共查询到20条相似文献,搜索用时 15 毫秒
1.
Héctor Hernández-Mendoza Abel Yllera 《Journal of Radioanalytical and Nuclear Chemistry》2013,298(2):1417-1420
Two extraction processes of plutonium (Pu) on planchets from alpha spectrometry (AS) have been evaluated by inductively coupled plasma sector field mass spectrometry with a desolvator system (Aridus–ICP–SFMS). The samples were traced with known concentrations of 239Pu (1.2 × 103 fg) and 242Pu (2 × 103 fg) followed by an electrodeposition in planchets, according to the Hallstadius method. The processes of extraction were carried out with 50 mL of 0.36 mol L?1 HNO3 every 30 min up to 180 min in a glass beaker at 60 °C. The first process was on a hotplate and the second used an ultrasonic system. Finally, samples were evaporated to dryness, and resuspended in 10 mL of 0.72 mol L?1 HNO3 for evaluation. The results showed that at 120 min, a ~70 % recovery of 239Pu and a ~80 % recovery of 242Pu in both processes were obtained. The average recoveries of 239Pu and 242Pu at 180 min using the hotplate in plate were 93.4 ± 4.6 and 93.7 ± 4.2 % respectively, and with the ultrasonic system were 96.0 ± 4.3 and 98.2 ± 1.0 % respectively. In conclusion, both processes are suitable for Pu extraction, and Aridus–ICP–SFMS is an essential technique for the reassessments and quantification of Pu. In addition, procedural blanks spiked with 1 × 102 fg mL?1 U were prepared for each process, in order to study the contribution of the 238U on the background signal at m/z = 239, which was 0.5 ± 0.2 cps, indicating that the contribution of 238U on the 239Pu signal was negligible. Furthermore, this methodology can be applied to sample planchets with environmental, food, biological and nuclear origin, and thereby to avoid repetitive analysis when Pu concentration determined by AS are under minimum detectable activities. 相似文献
2.
Mueller-Spitz SR Vonderheide AP Shann JR Caruso JA Kinkle BK 《Analytical and bioanalytical chemistry》2006,386(1):142-151
The potential of chromium to bind to DNA isolated directly from soil microbial communities was investigated in this study.
An analytical scheme was developed to distinguish between chromium bound to DNA and its fragments or chromium contained elsewhere
in an environmental DNA extract. DNA was extracted from chromium-contaminated soils and purified using DNA clean-up resins.
Size-exclusion chromatography was employed due to its advantages in the separation and molecular weight approximation of large
biomolecules. It was coupled with two on-line detection systems (spectrophotometric and inductively coupled plasma mass spectrometric)
to study the binding of chromium to DNA or other components in a DNA extract. A collision cell was pressurized with helium
to remove diatomic and polyatomic interferents resulting from the chosen mobile phase. Chromium peaks were observed in both
the large and small molecular weight regions of the chromatogram; to further confirm that the environmentally extracted DNA
contained Cr, the subsequently purified DNA was examined for total Cr using flow injection ICP–MS to accommodate small sample
volumes. DNA samples isolated from the two soils examined contained 0.5–0.7 ppb Cr, indicating that DNA isolated directly
from a chromium-contaminated soil has chromium bound to the nucleic acids. 相似文献
3.
Absolute protein quantification has become an important challenge in modern bioanalytical chemistry. Among several approaches
based on mass spectrometric techniques, inductively coupled plasma (ICP) as ionisation source provides element-selective and
sensitive detection of heteroatoms, and thus, a potentially emerging tool in protein analysis. In this work we applied coupling
of capillary liquid chromatography (μLC) and inductively coupled plasma-sector field mass spectrometry (ICP–SFMS) to the separation
and determination of standard proteins. For quantification purposes, post-column isotope dilution of sulfur was applied and
optimised for this type of hyphenated technique. Provided that the protein sequence is known (number of sulfur-containing
amino acids, i.e. cysteines and methionines) the protein amount can then be directly calculated from the determined sulfur
content in a certain protein fraction. In order to prove the reliability of the presented method, two different certified
reference materials were analysed: CRM 393 (human apolipoprotein A-I) and CRM 486 (α-fetoprotein). For CRM 393 excellent agreement
(37.0 ± 1.4 μmol L−1) was obtained with the certificate (37.7 ± 1.8 μmol L−1). However, the recovery rate for α-fetoprotein in CRM 486 was found to be about 60% indicating incomplete elution of the
protein during the chromatographic separation. 相似文献
4.
《Colloids and surfaces. B, Biointerfaces》2003,27(2-3):209-213
The membranes of polydiacetylene backbone decorated with mannose assembled by Langmuir–Blodgett technology can interact with Escherichia coli. The interactions lead to the color transition of the membranes which was readily visible to the naked eyes and could be quantified by visible absorption spectroscopy. To understand the mechanism of the chromatic transition, the affinochromism properties of polydiacetylene were examined by resonance Raman spectroscopy. The results demonstrated that the side chains of polymer backbone performed rearrangement, and the electronic structure in the polymer backbone changed from acetylene to butatriene form when the chromatic transformation from blue to red. The direct colorimetric detection by polydiacetylene membranes not only opens a new path for the use of these membranes in the area of biosensor development but also offers new possibilities for diagnostic applications and screening for binding ligand. 相似文献
5.
《Trends in analytical chemistry : TRAC》2001,20(6-7):274-287
Ion chromatography (IC) and atomic spectrometry are sometimes rivalling and sometimes ideally cooperating techniques. The cooperating applications of the on-line coupling of IC and inductively coupled plasma–atomic emission spectroscopy or –mass spectrometry span from ultra trace analysis utilizing ion exchange as preconcentration technique via speciation applications taking advantage of the unique element specific detection offered by atomic spectroscopy until classical IC applications with atomic spectrometry as a sensitive and selective detector. Characteristics of this type of hyphenated technique are the simple physical coupling, the unique sensitivity for most elements and the superior selectivity obtainable for specific applications. 相似文献
6.
Employing both multireference configuration interaction (MRCI) and density functional theory (DFT) methods, we have studied the interaction of O? with a tetrahedral Al? cluster in the total spin triplet state. For a parallel to the base approach of O? facing an apex of the pyramid, the O? adsorption is hindered by a barrier. Both the MRCI and the DFT calculations show that after a small barrier, there are two local energy minima: a shallow one just above the apex atom and another deeper one below the apex atom. The latter corresponds to dissociative O? adsorption. We discuss the implications of these findings for the understanding of O? adsorption on defect sites of Al surfaces. 相似文献
7.
Dušan Vopálka Karel Štamberg Alois Motl Barbora Drtinová 《Journal of Radioanalytical and Nuclear Chemistry》2010,286(3):681-686
Uranyl–sulphate complexes are the predominant U(VI) species present in acid solutions resulting either from underground uranium
ore leaching or from the remediation of leaching sites. Thus, the study of U(VI) speciation in these solutions is of practical
significance. The spectra of UO2(NO3)2 + Na2SO4 solutions of different Φ
S = [SO42−]/[U(VI)] ratio at pH = 2 were recorded for this purpose. As the presence of uranyl-nitrate complexes should be expected under
these experimental conditions, the spectra of UO2(NO3)2 + NaNO3 solutions with different Φ
N = [NO3−]/[U(VI)] ratio at pH = 2 were also measured. The effects of Φ
S and Φ
N ratios value were most pronounced in wavelength interval 380–500 nm. Therefore, these parts of experimental overall spectra
were used for deconvolution into the spectra of individual species by the method proposed. It enabled to calculate stability
constants of anticipated species at zero ionic strength. The Specific Ion Interaction Theory (SIT) was used for this purpose.
Stability constants of UO2SO4, UO2(SO4)22−, UO2NO3
+ and UO2(NO3)2 coincided well with published data, but those for UO2(SO4)34− and UO2(NO3)3− were significantly lower. 相似文献
8.
9.
In this work, the interaction between dehydroindigo (an intermediary oxidized form of indigo) and Laponite clay was investigated. Dehydroindigo (DHI) has been detected when indigo is adsorbed by clay minerals, but it is relatively unstable and in the presence of water it turns back into indigo. It is, therefore, important to understand the factors that extend its stability and Laponite was chosen because the small aspect ratio implies in a large amount of silanol groups (SiOH) which would thus favor the DHI interaction through hydrogen bonding.A significant bathochromic shift (65 nm) of the DHI π®π* transition band in the visible region and changes in the relative intensities and position of the Raman bands at 1530, 1378 and 1167 cm−1 assigned to ν(NCCN), δ(CN) and ν(CN) respectively, indicate that the interaction is stronger than expected for the van der Waals and polarization forces involved in the external surfaces interactions with the siloxane groups. It was also observed that DHI presents an enhanced photochemical stability when interacting with Laponite. These results indicate that hydrogen bonding between a DHI nitrogen atom and the −SiOH or MOH groups is mainly responsible for the behavior present in the DHI + Lap system. 相似文献
10.
Bushra Naseem S.W.H. Shah Aurangzeb Hasan S. Sakhawat Shah 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2010,75(4):1341-1346
Quantitative parameters for interaction of flavonoids—the naturally occurring antioxidants, with solvents and surfactants are determined using UV–visible absorption spectroscopy. The availability of flavonoids; kaempferol, apigenin, kaempferide and rhamnetin in micelles of sodium dodecyl sulfate (SDS) is reflected in terms of partition coefficient, Kc. Thermodynamic calculations show that the process of transfer of flavonoid molecules to anionic micelles of SDS is energy efficient. A distortion in flavonoid's morphology occurs in case of kaempferol and apigenin in surfactant and water, exhibited in terms of a new band in the UV region of electronic spectra of these flavonoids. The partition coefficients of structurally related flavonoids are correlated with their antioxidant activities. 相似文献
11.
Ying Qin Yixuan Zhang Shulian Yan Ling Ye 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2010,75(5):1506-1510
The interaction between hyperoside and bovine serum albumin (BSA) was examined by fluorescence spectroscopy at 298, 304, and 310 K. The spectroscopic data were analyzed using Tachiya model and Stern–Volmer equation to determine the binding sites and apparent binding constant between hyperoside and BSA. For Tachiya model, both binding sites and apparent binding constants increased with the increasing of temperature, whereas for Stern–Volmer equation, the corresponding binding constants decreased as temperature increasing and the binding sites were independent of temperature. The positive sign of enthalpy change (ΔH) and entropy change (ΔS) suggested that hydrophobic forces played a major role in the interaction. Synchronous fluorescence spectra indicated that the conformation of protein was perturbed by the interaction of hyperoside with BSA. Moreover, the presence of metal ion affected the hyperoside-BSA binding. 相似文献
12.
The interaction of bleomycinA5 with nucleic acids has been investigated by using resonance Rayleigh scattering (RRS), molecular absorption and fluorescence spectra. The result shows that in near pH 2.2 buffer medium and absence of any metal ions, nucleic acids are capable of binding with bleomycinA5 (BLMA5) to form complexes which can remarkably enhance the RRS intensity and result in batho- chromic and hyperchromic molecular absorption of nucleic acids and fluorescence quenching of bleomycinA5. The RRS spectral characteristics for the binding products of bleomycinA5 with various DNA and RNA are similar, and the maximum RRS peaks are at 301 nm for ctDNA and sDNA, 370 nm for hsDNA, 310 nm for RNAtypeVI and RNAtypeIII, respectively. The increments of RRS intensity are greatly different in which DNA enhances greatly and RNA enhances lightly. In this work, the optimum condi- tions of the interaction and some influencing factors have been investigated. The reaction mechanism and a binding model for the interaction of BLMA5 with the nucleic acids are discussed. In addition, a highly sensitive, simple and rapid new method for the determination of DNA has been developed. The detection limits (3σ) are 5.7 ng/mL for ctDNA, 7.4 ng/mL for sDNA and 9.2 ng/mL for hsDNA, respectively. The method can be applied to determination of trace amounts of DNA. 相似文献
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14.
A. I. Lytkin V. V. Chernikov O. N. Krutova I. A. Skvortsov A. S. Korchagina 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2017,91(1):1-5
The heat effects of the interaction between a solution of α-aminobutyric acid and solutions of HNO3 and KОН are measured by means of calorimetry in different ranges of рН at 298.15 K and values of ionic strength of 0.25, 0.5, and 0.75 (KNO3). The heat effects of the stepwise dissociation of the amino acid are determined. Standard thermodynamic characteristics (Δr H 0, Δr G 0, and Δr S 0) of the reactions of acid–base interaction in aqueous solutions of α-aminobutyric acid are calculated. The connection between the thermodynamic characteristics of the dissociation of the amino acid and the structure of this compound is considered. 相似文献
15.
Thomas A. Spencer Janeta Popovici-Müller Bobbijo van Beusichem Celeste Viscardi MacMillan Carolee F. Lavey Jessica M. Sin Robert Ditchfield 《Tetrahedron》2010,66(25):4441-4451
Toward the goal of gaining further insight into carbocation-π interactions, bridged-ring aromatic alkene model systems are being investigated in which one isomer will permit π complexation of an intramolecular tertiary carbocation with a benzene ring, but the other isomer will not. The syntheses of three sets of such isomers, having, respectively, benzobicyclo[3.2.1]octene, benzobicyclo[2.2.1]heptene, and benzobicyclo[4.2.1]nonene structures, are described. 相似文献
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18.
Gunda Koellensperger Stephan Hann Günter Prinz Gerhard Stingeder Michael Bujatti-Narbeshuber 《Analytical and bioanalytical chemistry》2001,370(5):559-565
Three different analytical strategies have been evaluated for the quantification of Ir in geological samples. Glassy rock samples from Köfels and reference material WGB-1 were analyzed directly by inductively coupled plasma sector field mass spectrometry (ICP–SFMS) at mass resolution 400 using membrane desolvation and at mass resolution 9500 without membrane desolvation. Matrix separation by anion-exchange pre-concentration was also investigated. The ultrasonic nebulizer USN6000AT+ (Cetac Technologies, Omaha, NE, USA) incorporating a membrane desolvation unit was used as the sample-introduction system. Sample preparation involved complete microwave-assisted acid digestion of the silicate matrix with HNO3–HCl–HF. The results obtained by the three methods of quantification were in good agreement, showing that oxide-type interferences were effectively eliminated solely by membrane desolvation. The limits of detection were 6 pg g–1 for low resolution measurement with use of the membrane, 15 pg g–1 at a mass resolution of 9500, and 59 pg g–1 for the ion-exchange procedure. The ultimate precision obtained for the Köfelsit Ir data was, however, compromised by the small sample intake (0.3 g), because of the inhomogeneous distribution of Ir in geological samples. 相似文献
19.
The host–guest interactions between phenazine hydrochloride salt (PheH+) and hemicucurbit[n]uril (n = 6 or 12) (HemiQ[6 or 12]) have been studied by 1H NMR, UV–vis, IR, mass spectrometry (MS) and quantum chemistry. In 1H NMR spectra, the broadening of proton resonances of the hosts suggests the interactions of PheH+ with HemiQs. The quantitative stabilities of the host–guest systems have been obtained by UV–vis titration experiments, that is, the stoichiometric interactions of PheH+ with HemiQ[6] have been observed with an association constant of Ka = (2.5 ± 1.2) × 106 L mol? 1, while the 2:1 ratio complexes of PheH+ with HemiQ[12] are formed with stepwise association constants of K1 = (9.2 ± 2.8) × 104 L mol? 1 and K2 = (6.4 ± 0.9) × 105 L mol? 1, respectively, which induce a total association constant of Ka = 5.9 × 1010 L2 mol? 2. Both the 1:1 and 2:1 complexes have been detected by MS. Quantum chemistry calculations have been used to understand the static structures and thermodynamic stabilities of the supramolecular assemblies. 相似文献
20.
Indranil Chakraborty Tanushree Chakraborty Satya P. Moulik 《Colloid and polymer science》2013,291(8):1939-1948
The present study entails interaction between the cationic polymer N,N-dimethylhydroxyethyl cellulose (JR 400) and the double-tailed anionic surfactant Na-bis-2-ethyhexylsulphosuccinate (NaAOT). This oppositely charged polymer and surfactant are expected to cause coacervation and precipitation; hence, we have observed formation of thick solution similar to diluted gel at [JR 400]?~?0.01 and 0.10 %?w/v in aqueous solution. Viscometry, conductometry, tensiometry, and microcalorimetry techniques are used to monitor the interaction process. The results are explained in the light of both intrachain and interchain linking by way of NaAOT reverse micelle formation. Adsorption of NaAOT monomers onto the charged side chains of the polymer shields interchain electrostatic repulsion, leading to the formation of hydrophobic microdomains and microscopic heterogeneity in the solution. The morphologies of the domains depend on the level of addition of NaAOT in the system. The different stages of physiochemical changes that arise in solution have been identified by the use of different techniques, and correlations of the results have been attempted in terms of pragmatic models. 相似文献