecine as an ionophore, is described. The effects of factors such as membrane composition, the nature and amount of the plasticizers and additives, and pH for the improved sensitivity of the electrode were studied. The electrode had a Nernstian response for mercury(II) ions over the concentration range 1.0 × 10−2–1.0 × 10−6 mol dm−3 with a slope of 27.6 ± 0.6 mV/pHg. The detection limit for mercury(II) was 7.9 × 10−7 mol dm−3. The response time of the electrode was between 5 and 15 s, depending on the concentration of mercury, and it can be used in a pH range 4.0–4.5 for approximately 4 months without any substantial divergence of the response characteristics. It showed higher selectivity for mercury(II) ions than for several common alkali, alkaline earth, and transition metal ions except silver(I). The proposed electrode was successfully applied to direct determination of mercury in a dental filling amalgam alloy as a real sample with a complex matrix and as an indicator electrode in complexation titrations. 相似文献20.
A new ternary ion-association complex of tungsten(VI), 4-nitrocatechol (NC), and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium
bromide (Thiazolyl Blue, MTT) was obtained and studied using an extraction-spectrophotometric method. The optimum pH, reagent
concentrations, and extraction time were determined. The composition of the complex was found to be W(VI): NC: MTT = 1: 2:
2. The extraction process was investigated quantitatively and the key constants were calculated. The molar absorptivity of
the chloroform extract at λmax = 415 nm was 2.8 × 104 dm3 mol−1 cm−1, and the Beer’s law was obeyed up to 8.8 μg cm−3 tungsten(IV). The limit of detection and limit of quantification were calculated to be 0.27 μg cm−3 and 0.92 μg cm−3, respectively. The effect of foreign ions and reagents was studied and a competitive method for determination of tungsten
in products from ferrous metallurgy was developed. The residual standard deviation and the relative error were 0.53 % and
0.2 %, respectively. 相似文献