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1.
Summary To determine total Al in a variety of food and total diet samples using ICP-ES, HF pre-treatment, prior to wet digestion (HNO3/HClO4) seems to be necessary. Compared with results obtained after HF pre-treatment, the determination of Al using pressure microwave digestion with HNO3 or HNO3/HClO4 digestion recovered only between 25–50% Al for dried spinach and flour and 40–75% for total diet samples, respectively. In most cases the addition of 0.25 ml HF (40%) per gram dry mass resulted in maximum Al yield. The results are in acceptable agreement with those obtained by neutron activation analysis (NAA).  相似文献   

2.
Summary For the determination of Se in environmentally relevant materials in the ng/g- and pg/g-range by hydride generation-AAS, H2Se was preconcentrated on Chromosorb W at –150° C prior to its atomization in a silica tube. The individual steps of the procedure — decomposition, reduction of Se(VI) to Se(IV), generation, preconcentration and atomization of H2Se — were optimized, partly using the radioisotope Se-75. Se was determined directly in some water samples, in human hair, finger nails and human serum after decomposition in HNO3/ HClO4 and combustion in oxygen, and in proteins of human serum after isotachophoretic separation and decomposition in HNO3/HClO4. The detection limit of the overall procedure was found to be 6 pg absolute and the linear dynamic range extends to 6 ng.
Bestimmung von Selen im ng/g- und pg/g-Bereich durch Hydrid-Atomabsorptionsspektrometrie in biotischen Matrices
Zusammenfassung Zur Bestimmung von Selen in umweltrelevanten Matrices im ng/g- und pg/g-Bereich durch Hydrid-AAS wurde H2Se auf Chromosorb W bei –150° C vor der Atomisierung in der Quarzküvette angereichert. Die einzelnen Verfahrensschritte — Aufschluß, Reduktion von Se(VI) zu Se(IV), H2Se-Entwicklung, H2Se-Anreicherung und Atomisierung — wurden, teilweise mit dem Radioisotop Se-75, optimiert. Se wurde in einigen Wässern direkt, in Humanhaar, Fingernägeln und Humanserum nach Aufschluß in HNO3/HClO4 und nach Verbrennung im Sauerstoffstrom und in Proteinen von Humanserum nach isotachophoretischer Trennung und Aufschluß in HNO3/ HClO4 bestimmt. Die Nachweisgrenze des gesamten Verfahrens liegt bei 6 pg absolut und der lineare Bereich erstreckt sich bis 6 ng.


Dedicated to Prof. Dr. R. Bock on the occasion of his 70th birthday  相似文献   

3.
A flow-injection analysis atomic absorption spectrometric (FIA-AAS) method was developed for the determination of trace amounts of arsenic, selenium and mercury in a proposed estuarine sediment standard reference material (SRM 1646a). The samples were prepared in two manners: a) A wet digestion procedure with HNO3, H2SO4, and HClO4 using a reflux column and b) A microwave-oven digestion procedure utilizing HNO3, H2SO4, and HCl for As and Se, and HNO3 for Hg. Microwave-oven digestion provides results comparable to those found by reflux column digestion and reduces the sample preparation time by a factor of 10. The proposed method employing the microwave-oven digestion procedure coupled with FIA-AAS for As and Se, and FIA-CVAAS for Hg, has detection limits of 0.15 ng As/ml, O.17 ng Se/ml and 0.15 ng Hg/ml.On leave from the Defense Metallurgical Research Laboratory, Hyderabad, India  相似文献   

4.
Certified reference materials (JMS-2 and JMS-1 – Marine sediment, LKSD-1 Lake Sediment, and STSD-1 Stream Sediment) and bottom sediment were analysed for arsenic by hydride generation atomic absorption spectrometry (HG-AAS) after digestion by different methods (microwave digestion, digestion in aluminium block, dry digestion) and different combinations of acids (HNO3, HCl, HClO4, H2SO4). The study revealed that both wet and dry digestion can be used to digest the reference materials and bottom sediment. Exceptionally satisfactory results were produced by the application of aqua regia, HNO3 + HCl + HClO4, and HNO3 + HCl mixtures. Addition of Mg(NO3)2 during dry digestion caused an increase in arsenic recovery in the reference materials and improved the accuracy of arsenic determination in the bottom sediments.  相似文献   

5.
Summary For the determination of selenium in biological materials the samples are digested with an HNO3/H2SO4/ V2O5 or an HNO3/HClO4 mixture. Selenium is then electrolyzed onto a platinum wire, followed by atomic absorption spectrometry with simultaneous electrothermal and flame atomization. Results for the reference materials Bovine Liver and Albacore Tuna are reported (1–3±0.2 ppm Se).
Selenbestimmung in biologischen Proben durch elektrochemische Anreicherung und Atomabsorptionsspektrometrie
Zusammenfassung Die Proben werden mit HNO3/H2SO4/V2O5 oder HNO3/HClO4 aufgeschlossen; Se wird elektrolytisch auf einem Platindraht niedergeschlagen und durch AAS mit gleichzeitiger elektrothermischer und Flammen-Atomisierung bestimmt. Ergebnisse werden mitgeteilt für die Analyse von Standardreferenzmaterialien (Bovine Liver und Albacore Tuna, 1–3±0,2 ppm Se).
  相似文献   

6.
Summary Isopropyl-N-alkylthiocarbamates have been studied as extractants for preconcentration of silver trace amounts and for separation of silver macroquantities. It has been shown that the 0.05M reagents in chloroform extract trace amounts of silver with high distribution coefficients from HNO3, H2SO4, HClO4 and HCl solutions in wide range of their concentrations. The highest selectivity is obtained when HNO3, H2SO4 or HClO4 solutions are used. Besides silver only mercury and palladium are extracted. When HC1 solutions are used, gold is also transferred into organic phase. Isopropyl-N-alkylthiocarbamates are effective for extraction of silver from its concentrated (up to 1M) solutions, particularly from HNO3 solutions: more than 99.9% of silver is extracted even at 2-fold reagent excess. Some characteristics of reagents themselfes have been investigated, such as dissociation, protonation, distribution between organic and aqueous phases and association in organic solvents. The thion forms are found to be predominant. Silver is extracted as coordination solvated compounds Ag(HL) n X, where X=Cl, Br, J, NO3. Sulfur serves as a donor atom for their formation.The procedures for silver determination in geological samples by flame atomic absorption (3×10–7%) and atomic emission (1×10–7%) have been developed. The procedures for atomic emission determination of 23 trace elements (5×10–8–1×10–5%) and for electrothermal atomic absorption determination of 17 trace elements (4×10–9–8×10–6%) in high purity silver have also been developed.
Neue wirksame und selektive Extraktionsmittel für die Trennung und Bestimmung von Silber
Zusammenfassung Isopropyl-N-alkylthiocarbamate wurden als Extraktionsmittel für die Anreicherung von Silberspuren und für die Abtrennung von Makromengen Silber geprüft. Es ergab sich, daß solche 0,05M, in Chloroform gelöste Reagenzien Silberspuren mit hohen Verteilungskoeffizienten aus HNO3, H2SO4, HClO4 und HCl extrahieren. Die beste Selektivität wurde mit HNO3, H2SO4 oder HClO4erzielt. Neben Silber werden nur Quecksilber und Palladium extrahiert. Verwendet man HCl, so geht auch Gold in die organische Phase. Isopropyl-N-alkylthiocarbamate eignen sich für die Extraktion von Silber aus konzentrierten (bis zu 1M) Lösungen, besonders aus HNO3: mehr als 99,9% Silber werden mit zweifachem Reagensüberschuß extrahiert. Einige charakteristische Eigenschaften der in Rede stehenden Reagenzien wurden untersucht: z. B. die Dissoziation, die Protonation, die Verteilung zwischen organischer und wäßriger Phase und die Assoziation in organischen Lösungsmitteln. Hauptsächlich liegen diese Reagenzien in Thionform vor. Silber wird als Ag(HL) n X extrahiert, worin X für Cl, Br, J oder NO3 steht. Schwefel fungiert als Donatoratom für deren Bildung.Verfahren zur Silberbestimmung in geologischen Proben mit Hilfe der Flammen-Atomabsorption (3×10–7%) bzw. der atomaren Emission (l×10–7) wurden ausgearbeitet. Außerdem wurden auch Verfahren zur Bestimmung von 23 Spurenelementen mittels atomarer Emission (5×10–8 bis 1×10–5%) und von 17 Spurenelementen mittels elektrothermaler Atomabsorption (4×10–9 bis 8×10–6%) in hochgereinigtem Silber entwickelt.


The paper has been presented at the Fifth European Conference on Analytical Chemistry (Euroanalysis V), Cracow, August 26–31, 1984.  相似文献   

7.
The order of extraction of Mo(VI) from 1M acid solutions by 5% (v/v) LIX 622 (HL) in benzene is HCl>HNO3>HClO4>H2SO4, and extraction decreases with increasing concentration of HCl and H2SO4, and increases slightly with increasing concentration of HNO3 and HClO4. The extracted species is shown to be MoO2L2 as established by IR data of organic extracts and the extracted species in the solid form. Extraction is almost quantitative at and above 10% LIX 622, and is found to be independent of [Mo(VI)] in the range of 10–4 to 10–3 M. The diluents CCl4, CHCl3 and C6H6 are found to be superior to solvents of high dielectric constant for extraction of Mo(VI). Extraction of uranium(VI) by 10% (v/v) LIX 622 in benzene was found to increase with increasing equilibrium pH (3.0 to 6.0), and becomes quantitative at pH 5.9. Tributyl phosphate acts as a modifier up to 2% (v/v). Thorium(IV) is almost not extracted by LIX 622 or its mixture. Separation of Mo(VI) and U(VI) is feasible.  相似文献   

8.
The structure of the H3O+ ion embedded in a solid environment (H3O+X, X = Cl, NO 3 , ClO 4 ) is studied using a modified version of CNDO/2. In this calculation the effect of the first shells of nearest neighbours is taken into account and the effects of second nearest neighbours are introduced by a simulation procedure. Electronic effects are also included. The ion structure is more planar in nitrate than in perchlorate environment and the hydrogen bonds are slightly bent. Trends in structural parameters are compared with chemical properties of the hydrogen bonds and parallels the Hammett acidity scale HNO3 < HCl < HClO4.  相似文献   

9.
Different methods for the determination of several metals in soils by flame atomic absorption spectrometry (FAAS) were investigated. Different procedures for total dissolution of soil: I – HF+HClO4, H3BO3, HCl digestion (conventional heating), II – HF+HClO4, H3BO3 digestion followed by fusion with LiBO2 (conventional heating) and III – HF+HCl+HNO3, H3BO3 digestion (microwave heating), as well as a leaching procedure with HNO3+HClO4, HCl were tested and compared. For quality assessment, the certified reference material S-1 soil was used. For most of the investigated metals, the best accuracy and precision were achieved when the procedure I or III were used. The developed procedure was applied to the analysis of soil samples from crude oil refinery and dump of petroleum origin wastes regions. Received: 22 Dezember 1997 / Revised: 9 February 1998 / Accepted: 12 February 1998  相似文献   

10.
Total arsenic in nine species Antarctic macro algae has been measured, by electrothermal atomic absorption spectrometry using a Pd/Mg(NO3)2 matrix modifier, to determine their capacity to accumulate the element. Macro algae were collected in February during the 2000 austral summer season at Jubany Station (Argentinean scientific station) around Potter Cove, King George Island. An optimized two-step microwave (MW) program was used to digest the samples. Dried samples were treated with HNO3, H2O2, and HF, left overnight, then subjected to the first MW cycle. After cooling HNO3 and HClO4 were added and samples were subjected to the second MW cycle of digestion treatment. The effect of power and time on As recovery was examined. The analytical features of the method were: detection limit, 0.24 g g–1 (dry mass); precision (RSD), 4.2–5.7%; recovery 91–105%. A wide range of As-retention capacity (41.0–447 g g–1 dry mass) was observed among the different species. The highest levels of As were found in Phaeurus antarcticus (447 g g–1 dry mass). This organism satisfies several prerequisites to be considered for consideration as a biomonitor in future studies.  相似文献   

11.
An analytical method has been developed for the determination of low-level99Tc in environmental samples by High Resolution ICP-MS. The method consists of leaching of99Tc by HNO3 and separation by three different solvent extractions with 30% TOA-xylene, MEK, and cyclohexanone. Finally, purification of99Tc was made by using an anion exchange resin column to reduce dissolved solids content. The final solution was adjusted to 1M HNO3 for introducing into the HR-ICP-MS. The accuracy and precision of the method was confirmed to be satisfactory by applying this technique to the determination of99Tc in IAEA marine algae sample (AG-B-1). Measurements of99Tc using 0.5–2.5 g of sediment samples from the Irish Sea, UK, were successfully performed by the present method.  相似文献   

12.
The oxidation of americium in HNO3, H2SO4 and HClO4 solutions by a mixture of potassium persulfate with silver salt in the presence of potassium phosphotungstate has been investigated. The influence of acid and its concentration, of (NH4)2S2O3, K10P2W17O61 and silver salt on Am(III) oxidation rate, yield and stability of Am(IV) and Am(VI), has been studied. The complexation of Am(III), Am(IV) and Am(VI) with phosphotungstate ions has been investigated. It has been established that Am(III) and Am(IV) form ML2 complexes and their apparent stability constants have been estimated. The oxidation mechanism is discussed. A method for preparing of Am(IV) in 0.1–6M HNO3, O.1–3M H2SO4, 0.1–1M HClO4 solutions is proposed. The oxidation of Am(III) to Am(IV) by KBrO3 and K2Cr2O7 in HNO3, H2SO4, HClO4 solutions in the presence of K10P2W17O61 has been investigated.  相似文献   

13.
Summary A sensitive spectrofluorimetric method is based on the complexation of Al with the dye Mordant Black 17 or Calcon (CI 15705). The complex solution in n-propyl alcohol (1.5×10–4 mol/l) is mixed (5:20) with 1 mol/l acetic acid — sodium acetate buffer (pH 4.8) and maintained at 40°C for 60 min. The fluorescence intensity is measured at Ex=565 nm, Em=610 nm: The calibration curve for Al was found to be linear in the range 0 to 60 ng×ml–1 with a standard deviation of =1.5 and an Al detection limit of 3 ng×ml–1. The interferences due to more than 40 ions were investigated; the presence of Fe3+, Cr3+, Co2+, Cu2+, Ti4+, VO2+, ZrO2+, WO 4 2– , MoO 4 2– , CrO 4 2– and particularly F, must be avoided or masked during the determination of Al. The sample of silicon/silicon dioxide was treated with a mixture of conc. HF and HNO3 (2:1), followed by digestion and distillation at 90°C to eliminate the matrix as fluorosilicic acid. A small residue of AlF3 was decomposed with HClO4. In SiO2 anodized layers (25–250 g) the minimum detection of Al was estimated to be 1018 At×cm–3, in monocrystalline silicon (25–250 mg) 1016 At×cm–3. The method can also be employed to determine the presence of Al in the residues by distillation of a small quantity (5–10g) of many solvents or reagent solutions. Presented at: IX. Congresso Nazionale — Div Chim Anal (S.C.I.) Ferrara 1990  相似文献   

14.
Extraction of WO 4 2– and ReO 4 by Adogen-381, tricaprylmethylammonium chloride, Hyamine 10-X, trioctylphosphine oxide or dibenzylsulphoxide in xylene from HNO3, HCl or H2SO4 acid medium was investigated. Based on the separation factors obtained, the separation of ReO 4 from WO 4 2– was elucidated. ReO 4 was separated from WO 4 2– in high radiochemical purity: >99.9% by three successive extractions and strippings using Adogen-381 from HCl or HNO3 acid medium.  相似文献   

15.
Five closed-vessel microwave digestion methods were compared for the accurate determination of arsenic and selenium in NIST SRM 1645 River Sediment by flow-injection hydride-generation atomic absorption spectrometric methods. The digestion methods using five different acid mixtures (HNO3/ H2SO4, HNO3/HCl04, HNO3/HCl, HNO3/HCl/HF, HNO3/H2SO4/HClO4) were all found to be reliable for the determination of the analytes. Taking into consideration the safety and suitability for the analysis of other metals, the methods based on the use ofaqua regia are recommended for closed vessel microwave digestion with pressure control. Using the quick digestion program, the presence of up to 10% organic content in soil samples did not adversely affect the closed vessel digestion and did not cause the loss of volatile analytes. After digestion, opening the vessel under an inner pressure of below 345 kPa (50 psi) had no effect on the accuracy of the results. The recommended digestion methods (HNO3/HCl and HNO3/ HCl/HF) for the reliable determination of arsenic and selenium in different sediment samples were demonstrated. The calculated detection limits (3 b ) were less than 0.030 g/g and 0.033 g/g for arsenic and selenium, respectively. All analytical results for arsenic and selenium in SRM 1645 River sediment, NRCC BCSS-1 Marine Sediment and NIES CRM Pond Sediment were within or near the certified and reported ranges, with the exception of selenium in NIES CRM No. 2 Pond Sediment.  相似文献   

16.
Extraction, loading and stripping studies of Pu(IV) have been carried out using three phosphine oxides namely CyanexÒ-923 (cyn-923), CyanexÒ-925 (cyn-925) and TOPO in dodecane from nitric acid medium. All the three phosphine oxides have shown very high extraction of Pu. The order of extraction for Pu by these compounds is cyn-923 > TOPO - cyn-925. Loading of Pu (30.0 mg/l) in 3.0M HNO3 was carried out using 5% solution of each of the phosphine oxides in dodecane. It was found that even at an organic to aqueous phase ratio of 1:10, the loading of Pu is >96%. From the loaded organic phase, Pu could be almost quantitatively stripped using 0.1 or 0.5M oxalic acid. The extraction of Pu(IV) with cyn-925 has also been carried out from HCl, HNO3 or HClO4 (0.5 to 9.1M). The species extracted into the cyn-925/dodecane phase from 3.0M HNO3 or HCl media was found to be Pu(L)4 .2 cyn-925 where L = NO3 or Cl. Similar species were observed to be formed when dodecane was replaced by xylene, chlorobenzene or o-dichlorobenzene.  相似文献   

17.
Different methods for the determination of several metals in soils by flame atomic absorption spectrometry (FAAS) were investigated. Different procedures for total dissolution of soil: I – HF+HClO4, H3BO3, HCl digestion (conventional heating), II – HF+HClO4, H3BO3 digestion followed by fusion with LiBO2 (conventional heating) and III – HF+HCl+HNO3, H3BO3 digestion (microwave heating), as well as a leaching procedure with HNO3+HClO4, HCl were tested and compared. For quality assessment, the certified reference material S-1 soil was used. For most of the investigated metals, the best accuracy and precision were achieved when the procedure I or III were used. The developed procedure was applied to the analysis of soil samples from crude oil refinery and dump of petroleum origin wastes regions.  相似文献   

18.
175, 181Hafnium(IV) was extracted by HDBP in 2-ethylhexanol from 1–10M solutions of HClO4, HCl and HNO3, and 1–8M H2SO4. As with low polar organic phase diluents, the acidity dependence of the distribution ratio of Hf, D, passes through a minimum for HClO4, HCl, and H2SO4 whereas only an increase of D can be observed with increasing HNO3 concentration. From the slope analysis the following complexes were found to be extracted (HDBP=HA): HfA4 at <4M HClO4 and <5M HCl, lg Kextr=9, HfX4(HA)4 (X=ClO 4 , Cl or NO 3 ) at >5M HClO4, >7M HCl and 1–10M HNO3, Hf(SO4)A2(HA)3–4 at <3M H2SO4, and Hf(SO4)2 (HA)4 at >6M H2SO4. Coextraction of sulphate with hafnium from H2SO4 solutions was evidenced in experiments with macro concentrations of Hf(IV) and35SO 4 2− . Part XX: Coll. Czech. Chem. Commun., 40 (1975) 3617.  相似文献   

19.
An increase of the 2nd polarographic uranium(VI) wave has been observed in the presence of chlorate ions in HClO4–NaClO4, or HClO4–NaClO4–NaCl supporting electrolyte, resp. The polarographic measurements at different temperatures and at various perchloric acid concentrations show that this increase is due to a kinetic U(III)-U(IV) current. The activation parameters of the U(III)-U(IV) oxidation reaction with ClO3 have been calculated usingKautecky's method.The approximately 5fold increase of the 2nd polarographic wave allows the determination of small amounts of uranium (10–5–10–6 mole/l).

Mit 2 Abbildungen  相似文献   

20.
A new simple method for the simultaneous determination of59Fe and55Fe concentration in 5 ml samples of blood is described and carefully evaluated. Before the measurement of the activity of the radionuclides, organic matter was eliminated by HNO3?HClO4 wet ashing. Iron was electroplated onto a copper plate. The accuracy of results was studied by assessing samples, which contained known amounts of radioactivity and determining the counts per nanocurie in each case. The accuracy of the results of59Fe and55Fe determinations was found to be about 5%.  相似文献   

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