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1.
A sequential extraction procedure for waste water sediments was elaborated based on CO2 and water extractants using supercritical fluid extraction instrumentation. The procedure gives information on water-soluble, carbonate-bound and mobile organic-bound trace metal fractions. The chemical interpretation of this procedure is comparable with the BCR recommended three-stage sequential extraction. The validation of the proposed procedure requires more detailed investigations. 相似文献
2.
María Ramos-Payán Rut Fernández-Torres Juan Luis Pérez-Bernal Manuel Callejón-Mochón Miguel Ángel Bello-López 《Analytica chimica acta》2014
A novel approach based on the use of nanometallic-decorated hollow fibers to assist electromembrane extraction is proposed. Microporous polypropylene hollow fibers, on which nanometallic silver was deposited, have been used for the first time as liquid membrane support in electromembrane extraction (EME). Different methods for the generation/deposition of silver nanoparticles (AgNPs) were studied. The best results were obtained with chemical reduction of silver nitrate using NaBH4 in aqueous solution followed by direct deposition on the hollow fibers. The extraction performance of the new supports was compared with a previously developed EME procedure used for the extraction of selected non-steroidal anti-inflammatory drugs (NSAIDs), resulting in an increase in the extraction ratio by a factor of 1.2–2 with a 30% reduction in the extraction time. The new nanometallic-decorated supports open new possibilities for EME due to the singular properties of nanometallic particles, including chemical fiber functionalization. 相似文献
3.
Role of Cyanex-272 as an extractant for uranium in the determination of rare earths by ICP-AES 总被引:2,自引:0,他引:2
B. Rajeswari B. A. Dhawale T. R. Bangia J. N. Mathur A. G. Page 《Journal of Radioanalytical and Nuclear Chemistry》2002,254(3):479-483
A chemical separation procedure has been developed for the extraction of uranium from some of the crucially important rare earths using a novel extractant viz. Cyanex-272 (2,4,4-trimethyl pentyl phosphinic acid). The near total extraction of uranium and quantitative separation of rare earth elements has been validated using inductively coupled argon plasma - atomic emission spectrometry (ICP-AES). The recovery of some of the representative elements has been confirmed by radioactive tracer studies. The back extraction of uranium from the organic phase was carried out using a solution of 0.5M Na2CO3 which resulted in a near total recovery of uranium into the organic phase. These studies have enabled determination of sub ppm amounts of the analyte elements with a precision of 5% RSD utilizing prior chemical separation of rare earths from 1 g uranium samples in just three extractions with Cyanex-272. 相似文献
4.
R. S. Sidhu 《Journal of Radioanalytical and Nuclear Chemistry》2003,256(3):501-504
A new procedure for the analysis of Pu and Am in large water samples is presented. In this procedure, the actinides are first preconcentrated from 200 liter water samples with combined MnO2 and Fe(OH)3 co-precipitation. Pu and Am are then separated from the large amount of Mn by performing a second precipitation of Fe(OH)3 at pH 6. The final separation of Pu and Am from interfering elements and from each other is achieved with the use of a single extraction chromatographic column of TRU-ResinÔ. The -activities are then determined using -spectrometry after source preparation by CeF3 micro co-precipitation. The procedure described is faster, simpler, more robust and gives higher chemical yields then procedures normally used for routine analysis of Pu and Am. The chemical yields of Pu and Am, when analysing 200 liter sea water samples, are between 80-85%. 相似文献
5.
Ihsanullah J. Akhter A. Rauf M. A. Atta 《Journal of Radioanalytical and Nuclear Chemistry》1999,240(1):293-296
A comprehensive radiochemical procedure for the measurement of gamma/beta activity of131I has been standarized by optimizing different steps. The procedure is mainly divided into three stages, i.e., (1) concentration
of iodine using anion exchange column followed by elution; (2) extraction of iodine into CCl4 and back extraction, and (3) precipitation as AgI. The percent chemical recovery and the lower limit of detection (LLD) were
found to be 75.5±5% and 0.014 mBq/ml, respectively. 相似文献
6.
By using 188Re as a radiotracer, the extraction behavior of Re(VII) by a tertiary amine extractant N-235 from HCl and the back-extraction behavior of Re(VII) by HNO3 and ammonia were studied. A chemical separation procedure, which combined the acid alumina column and solvent extraction was established. The procedure was rapid and efficient for the separation of 186Re from 186W irradiated by 16 MeV deuterons. No-carrier-added 186ReO4
– saline solution with high specific volume activity was obtained. The overall recovery yield of 186Re was about 85%. 相似文献
7.
A radiochemical procedure is described for the fast and sensitive measurement of uranium isotopes in gaseous and liquid effluents of nuclear facilities. Equally, this procedure is suitable to measure uranium isotopes in all kinds of environmental samples. Uranium is leached from ashed sample materials with HNO3, HF, and Al(NO3)3 solution and separated from matrix elements by extraction with trioctylphosphinic oxide and backextraction with NH4F. After radiochemical cleaning by coprecipitation with LaF3 and anion exchange, uranium isotopes are electroplated on stainless steel discs from HCl/oxalate solution. The preparation is measured by alpha-spectrometry using surface barrier detectors. The detection limit for 1000 minutes of counting time is 2 mBq per sample and nuclide, the chemical yield is in the range of 50 to 80%. 相似文献
8.
《Analytical letters》2012,45(20):1745-1756
Abstract A chemical ionization and an electron impact GC/MS assaying approach is presented for determining dibucaine concentrations in biological fluids. Both use deuterium-labeled drug as the internal standard and rely on the same sample extraction and sample preparation procedure. Under chemical ionization conditions (CH4), the assaying limits are in the range of 1–80 ng/ml of serum. Under electron impact conditions, the analytical range is 20–800 ng/ml. The chemical ionization procedure has been found suitable for monitoring drug levels in man. One volunteer, who received a single 5-mg oral dose, showed peak serum drug concentrations of 23 ng/ml attained 2 hr after drug administration. The biologic half-life (ß phase) was 11 hr. 相似文献
9.
The purpose of this research was to develop an optimized pretreatment procedure for toxic metals (Pb, Cd, Zn and Cu) content in fly ash from a municipal waste incinerator. In addition, modified sequential extraction procedures were used to characterize the chemical composition of the fly ash samples. The sequential extraction resolved the fly ash elements into the following chemical forms: soluble, exchangeable, carbonate, oxide, organic, and silicate compounds. Certified reference city waste incineration ash (BCR.176) was used as target ash samples. A H2O2+HNO3+HF mixed acid digestion solution with a low temperature evaporation procedure was selected as optimal for the fly ash digestion. The digested solution was analyzed by inductively coupled plasma mass spectrometry (ICP‐MS), which effectively determined the concentrations of the toxic metal elements in BCR.176. Except for Cd, the recovery of Pb, Zn, and Cu under H2O2+HNO3+HF digestion and their sequential extraction procedures were higher than 95%. The relative standard deviations (RSD) for recoveries of the four elements were within 10%. Furthermore, the sequential extraction procedure's results provided information on the potential mobility of the studied elements. Most of the Cd was bound to water‐soluble and carbonate material in the fly ash samples. Most of the Pb, Zn, and Cu was released to carbonates and bound to organic matter in the fly ash samples. 相似文献
10.
Elemental fractionation of Si, Al, Ti, Fe, Ca, Mn, P, and Ba in five marine sedimentary reference materials: results from sequential extractions 总被引:1,自引:0,他引:1
We report on the elemental results from sequential extractions of BCSS-1 (marine sediment), MESS-1 (estuarine sediment), MAG-1 (marine mud), SCo-1 (Cody shale), and NIST-1c (argillaceous limestone) to encourage future comparisons of sequential extraction results within the marine geochemical and paleoceanographic communities. We measured Si, Al, Ti, Fe, Mn, Ca, P, and Ba in sequential de-ionized water (loosely-bound), MgCl2 (exchangeable), acetic acid (carbonate), hydroxylammonium hydrochloride (oxide), H2O2 (organic), Na2CO3 (opal), and residual (lithogenic) leaches. The protocol and selected elements were tailored to be most relevant to paleoceanographic geochemical studies instead of to environmental studies. Our results show that the sequential extraction procedure faithfully yields elemental distributions that are consistent with individual SRM lithologies. Our results also show that the procedure is typically reproducible within approximately 15%. However, in almost all cases, the procedure suffers from a systematic under-recovery of material when compared with the certified, bulk chemical analysis, and the under-recovery appears to be related to the lithology of the SRM. Similar under-recovery appears to be typical of sequential extraction procedures as reported by other previous studies. While this is problematic in assessing closure, it does not diminish the potential of inter-lab comparisons and first-order accuracy comparisons. We found that the elemental totals for the sequential extractions of MAG-1 compared best with the certified, bulk totals, and we recommend using this SRM to facilitate future accuracy assessments and inter-lab comparisons. 相似文献
11.
The extraction of nitrophenols with polymethine dyes of the common formula R1-(CH=CH)3-R2, indolium and benzothiazolium derivatives was studied. The effect of the acidity of the solution, the nature and the concentration of the dye, and the nature of the organic solvent on the formation and extraction of ion pairs of nitrophenols was examined; the optimum conditions were found. The most important chemical analytical characteristics of the ion pairs were determined. Molar absorptivities of extracts are 11.9 × 104–14.3 × 104 for ion pairs of trinitrophenol and 6.8 × 104–10.1 × 104 for ion pairs of dinitrophenol. A new procedure was developed for the extraction-photometric determination of nitrophenols in a mixture. 相似文献
12.
F. M. G. Tack M. G. Verloo 《International journal of environmental analytical chemistry》2013,93(1-4):167-175
Abstract A contaminated dredged sediment was subjected to a thermal treatment at temperatures ranging from 120 to 450°C. The leaching behaviour of selected metals (Cd, Cu, Pb, Zn, Fe, Mn) was studied using NH4OAc-EDTA extraction. In addition, solid phase fractionation was carried out by means of a sequential extraction procedure. The NH4OAc-EDTA extraction showed a sharp increase in metal leachability from sediments treated at intermediate temperatures (120–350°C). The metal fractionation of the solid phases at the different temperatures did not reveal relevant shifts except for Cu. The decrease of the oxidizable Cu fraction was highly correlated (P < 0.001) with the disappearance of organic matter at higher treatment temperatures. It is suggested that binding energy changes within the fractions rather than shifts between chemical forms account for the observed leaching behaviour. 相似文献
13.
Chen Qing-Jiang A. Aarkrog H. Dahlgaard S. P. Nielsen E. Holm H. Dick K. Mandrup 《Journal of Radioanalytical and Nuclear Chemistry》1989,131(1):171-187
Distribution coefficients of technetium and ruthenium are determined under different conditions with CCl4, cyclohexanone, and 5% tri-isooctylamine (TIOA)/xylene. A method for analyzing99Tc in environmental samples has been developed by solvent extraction in which the valences of technetium and ruthenium are controlled with H2O2 and NaClO. Technetium and ruthenium which are oxidized to TcO
4
–
and RuO
4
–
by NaClO are separated by extraction with CCl4 at pH 4. The RuO
4
–
is reduced to low valence and technetium is kept in the TcO
4
–
state with H2O2. Technetium, ruthenium, and other nuclides are subsequently separated by solvent extraction with cyclohexanone and 5% TIOA/xylene. The decontamination of the procedure is 1.35·105 for103Ru and 1.66·105 for110mAg. The chemical yield of technetium-99 is 55%.On leave from Institute of Atomic Energy, Beijing, China 相似文献
14.
Determination of total PCB and dioxin by activation analysis 总被引:1,自引:0,他引:1
H. Förster W. Görner P. Strempel 《Journal of Radioanalytical and Nuclear Chemistry》1995,192(2):299-305
The analysis of PCB's and dioxins in water by activation with high energy photons is described. The substances were traced by heterochlorine. PCB and dioxins were separated selectively in the presence of a biphenyl-dibenzofurane mixture as a collector by extraction with hexane. Polar compounds were rinsed out, and chloroalkyles were evaporated. After exposure of the collector to 30 MeV bremsstrahlung it was decomposed following the Schöniger procedure. The chemical yield was measured through activity counting of11C separated as11CO2 from the collecting agent, in comparison with a reference material. The chlorine yield was determined gravimetrically using a stoichiometrically well-determined reference material. A few nanograms of chlorine per millilitre are detectable whereby primary samples of 1 l or more may be treated. The described procedure can be recommended as a reference technique for analyses via chromatography/mass spectrometry. Simultaneous analyses of other halogens are planned. 相似文献
15.
Xiaowei Yi Yanmei Shi Jiang Xu Xiaobing He Haitao Zhang Jianfeng Lin 《Journal of Radioanalytical and Nuclear Chemistry》2013,298(3):1757-1761
A radiochemical procedure is developed for the determination of 237Np in soil with multi-collector inductively-coupled plasma mass spectrometry (MC-ICP-MS) and gamma-spectrometry. 239Np (milked from 243Am) was used as an isotopic tracer for chemical yield determination. The neptunium in the soil is separated by thenoyl-trifluoracetone extraction from 1 M HNO3 solution after reducing Np to Np(IV) with ferrous sulfamate, and then purified with Dowex 1 × 2 anion exchange resin. 239Np in the resulting solution is measured with gamma-spectrometry for chemical yield determination while the 237Np is measured with MC-ICP-MS. Measurement results for soil samples are presented together with those for two reference samples. By comparing the determined value with the reference value of the 237Np activity concentration, the feasibility of the procedure was validated. 相似文献
16.
The possibilities of radiostrontium extraction from milk after the isolation of radiocesium were investigated. The polyhedral
complex of the type H+[(π-/3/-1,2-C2B9H11)2Co−], further referred to as dicarbolide-H+, in nitrobenzene was used for the extraction. The increase of values and larger differentiation of distribution ratios in
the extraction of ion associates of radionuclides were achieved by hydrophobizing with polyethyleneglycol (PEG). The changes
of the distribution ratios of90Sr,89Sr and90Y with PEG concentration were studied, and ranges of the highest synergic effect, changing with different extraction agent
concentrations in extraction from water solutions and a fresh milk were determined. The influence of milk dilution and nitric
acid concentration upon the value of distribution ratio in radiostrontium extraction using dicarbolide-H+ and the optimum PEG concentration were investigated. Under suitably selected conditions of radiostrontium isolation, the
distribution ratios of some potential contaminants were determined. The influence of nonisotopic carrier Ca2+ upon radiostrontium extraction was examined. The possibilities of purification of isolated radiostrontium using reextraction
were investigated. A selective and quick analytical procedure was suggested for radiostrontium isolation after the separation
of radiocesium from a mixture of fission and activated radionuclides in milk using extraction by dicarbolide-H+. The chemical yield is about 98% and90Sr is determined by liquid scintillation technique. 相似文献
17.
T. A. Kuchmenko E. V. Drozdova A. A. Shuba E. I. Samoilova 《Russian Journal of General Chemistry》2016,86(13):2951-2960
A procedure has been proposed for express assessment of the degree of pollution of melt and snow waters with volatile aromatic compounds using a set of chemical sensors. The number of measuring units has been minimized to 2 for the yes/no detection (alarm system) of volatile aromatic toxicants in natural waters of different salinities. An algorithm has been developed for the extraction of analytical information on the presence of volatile compounds or salts in meltwater by the sorption efficiency parameters A ij and their profiles (petal diagrams) or by cluster analysis. 相似文献
18.
Ning Chen Xiaolin Hou Weijian Zhou Yukun Fan Qi Liu 《Journal of Radioanalytical and Nuclear Chemistry》2014,299(3):1965-1971
An improved solvent extraction procedure for iodine separation from brine samples has been applied at Xi’an Accelerator Mass Spectrometry (AMS) center. Oil in the brine sample has to be removed to avoid appearance of the third phase during solvent extraction and to improve the chemical yield of iodine. The small amount of oil remained in the water phase was first removed by phase separation through settling down sufficiently based on their immiscibility, and then by filtration through a cellulose filter, on which oil was absorbed and removed. After oil removed, extraction recovery of iodine could achieve more than 90 %. The sodium bisulfite as an effective reductant should be added before acidification to avoid loss of iodine by formation of I2 in sample via reaction of iodate and iodide at pH 1–2, and then pH was adjusted to 1–2 to reduce the iodate to iodide followed by oxidation of iodide to I2 and solvent extraction to separate all inorganic iodine. As a pre-nuclear era sample, 129I/127I ratio in brine is normally more than two orders of magnitude lower than that in present surface environmental samples, so prevention of cross-contamination and memory effect in apparatus during processing procedure are very critical for obtaining reliable results, and monitoring the procedure blank is very important for analytical quality of 129I. The 129I/127I isotopic ratio in the brine samples and procedure blank of iodine reagents were measured to be (1.9–2.7) × 10?13 and 2.08 × 10?13, respectively, 3–4 orders of magnitudes lower than that in environmental samples in Xi’an, and the result of procedure blank is in the same level as the previous experiments in past 3 years, indicating contamination is not observed in our method. 相似文献
19.
20.
Y. Cai G. Tang R. Jaffé R. Jones 《International journal of environmental analytical chemistry》2013,93(3):331-345
Abstract Three extraction methods, acidic KBr/CuSO4 isolation-methylene chloride extraction. acidic KBr/CuSo4 isolation-methylene chloride extraction with an alkaline digestion pretreatment, and an extration method at a milder condition with citrate buffer and dithizone in chloroform, were studied for methylmercury and ethylmercury determination in soils, sediments and fish samples by the recently developed capillary gas chromatography—atomic fluorescence spectrometry system (GC-AFS). The acidic KBr/CuSO4-methylene chloride extraction and the acidic KBr/CuSO4-methylene chloride extraction with an alkaline digestion pretreatment were shown to be the effective methods for soils/sediments and fish samples analysis, respectively. The presence of ethylmercury species in soils of the Florida Everglades, observed with the acidic KBr/CuSO4 isolation and methylene chloride extraction procedure, was further confirmed with the dithizone complexation/extraction procedure. The GC-AFS analytical method offers high senstivity and selectivity for the determination of organomercury halides. The GC column maintenance, a critical step for organomercury halides analysis using GC, is also discussed. 相似文献