共查询到20条相似文献,搜索用时 31 毫秒
1.
Kannappan Santhakumar Narayanasamy Kumaraguru Sankarlingam Arunachalam Mahadevimanglam Narayanasamy Arumugham 《Transition Metal Chemistry》2006,31(4):475-481
The kinetics and mechanism of iron(II) reduction of cis- α-chloro/bromo(cetylamine)(triethylenetetramine) cobalt(III) surfactant complex ions were studied spectrophotometrically
in an aqueous acid medium by following the disappearance of CoIII using an excess of the reductant under pseudo-first-order conditions: [FeII = 0.25 mol dm−3, [H+ = 0.1 mol dm−3, [μ = 1.0 mol dm−3 ionic strength in a nitrogen atmosphere at 303, 308 and 313 K. The reaction was found to be second order and showed acid
independence in the range [H+ = 0.05−0.25 mol dm−3. The second order rate constant increased with CoIII concentration and the presence of aggregation of the complex itself altered the reaction rate. The effects of [FeII], [H+] and [ μ] on the rate were determined. Activation and thermodynamic parameters were computed. It is suggested that the reaction of
Fe2+(aq) with CoIII complex proceeds by an inner-sphere mechanism. 相似文献
2.
A novel chemiluminescence (CL) detection scheme for the simultaneous determination of vitamin B1 and vitamin B2 has been developed.
After being separated by capillary electrophoresis (CE), the analytes were determined by direct CL of vitamin B1 and vitamin
B2-potassium hexacyanoferrate(III) (K3[Fe(CN)6]) in alkaline aqueous solution. Parameters affecting CE-CL separation and detection, such as the pH value and the concentration
of electrolyte and K3[Fe(CN)6] were optimized. Vitamin B1 and vitamin B2 are completely resolved with migration times shorter than 5 min. Under the optimal
conditions, a linear range from 0.04 to 50, 0.08 to 90 μg mL−1 and a detection limit of 0.01, 0.03 μg mL−1 (signal-to-noise ratio = 3) for vitamin B1 and vitamin B2 respectively, were achieved. The relative standard deviations (R.S.D.)
for 0.5 μg mL−1 of vitamin B1 and 0.8 μg mL−1 of vitamin B2 (n = 11) were 2.9 and 3.7%, respectively. The applicability of the method was examined for the analysis of pharmaceutical tablets.
Correspondence: Juan Bai, Physical Education and Human Kinesiology Department, University of Science and Technology of Qingdao,
Qingdao 266042, China 相似文献
3.
M. N. Sokolov E. V. Chubarova E. V. Peresypkina A. V. Virovets V. P. Fedin 《Russian Chemical Bulletin》2007,56(2):220-224
The reactions of the tetranuclear hydroxo complexes [M4(μ2-OH)8(H2O)16]8+ (M = Zr or Hf) with the lacunary Keggin-type ([α-PW11O39]7−) and Dawson-type ([α 2-P2W17O61]10−) phosphotungstates in aqueous solutions produce the sandwich polyoxometalate complexes [M(α-PW11O39)2]10− (M = Zr (1) or Hf (2)) and [M(α 2-P2W17O61)2]16− (M = Zr (3) and Hf (4)). The complexes were isolated and structurally characterized as salts with potassium and dimethylammonium cations. The zirconium
and hafnium atoms have a square antiprismatic coordination environment (coordination number is 8). In all complexes, the mutual
arrangement of the ligands corresponds to the syn isomer. Hafnium complexes 2 and 4 are the first structurally characterized polyoxometalate complexes of this metal. The structures of the resulting compounds
were confirmed also by 31P NMR spectroscopy in solution.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 214–218, February, 2007. 相似文献
4.
T. Basinska S. Slomkowski A. Dworak I. Panchev M. M. Chehimi 《Colloid and polymer science》2001,279(9):916-924
Polystyrene microspheres with polyglycidol (polyGL) in a surface layer were synthesized in batch radical emulsifier-free
emulsion copolymerizations of styrene and surfmers, α-t-butoxy-ω-vinylbenzyl-polyGL macromonomers (VB-polyGL). Macromonomers
with number-average molecular weight Mˉ
n=950 (VB-polyGL950) and Mˉ
n=2700 (VB-polyGL2700) were used for these polymerizations. In all syntheses the initial concentrations of styrene and initiator
(K2S2O8) were constant. The initial macromonomer-to-styrene ratios were varied from 1.10 × 10−3 to 1.64 × 10−2 mol/mol and from 3.46 × 10−4 to 3.47 × 10−3 mol/mol for VB-polyGL950 and VB-polyGL2700, respectively. The diameters of microspheres obtained were smaller for the syntheses
with higher concentrations of macromonomers. Syntheses with VB-polyGL950 yielded microspheres with number-average diameters
(Dˉ
n) from 216 to 900 nm and with a bimodal diameter distribution. The number-average diameters of microspheres obtained with
VB-polyGL2700 varied from 220 to 650 nm, depending on the initial concentration of macromonomer. Their diameter distributions
were monomodal, with a diameter polydispersity parameter (ratio of weight-average and number-average diameters) in the range
1.007≤Dˉ
w/Dˉ
n≤1.022. For each type of microsphere the fraction of polyGL in a surface layer and the surface concentration of sulfate anions
were determined. The fraction of polyGL in the surface layer was related to the initial monomer composition in the polymerizing
mixture. Adsorption of human serum albumin onto surfaces of some poly(styrene/VB-polyGL) microspheres was up to 10 times lower
than for the polystyrene microspheres obtained in a similar emulsifier-free emulsion polymerization of styrene.
Received: 26 September 2000/Accepted: 19 February 2001 相似文献
5.
J. Wang X. Zh. Liu X. F. Wang G. R. Gao Zh. Q. Xing X. D. Zhang R. Xu 《Journal of Structural Chemistry》2008,49(1):75-83
The two title coordination compounds, (NH4)3[TbIII(ttha)]·5H2O (ttha = triethylenetetramine-N,N,N′,N″,N‴,N‴-hexaacetic acid) and (NH4)4[Tb
2
III
(ttha)]·9H2O (dtpa = diethylenetriamine-N,N,N′,N″,N″-pentaacetic acid), have been prepared and characterized by FT-IR, elemental analyses,
TG-DTA and single crystal X-ray diffraction techniques. The (NH4)3[TbIII(ttha)]·5H2O compound is monoclinic, P21/c; a = 10.398(1) Å, b = 12.791(1) Å, c = 23.199(2) Å; β = 90.914(2)°; V = 3084.9(5) Å3; Z = 4; D
calc = 1.704 g/cm3; μ(MoK
α
) = 2.376 mm™; R = 0.023 and wR
2 = 0.049 for 5429 observed reflections with I ≥ 2σ(I). The [TbIII(ttha)]3− complex anion in the crystal has a nine-coordinate mononuclear molecular structure with pseudo-monocapped square-antiprismatic
configuration. The (NH4)4[Tb
2
III
(dtpa)2]·9H2O compound is triclinic, P-1; a = 9.739(1) Å, b = 10.010(1) Å, c = 12.968(2) Å; α= 85.890(2)°, β = 77.338(2)°, γ = 77.587(2)°; V = 1204.2(2) Å3; Z = 1; D
calc = 1.832 g/cm3; μ(MoK
α
) = 3.015 mm™; R = 0.024 and wR
2 = 0.060 for 4750 observed reflections with I ≥ 2σ(I). The [Tb
2
III
(dtpa)2]4− complex anion has a binuclear structure in the crystal; the two TbIII centers are equivalent and have a nine-coordinate environment with the same pseudo-tricapped trigonal-prismatic configuration.
The thermal analysis revealed that the coordination cores of the (NH4)3[TbIII(ttha)]·5H2O and (NH4)4[Tb
2
III
(dtpa)2]·9H2O compounds are stable up to 221°C and 252°C, respectively.
Original Russian Text Copyright ? 2008 by J. Wang, X. Zh. Liu, X. F. Wang, G. R. Gao, Zh. Q. Xing, X. D. Zhang, and R. Xu
The text was submitted by the authors in English. Zhurnal Strukturnoi Khimii, Vol. 49, No. 1, pp. 81–89, January–February, 2008. 相似文献
6.
J. Wang Y. Wang Zh. H. Zhang X. D. Zhang J. Tong X. Zh. Liu X. Y. Liu Y. Zhang Zh. J. Pan 《Journal of Structural Chemistry》2005,46(5):895-905
Syntheses and structure determination of the YIII complexes with ethylenediaminetetraacetic acid (H4edta) and trans-1,2-cyclohexanediaminetetraacetic acid (H4cydta) are reported. The crystal and molecular structures of the complexes, as well as their molecular formulas and compositions,
were determined by single-crystal X-ray structure analyses, NMR, IR, thermogravimetric measurements, and elementary analyses.
The crystal of the Na[YIII(edta)(H2O)3]·5H2O complex belongs to the orthorhombic crystal system and space group Fdd2. The crystal data are as follows: a = 19.355(5) Å, b = 35.431(11) Å, c = 12.122(3) Å, V = 8313(4) Å3, Z = 16, M = 544.23, Dc = 1.739 g·cm−3, μ = 2.908 mm−1 and F(000) = 4480. The final R and Rw are 0.0483 and 0.1172 for 3284 (I > 2σ(I)) unique reflections, R and Rw are 0.0678 and 0.1440 for all 8499 reflections, respectively. The YIIIN2O7 part in the [YIII(edta)(H2O)3]− complex anion has a pseudo-monocapped square antiprismatic nine-coordinate structure, in which the six coordinated atoms
(two N and four O) from the edta ligand and three water molecules are coordinated to the central YIII ion directly. The crystal of the Na[YIII(cydta)(H2O)2]·5H2O complex belongs to the triclinic crystal system and
space group. The crystal data are as follows: a = 8.405(2) Å, b = 9.970(2) Å, c = 14.763(4) Å, α = 88.538(4)°, β = 76.193(4)°, γ = 88.100(4)°, V = 1200.6(5) Å 3, Z = 2, M = 580.31, Dc = 1.605 g·cm−3, μ = 2.519 mm−1 and F(000) = 600. The final R and Rw are 0.0381 and 0.0911 for 4198 (I > 2σ(I)) unique reflections, R and Rw are 0.0530 and 0.1041 for all 6186 reflections, respectively. The YIIIN2O6 part in the [YIII(cydta)(H2O)2]− complex anion has a pseudo square antiprismatic eight-coordinate structure in which the six coordinated atoms (two N and
four O) from the cydta ligand and two water molecules are coordinated to the central YIII ion directly.
Original Russian Text Copyright ? 2005 by J. Wang, Y. Wang, Zh. H. Zhang, X. D. Zhang, J. Tong, X. Zh. Liu, X. Y. Liu, Y.
Zhang, and Zh. J. Pan
__________
Translated from Zhurnal Strukturnoi Khimii, Vol. 46, No. 5, pp. 928–938, September–October, 2005. 相似文献
7.
The reaction of [S2Mo(μ-S)2Fe(SPh)2]2− with [Fe(SPh)4]2− produces the dicuboidal cluster [{MoFe3S4(SPh)3}2(μ-(SPh)3]3− in a three stage process studied by 1H-n.m.r. spectroscopy and stopped-flow spectrophotometry. The initial stage involves the formation of the linear trinuclear
[(PhS)2Fe(μ-S)2Mo(μ-S)2Fe(SPh)2]2− and the kinetics indicate an equilibrium reaction (k1Mo
= 2.5±0.3x 102 dm3 mol−1 s−1, k−1Mo = 0.8±0.1 s−1). The second stage involves the reduction of [(PhS)2Fe(μ-S)2Mo(μ-S)2Fe(SPh)2]2− by [Fe(SPh)4]2− to form [(PhS)2Fe(μ-S)2Mo(μ-S)2Fe(SPh)2]3− which subsequently rearranges to form the voided cuboidal [MoFe2S4(SPh)3]2−. The kinetics of the second stage exhibits a simple first order dependence on the concentrations of both [(PhS)2Fe(μ-S)2Mo(μ-S)2Fe(SPh)2]3− and [Fe(SPh)4]2− (k2Mo
= 25 ± 2 dm3 mol−1 s−1). The Kinetics of the third stage have not been studied but must involve incorporation of the final Fe and formation of the
dicuboidal [{MoFe3S4(SPh)3}2(μ-SPh)3]3−. The kinetics of the reaction between [(EtS)2Fe(μ-S)2V(μ-S)2Fe(SEt)2]3− and [Fe(SEt)4]2− to form [{VFe3S4(SEt)3}2(μ-SEt)3]3− have also been studied. An important difference between this reaction and the formation of the analogous [{MoFe3S4(SPh)3}2(μ-SPh)3]3− is that the formation of [{MoFe3S4(SPh)3}2(μ-SPh)3]3− from [(PhS)2Fe(μ-S)2Mo(μ-S)2Fe(SPh)2]2− involves a change in the redox state of the cluster, whilst the formation of [{VFe3S4(SEt)3}2(μ-SEt)3]3− from [(EtS)2Fe(μ-S)2V(μ-S)2Fe(SEt)2]3− requires no change in redox state. The reaction between [(EtS)2Fe(μ-S)2V(μ-S)2Fe(SEt)2]3− and [Fe(SEt)4]2− involves two stages. The kinetics of the faster phase is associated with a rate law analogous to that observed for the reaction
between [(PhS)2Fe(μ-S)2Mo(μ-S)2 Fe(SPh)2]2− with [Fe(SPh)4]2−: a first order dependence on the concentrations of [(EtS)2Fe(μ-S)2V(μ-S)2Fe(SEt)2]3− and [Fe(SEt)4]2− (k2V = 1.1±0.1 x 103 dm3 mol−1 s−1. This observation indicates that whilst there is no change in redox state between [(EtS)2Fe(μ-S)2V(μ-S)2Fe(SEt)2]3− and [{VFe3S4(SEt)3}2(μ-SEt)3]3−, reduction is necessary to catalyse the conversion of the linear [(EtS)2Fe(μ-S)2V(μ-S)2Fe(SEt)2]3− into the voided cuboidal [VFe2S4(SEt)3]3−. The results of the studies reported in this paper together with those on other putative reactions involved in the assembly
of cuboidal clusters, have been combined to present a scheme of the mechanism of cuboidal cluster assembly.
Electronic supplementary material Electronic supplementary material is available for this article at
and accessible for authorised users. 相似文献
8.
Qing-Lun Wang Xue-Qiao Jia Dai-Zheng Liao Shi-Ping Yan Peng Cheng Guang-Ming Yang Hong-Xia Ren Zong-Hui Jiang 《Transition Metal Chemistry》2006,31(4):434-440
A binuclear copper(II) complex with two symmetric end-on azido bridges: [Cu2(tacn)2(μ-N3)2](ClO4)2 · CH3OH (1), where tacn = 1,4,7-triazacyclononane, has been synthesized and structurally as well as magnetically characterized. Compound
(1) has the discrete binuclear structure, bridged by two end-on N3− anions. The macrocyclic ligand tacn functions as a terminal ligand. The magnetic data of compound (1) were analyzed by means of Ĥ = −2JŜ1Ŝ2 − DŜz, leading to J = 2.49 cm−1, g = 2.08, D = ±0.97 cm−1, zJ′ = −0.47 cm−1. The ferromagnetic interaction is discussed on the basis of the structural features and is compared with the model structure
of Ruiz. 相似文献
9.
Mahmure Ü. Özgür Güzin Alpdoğan Bürge Aşçi 《Monatshefte für Chemie / Chemical Monthly》2002,133(2):219-223
Summary. A simple and rapid derivative spectrophotometric assay procedure is described for the analysis of caffeine (1), acetaminophen (2), and propyphenazone (3) in tablet formulations. The concentration range of application is 5.0–25.0 μg·cm−3 for 2 and 3 and 1.0–5.0 μg·cm−3 for 1. The method involves the extraction of the drugs from tablets with 0.1 N H2SO4, filtration, appropriate dilution, and measurement of the fourth derivative absorbance values at zero crossing wavelengths
of 230.0, 263.2, and 256.6 nm for 1, 2, and 3. As a reference method, a reversed phase HPLC procedure was developed. Commercially available tablets were analyzed; statistical
comparison of the results with those obtained from the reference method showed good agreement. The derivative spectrophotometric
method has the advantage of being simple, rapid, inexpensive, and easy to perform.
Received April 18, 2001. Accepted (revised) June 5, 2001 相似文献
10.
Y. H. Xing Z. Sun W. Zou J. Song K. Aoki M. F. Ge 《Journal of Structural Chemistry》2006,47(5):913-922
The reaction of VO(acac)2 (acac = acetylacetonate) with NaHB(pz)3 (pz = pyrazole) or NaHB(3,5-Me2pz)3 in methanol gave vanadium(IV) complexes HB(pz)3VO(acac) (1) or HB(3,5-Me2pz)3VO(acac)·CH3CN (2), respectively. The complexes 1 and 2 were characterized by elemental analysis, IR, UV-vis, NMR and X-ray diffraction crystallography methods. Complex 1 crystallizes in space group P21/c, a = 7.641(2) Å, b = 17.008(4) Å, c = 13.362(2) Å; β = 92.092(17)°, V = 1735.5(7) Å3, Z = 4. Complex 2 crystallizes in space group P21/c, a = 17.410(13) Å, b = 8.076(16) Å, c = 19.300(13) Å; β = 101.75(5)°, V = 2657(6) Å3, Z = 4. X-ray structure analyses have shown that the complexes 1 and 2 are monomeric with a similar coordination environment of the vanadium atom. Luminescence properties and cytotoxic effects
of the complexes are discussed. On CBRH-7919 cells, the complexes 1 and 2 caused a slight stimulation of growth at low doses (1–10 μM) and a significant cytotoxic effect at higher doses (100–1000
μM). The electronic structure and the bonding characters of the two complexes were analyzed with ab initio calculations.
Original Russian Text Copyright ? 2006 by Y. H. Xing, Z. Sun, W. Zou, J. Song, K. Aoki, and M. F. Ge
__________
Translated from Zhurnal Strukturnoi Khimii, Vol. 47, No. 5, pp. 924–932, September–October, 2006. 相似文献
11.
Pawel Pohl Israel Jimenéz Zapata Edgar Voges Nicolas H. Bings José A. C. Broekaert 《Mikrochimica acta》2008,161(1-2):175-184
A 2.45 GHz low power microwave microstrip plasma (MSP) exiting the wafer and operated with Ar at atmospheric pressure was
used for the optical emission spectrometric determination of Hg with the aid of a miniaturized optical fiber spectrometer
with a CCD detector and the cold vapor (CV) generation technique using NaBH4 and SnCl2 as reductants. The experimental conditions were optimized with respect to the relative intensity of the Hg I 253.6 nm line
and its signal-to-background intensity ratio (SBR). So as to understand the results of the optimization experiments, the excitation
temperatures as measured from Ar I lines (T
exc) and the electron number densities (n
e) for the Ar MSP loaded with Hg vapors were determined and found to be in the range from 5500 to 6300 K and from 1.4 to 2.0
× 1014 cm−3, respectively. Under the optimized conditions, the detection limit for Hg of the CV-MSP-OES using SnCl2 as the reducing agent was found to be much lower (0.11 ng mL−1) than in the case where NaBH4 was used (9 ng mL−1). The linearity range was found to be up to 1 μg mL−1 while the precision was of the order of 0.7–5%. The procedure with SnCl2 as reductant was used for the determination of Hg at a concentration of 0.2 μg mL−1 in synthetic water samples containing 1 to 4% (m/v) of NaCl with an accuracy of 3% as well as in a solution of the domestic
sludge standard reference material (NIST SRM 2781) with a certified concentration for Hg of 3.64 ± 0.25 μg g−1 for which 3.55 ± 0.41 μg g−1 was found.
Correspondence: J. A. C. Broekaert, Institut für Anorganische und Angewandte Chemie, Universit?t Hamburg, 20146 Hamburg, Germany 相似文献
12.
The chemiluminescence (CL) system K2MnO4-luminol is shown to be useful for the determination of lead(II). The method is based on the catalytic effect of Pb(II) on
the CL reaction. The linear range was 3 × 10−3–9 × 10−1 mg L−1 (r = 0.9971) and the relative standard deviation (R.S.D.) for 5 × 10−2 mg L−1 Pb(II) measurement was 0.7% (n = 11). The detection limit was 3 × 10−4 mg L−1 (3σ) Pb(II). Based on this, an in vivo, on-line, real-time analytical system for monitoring the metabolism of free lead(II)
in rabbit blood was developed. A microdialysis probe, implanted in the vein of a rabbit, was perfused with perfusate at a
flow rate of 5 μL min−1. The concentration of free lead(II) in the dialysate was determined on-line with a flow-injection CL system. This system
included microdialysis sampling, on-line separation and chemiluminescence detection. The concentration-time curve of lead(II)
was in accordance with the one-compartmental open model, T1/2 (elimination half-life), Tmax (peak time) and Cmax (peak concentration) were 37.77 min, 85.20 min and 0.137 mg L−1, respectively. 相似文献
13.
Klaus-Michael Ochsenkühn Theopisti Lyberopoulou G. Koumarianou Maria Ochsenkühn-Petropoulou 《Mikrochimica acta》2008,160(4):485-492
In the time period from June 2005 to May 2006 in 42 sampling campaigns 84 filter samples of airborne particulate matter, coarse
(PM10–2.5) and fine (PM2.5), were collected using a Gent stacked filter unit in the coastal industrial area of Aspropyrgos in Attica, Greece. The average
PM10 (PM10–2.5 + PM2.5) concentration was found to be 66 μg · m−3, exceeding more than 1.6 times the annual limit of 40 μg · m−3. The samples were analysed for Cl−, NO3
−, SO4
2−, Ca2+, Mg2+, Na+, K+ and NH4
+ using ion chromatography. The data were compared with results obtained with other spectrometric methods, such as inductively
coupled plasma-atomic emission spectrometry, atomic absorption spectrometry, energy dispersive X-ray fluorescence and reflectometry.
The determined average ionic content comprised about 44% of the PM10 mass. The ionic composition, as well as the possible matrix compounds in both fractions were evaluated by dividing the sampling
period into summer and winter season. In the PM10–2.5/PM2.5 fraction in summer time the concentrations of Ca2+, Mg2+ and NO3
− were enriched in the coarse fraction. In winter time all species were enriched in the coarse fraction, especially Ca2+, Cl− and NO3
−. NH4
+ was constantly higher in the fine fraction in summer as well as in winter time. Factor analysis was applied to obtain correlations
between cations and anions leading to matrix compounds in both fractions. From the evaluation of the results obtained, some
of the local air pollution sources could be identified.
Correspondence: Klaus-Michael Ochsenkühn, Laboratory for Trace Element Studies, Institute of Physical Chemistry, NCSR “Demokritos”,
Aghia Paraskevi 15310, Athens, Greece 相似文献
14.
Ashraf A. Mohamed Saleh A. Ahmed Mohamed F. El-Shahat 《Monatshefte für Chemie / Chemical Monthly》2002,133(1):31-40
Summary. A highly selective, sensitive, and simple catalytic method for the determination of molybdenum in natural and waste waters
was developed. It is based on the catalytic effect of Mo(VI) on the oxidation of 2-aminophenol with H2O2. The reaction is monitored spectrophotometrically by tracing the oxidation product at 430 nm after 10 min of mixing the reagents.
Addition of 800 μg · cm−3
EDTA conferred high selectivity; however, interfering effects of Au(III), Cr(III), Cr(VI), and Fe(III) had to be eliminated by
a reduction and co-precipitation procedure with SnCl2 and Al(OH)3. Mo(VI) shows a linear calibration graph up to 11.0 ng · cm−3; the detection limit, based on the 3S
b-criterion, is 0.10 ng · cm−3. The unique selectivity and sensitivity of the new method allowed its direct application to the determination of Mo(VI) in
natural and waste waters.
Received April 11, 2001. Accepted (revised) June 18, 2001 相似文献
15.
Jia-Ming Liu Liang-Yun Xu Shi-Rong Hu Lan Wei Tian-Long Yang Guo-Hui Zhu Xiao-Mei Huang Zhi-Ming Li Xiao-Hua Chen 《Mikrochimica acta》2008,161(1-2):217-224
In the presence of the heavy atom perturber Pb(Ac)2, fluorescein (HFin) can emit strong and stable room temperature phosphorescence (RTP) on the surface of a nitrocellulose
membrane (NCM) at λex
max/λem
max = 480/648 nm. It can be spiked with the 1.5-generation polyamidoamine dendrimers (abbreviated: D-1.5) to emit stronger RTP.
It was found that a quantitative specific affinity adsorption (AA) reaction between concanavalin agglutinin (abbreviated:
Con A) labeled with D-1.5-HFin and N-acetylglucosamine (G) could be carried out on the surface of NCM. The product of the
reaction (D-1.5-HFin- Con A-G) could emit strong and stable RTP, and the ΔIp was proportional to the content of G. According to the above facts, a new method for determination of G by affinity adsorption
solid substrate-room temperature phosphorimetry (AA-SS-RTP) was established, based on Con A labeled with fluorescein using
D-1.5 dendrimers molecules as sensitizer. The linear range of the sandwich method was 0.040–60 pg G spot−1 (corresponding concentration range: 0.10–150 ng mL−1; sample volume: 0.40 μL spot−1). The regression equation of the working curve was ΔIp = 6.880 + 5.610 mG pg spot−1, r = 0.9987. The working solutions containing 0.10 and 150 ng mL−1 G were determined repeatedly 11 times, respectively. The corresponding RSDs were 2.9 and 3.8%. The detection limit of this
method calculated by 3Sb/k was 0.021 pg spot−1 (5.2 × 10−11 g mL−1). Compared with the direct method (detection limit: 0.078 pg spot−1, linear range: 0.40–40 pg G spot−1), the sensitivity was obviously improved and the linear range was wider. This method has been successfully applied to the
determination of G in human plasma, as well as to the supervision and forecast of human diseases, for it is of good sensitivity,
accuracy and precision.
Correspondence: Jia-Ming Liu, Department of Chemistry and Environmental Science, Zhangzhou Normal College, Zhangzhou 363000,
P.R. China 相似文献
16.
X. Ai H. Hutter M. Gritsch H. Börner J. D. Sunderkötter H. Bubert H. Jenett 《Analytical and bioanalytical chemistry》2000,366(1):41-47
A strong Al+ and a minor Ti+ peak without a proportional increase of the O+ signal in SNMS high-frequency sputtering mode (HFM) time profiles of an insulating μm-thick oxide layer on Ti-48Al-2Cr-2Nb
led us to check for a possible contribution of positive secondary ions (SI+). SI+ and SI– (negative secondary ions) can be detected in ion energy spectra. This is shown using Al+, O–, AlO–, and AlO2
– ions sputtered from massive Al2O3. Similarly, and depending on stoichiometry, also Ti+ from mixed sintered, microscopically inhomogeneous Al2O3-TiO2-SiO2 pellets has been identified to be partly SI+. The subtraction of an assumed contribution of ionized secondary neutrals (SN+) suggests that SI+ may form several 10% of the detected ions obtained in the HFM sputtering and plasma processes. However, the positive surface
potential of some 10 V being necessary to cause detectable SI+ contributions does not build up on μm-thin insulating layers. Therefore, we have to conclude that the Al+ and Ti+ peaks in the sputter time profiles of the μm-thick oxide layer on Ti-48Al-2Cr-2Nb which are accompanied by an O+ deficiency cannot have been caused by SI+. Instead, their more probable origin is the inhomogeneous Al2O3 interlayer itself. Together with the residues of a topmost TiO2 layer which has strongly been depleted in O by preferential sputtering, the relative O+ deficiency may be explained without assuming SI+ contributions.
Received: 22 February 1999 / Revised: 1 July 1999 / Accepted: 6 July 1999 相似文献
17.
A film of single-wall carbon nanotubes (SWNTs) and didodecyldimethylammonium bromide (DDAB) is prepared by casting a solution
of SWNTs and DDAB onto the surface of a gold electrode. The electrochemical behavior of the film is investigated by electrochemical
impedance spectroscopy and cyclic voltammetry. In a 0.10 M phosphate buffer solution of pH 7.0, the film-modified electrode
gives a pair of redox peaks in cyclic voltamograms, with the anodic and cathodic peak potentials of 0.095 and 0.042 V. The
peak currents change linearly with the scan rate at 30–500 mV/s. The modified electrode has an excellent electrocatalytic
activity towards the oxidation of ascorbic acid (AA). The catalysis currents are proportional to the AA concentration in the
range of 5.0 × 10−4 to 3.2 × 10−2 M. The linear-regression equation is i (μA) = 1.2079 + 1.3987 × 103
c
AA (M), with a correlation coefficient of 0.9995. The detection limit is 2.2 × 10−4 M (signal-to-noise ratio of 3). The Michaelis-Menten constant (K
m) is 1.0 × 10−4 M by the Lineweaver-Burk equation.
__________
From Elektrokhimiya, Vol. 41, No. 10, 2005, pp. 1193–1199.
Original English Text Copyright ? 2005 by Cheng, Jin, Zhang.
The text was submitted by the authors in English. 相似文献
18.
In pH 3.5 Britton—Robinson buffer solution double-stranded (ds) DNA can react with malachite green (MG) to form an interaction
complex, which resulted in the decrease of the electrochemical response of MG, MG had a well-defined second-order derivative
linear sweep voltammetric peak at −0.73 V (vs. SCE). After the addition of dsDNA into MG solution, the reductive peak current decreased with the positive shift of peak
potential, which was the typical characteristic of intercalation. Based on the interaction, an indirect electrochemical determination
method for dsDNA was established. The optimum conditions for the reaction were investigated and there were little or no interferences
from the commonly coexisting substances. The decrease of peak current was linear with the concentration of dsDNA over the
range of 0.8–12.0 μg cm−3 with the linear regression equation as ΔI
p″/nA = 91.70 C/(μg cm−3) + 74.55 (n = 10, γ = 0.990). The detection limit was calculated as 0.46 μg cm−3 (3σ). The method had high sensitivity and was further applied to the dsDNA synthetic samples with satisfactory result. The interaction
mechanism was discussed with the intercalation of DNA-MG to form a supramolecular complex and the stoichiometry of the supramolecular
complex was calculated by electrochemical method with the binding number 3 and the binding constant 2.35 × 1015 (mol dm−3)−3. 相似文献
19.
The crystal structure of bis(semicarbazido)copper(II) nitrate [Cu(NH2NHC(O)NH2)2](NO3)2 has been studied by X-ray diffraction. Monoclinic crystals, a = 6.835(2) Å, b = 7.733(2) Å, c = 10.320(3) Å, β = 105.701(3)°, V = 525.1(2) Å3, space group P21/c, Z = 2, d
msd = 2.136 g/cm3, μ(MoK
α) = 2.143 mm−1. The structure was solved with the program for automatic analysis of Patterson’s function and refined by full-matrix least
squares in an anisotropic approximation for all non-hydrogen atoms using 753 independent reflections; R
1 = 0.0203. The square environment of the Cu atom is formed from the amino nitrogen atoms of the hydrazine fragments and the
C=O oxygen atoms of the two semicarbazide bidentate molecules (Cu-N 1.928 Å, Cu-O 1.999 Å). The axial positions are occupied
by the O atoms of the NO
3
−
outer-spheric anions (Cu-O 2.505 Å). In the structure, the complex cations and the NO
3
−
anions are linked into a framework by N-H...O type hydrogen bonds.
Original Russian Text Copyright ? 2007 by G. V. Romanenko, Z. A. Savelieva, and S. V. Larionov
__________
Translated from Zhurnal Strukturnoi Khimii, Vol. 48, No. 2, pp. 370–373, March–April, 2007. 相似文献
20.
Determination of Veterinary Pharmaceuticals in Production Wastewater by HPTLC-Videodensitometry 总被引:1,自引:0,他引:1
S. Babić D. Mutavdžić D. Ašperger A. J. M. Horvat M. Kaštelan-Macan 《Chromatographia》2007,65(1-2):105-110
An SPE-HPTLC method for simultaneous identification and quantification of seven pharmaceuticals in production wastewater was
optimized and validated. The studied compounds were enrofloxacine, oxytetracycline, trimethoprim, sulfamethazine, sulfadiazine,
sulfaguanidine and penicillin G/procaine. The method involves solid-phase extraction on hydrophilic-lipophilic balance cartridges
with methanol and HPTLC analysis of extracts on CN modified chromatographic plates followed by videodensitometry at 254 and
366 nm. Optimization of chromatographic separation was performed by systematic variation of the mobile phase composition using
genetic algorithm approach and the optimum mobile phase composition for TLC separation was 0.05 M H2C2O4:methanol = 0.81:0.19 (v/v). Linearity of the method was demonstrated in the ranges from 1.5 to 15.0 μg L−1 for enrofloxacine, 100–500 μg L−1 for oxytetracycline, 150–600 μg L−1 for trimethoprim, 300–1100 μg L−1 for sulfaguanidine and 100–400 μg L−1 for sulfamethazine, sulfadiazine and penicillin G/procaine with coefficients of determination higher than 0.991. Mean recoveries
ranged from 74.6 to 117.1% and 55.1 to 108.0% for wellspring water and production wastewater, respectively. Only sulfaguanidine
showed lower results. The described method has been applied to the determination of pharmaceuticals in wastewater samples
from pharmaceutical industry. 相似文献