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1.
An optode system based on a plasticized polymer membrane containing cesium ion-selective fluoroionophore and lipophilic anions
for the determination of cesium ions has been developed. In this work, 15-crown-5 derivative including anthracene was used
as a fluoroionophore. Emission intensity of the optode membrane incorporating 15-crown-5-anthracene was measured at 500 nm
with excitation at 360 nm in the presence of Tris-HCl buffer solution. Under optimum experimental condition, the relative
fluorescence intensity was linear with the concentration of cesium ion in the range of 1.0 × 10-4 M to 1.0 × 10-1 M and the detection limit was obtained 4.2 × 10-5 M, as defined by LOD = 3 × Sb/m (where Sb=standard deviation of blank signal and, m=slope of the calibration curve). The effect of pH of sample solution on the fluorescent
response, the selectivity, response time and reproducibility of the optode membrane were also discussed. The fluorescent optode
system shows a high selectivity and sensitivity for cesium ion with respect to other cations such as K+, Na+ and Li+. 相似文献
2.
Study on the New Fluorescence Enhancement System of Tb –N-(2 - Pyridinyl) Ketoacetamide-Et<Subscript>3</Subscript>N-Zn and its Application 总被引:1,自引:0,他引:1
A sensitive fluorescence enhancement system was developed for the determination of zinc (II). The fluorescence intensity of
the Tb- N- (2 - Pyridinyl) ketoacetamide (PKA) system was greatly enhanced by the addition of triethylamine (Et3N) and zinc nitrate in the methanol solution. The excitation and emission wavelengths were 329 nm and 546 nm, respectively.
Under optimal conditions, the fluorescence intensities varied linearly with the concentration of Zn2+ in the range of 8.0×10−7−5.0×10−6 M with a detection limit of 9.9×10−8 M. The interferences of some substances were described. This method was applied to the determination of amounts of Zn2+ in soybean, rice, and wheat, respectively. The results showed that the proposed procedure is a high selective, simple, and
rapid method to the determination of Zn2+ ion. The mechanism of fluorescence enhancement was also studied. 相似文献
3.
A fluorescence enhancement phenomenon in the europium (Eu)–Ofloxacin (OF)–Sodium Dodecyl Benzene Sulfonate (SDBS) fluorescence
system was observed when Gd3+ was added. The fluorescence intensity of the systems was measured (λ
ex/λ
em = 280/612 nm) at pH 7.8. Under optimum conditions, a linear relationship between the enhanced fluorescence intensity and
the Eu3+ concentration in the range of 5.0 × 10−10 ∼ 2.0 × 10−7 mol·L−1 was observed. The detection limit of Eu3+ was 1.46 × 10−10 mol·L−1 (S/N = 3). This method was used for the determination of trace amounts of europium in synthetic rare earth samples with satisfactory
results. In addition, the interaction mechanism is also studied. 相似文献
4.
A new, simple and accurate spectrofluorimetric method for the determination of metoclopramide hydrochloride was developed.
The metoclopramide hydrochloride can remarkably enhance the luminescence intensity of the Tb3+ ion doped in PMMA matrix at λex = 360 nm in methanol at pH 6.9. The intensity of the emission band at 545 nm of Tb3+ ion doped in PMMA matrix is increased due to the energy transfer from metoclopramide hydrochloride to Tb3+ in the excited stated. The effect of different parameters, e.g., pH, temperature, Tb3+ concentration, foreign ions that control the fluorescence intensity of the produced ion associate was critically investigated.
The calibration curve of the emission intensity at 545 nm shows linear response of metoclopramide over a concentration range
of 5 × 10−5–5.0 × 10−8 M with detection limit of 8.7 × 10−10 M. The method was used successfully for the determination of metoclopramide in pharmaceutical preparations and human serum.
The average recovery of 99.48% with standard deviation of 0.32% and 96.98% with standard deviation of 0.4%, of pharmaceutical
preparations and human serum respectively, were obtained which compared will with the results obtained from standard LC method
of average recovery 99.04% and standard deviation of 0.6% and average recovery of 98.19% with standard deviation of 0.6% of
pharmaceutical preparations and human serum, respectively. 相似文献
5.
Youssef AO 《Journal of fluorescence》2012,22(3):827-834
A new, simple, sensitive and selective spectrofluorimetric method for the determination of Hydrochlorothiazide was developed
in acetonitrile at pH 6.2. The Hydrochlorothiazide can remarkably enhance the luminescence intensity of the Tb3+ ion doped in sol–gel matrix at λex = 370 nm. The intensity of the emission band of Tb3+ ion doped in sol–gel matrix was increased due to the energy transfer from the triplet excited state of Hydrochlorothiazide
to (5D4) excited energy state of Tb3 ion. The enhancement of the emission band of Tb3+ ion doped in sol–gel matrix at (5D4→7 F5) 545 nm was directly proportion to the concentration of Hydrochlorothiazide with a dynamic ranges of 5.0 × 10−10—5.0 × 10−6 mol L−1 and detection limit of 2.2 × 10−11 mol L−1. 相似文献
6.
The fluorescence system of the norfloxacin-Tb3+- sodium dodecylbenzene sulfonate (SDBS) was investigated in this paper. The experiments indicated that the fluorescence intensity
of the Tb3+-SDBS was greatly enhanced by the norfloxacin. On the basis of the above findings, a sensitive fluorimetric method for determining
the norfloxacin was established. The fluorescence intensity was measured by a 1-cm quartz cell with the excitation wavelength
of 290 nm and the emission wavelength of 545 nm. The enhanced fluorescence intensity of the system (Δ F) showed a good linear
relationship with the concentration of norfloxacin in the range of 5.0×10−9 mol L−1–2.0×10−6 mol L−1, its correlation coefficient was 0.9991 and the detection limit (S/N=3) was 1.2×10−9 mol L−1. The presented method was used to determine the norfloxacin in real pharmaceutical samples. The luminescence mechanism was
also discussed in detail. In the fluorescence system of the norfloxacin-Tb3+-SDBS, the SDBS not only acted as the surfactant, but also acted as the energy donor. 相似文献
7.
A sensitive and selective method for the trace determination of 3, 3’, 4, 4’-tetrachlorobiphenyl (PCB77) by using bovine serum
albumin (BSA) as a fluorescence probe was introduced. Under optimum conditions, the enhanced fluorescence intensity was proportional
to the concentration of polychlorinated biphenyls in the range of 8.9 × 10−8–5.0 × 10−6 mol L−1 for PCB77, and 5.0 × 10−7–5.0 × 10−6 mol L−1 for 2, 2’, 5, 5’-tetrachlorbiphenyl (PCB52). The detection limits (S/N = 3) of PCB77 and PCB52 were 2.6 × 10−8 mol L−1 and 2.9 × 10−7 mol L−1, respectively. Furthermore, the fluorescence enhancement mechanism was discussed in detail. Results indicated that fluorescence
enhancement of the system originated from the formation of BSA-PCBs complexes. In addition, PCBs were mainly bound to the
tyrosine residues in BSA molecules. 相似文献
8.
R. H. Compton K. T. V. Grattan T. Morrow 《Applied Physics A: Materials Science & Processing》1980,22(3):307-311
The fundamental photophysical parameters of the organic scintillators, anthracene, 9, 10 dimethyl antracene (DMA), 9, 10 diphenyl
anthracene (DPA), 2-(1-napthyl)-5-phenyloxazole (α-NPO) and 2, 2′-p-phenyl bis (5-phenyloxazole) (POPOP), were investigated
in the liquid and vapour phases. Their ground state, triplet-triplet and fluorescence spectra were determined and accurate
extinction coefficients obtained. Photodecomposition of POPOP vapour under 337 nm excitation was investigated in detail and
a photodecomposition quantum yield of 1.1×10−2 obtained at 568 K. The POPOP triplet state in the vapour phase is quenched by the addition of 1, 3, 5, 7 cyclo-octatetraene
and a quenching rate constant of 2.9×1010 M−1 s−1 was determined. 相似文献
9.
A Ce(IV)-based reducing capacity (CERAC) assay was developed to measure the total antioxidant capacity (TAC) of foods, in
which Ce(IV) would selectively oxidize antioxidant compounds but not citric acid and reducing sugars which are not classified
as antioxidants. The method is based on the electron-transfer (ET) reaction between Ce(IV) ion and antioxidants in optimized
acidic sulphate medium (i.e., 0.3 M H2SO4 and 0.7 M Na2SO4) and subsequent determination of the produced Ce(III) ions by a fluorometric method. The fluorescent product, Ce(III), exhibited
strong fluorescence at 360 nm with an excitation wavelength of 256 nm, the fluorescence intensity being correlated to antioxidant
power of the original sample. The linear concentration range for most antioxidants was quite wide, e.g., 5.0 × 10−7–1.0 × 10−5 M for quercetin. The developed procedure was successfully applied to the TAC assay of antioxidant compounds such as trolox,
quercetin, gallic acid, ascorbic acid, catechin, naringin, naringenin, caffeic acid, ferulic acid, glutathione, and cysteine.
The proposed method was reproducible, additive in terms of TAC values of constituents of complex mixtures, and the trolox
equivalent antioxidant capacities (TEAC coefficients) of the tested antioxidant compounds gave good correlations with those
found by reference methods such as ABTS and CUPRAC. 相似文献
10.
11.
A new spectrofluorimetric method was developed for the determination of trace amounts of dopamine (DA). Using chlorosulfonylthenoyltrifluoroacetone
(CTTA)–europium ion (Eu3+) as a fluorescent probe, in a buffer solution at pH = 10.0, DA can remarkably enhance the fluorescence intensity of the CTTA-Eu3+ complex at λ = 612 nm; the enhanced fluorescence intensity of Eu3+ is proportional to the concentration of DA. Optimum conditions for the determination of DA were also investigated. The linear
range and detection limit for the determination of DA were 5.0 × 10−8∼1.6 × 10−5 mol/l and 3.2 × 10−8 mol/l. This method is simple, practical and relatively free of interference from coexisting substances, and can be applied
to assess DA in injection and human serum samples with good precision and accuracy. 相似文献
12.
In our study, terbium-acetylacetone (Tb-acac) composite nanoparticles have been prepared under vigorous ultrasonic irradiation.
The nanoparticles are water soluble, stable and have extremely narrow emission bands and high internal quantum efficiencies.
They were used as fluorescence probes in the determination of enoxacin (Enox) based on the fluorescence enhancement of nanoparticles
through fluorescence resonance energy transfer (FRET). The influence of buffer solution on the fluorescence intensity was
investigated. Under the optimum conditions, the fluorescence intensity of the Tb-acac-Enox system is linearly proportional
to the Enox concentration in the Enox concentration range of 2 × 10−7–1 × 10−4 M. The correlation coefficient for the calibration curve was 0.9976. The limit of detection as defined by IUPAC, C
LOD = 3S
b/m (where S
b is the standard deviation of the blank signals and m is the slope of the calibration graph) was found to be 3 × 10−8 M. The relative standard deviation (RSD) for six repeated measurements of 1 × 10−4 M Enox was 1.35%. The method was applied to the determination of Enox in pharmaceutical formulation and recovery results
were obtained from urine samples. 相似文献
13.
A new spectrofluorimetric method was developed for the determination of trace amount of 5-hydroxytryptamine (5-HT) in human
urine and serum samples. In the NaAc-HAc buffer solution of pH=5.80, 5-HT can react with formaldehyde-acetylacetone system
to form a new compound which sends yellow green fluorescence at 533nm and the enhanced fluorescence intensity is in proportion
to the concentration of 5-HT. Optimum conditions for the determination of 5-HT were also investigated. The dynamic range and
detection limit for the determination of 5-HT are 5.35×10−7∼1.07×10−4 mol/L and 2.08×10−7 mol/L, respectively. The developed method is simple, practical and can be successfully applied to determination of 5-HT in
human urine and serum samples. Moreover, the enhancement mechanisms of the fluorescence intensity in the 5-HT - formaldehyde-acetylacetone
system have been also discussed. 相似文献
14.
Yoshio Kobayashi Hidekazu Kakinuma Daisuke Nagao Yasuo Ando Terunobu Miyazaki Mikio Konno 《Journal of nanoparticle research》2009,11(7):1787-1794
This article describes a method for silica coating of Co–Pt alloy nanoparticles prepared in the presence of poly(vinylpyrrolidone)
(PVP) as a stabilizer. The Co–Pt nanoparticles were prepared in an aqueous solution at 25–80 °C from CoCl2 (3.0 × 10−4 M), H2PtCl6 (3.0 × 10−4 M), PVP (0–10 g/L), and NaBH4 (4.8 × 10−3–2.4 × 10−2 M). The silica coating was performed for the Co–Pt nanoparticle colloid containing the PVP ([Co] = [Pt] = 3.0 × 10−5 M) at 25 °C in (1/4) (v/v) water/ethanol solution with tetraethoxyorthosilicate (TEOS) (7.2 × 10−5–7.2 × 10−3 M) and ammonia (0.1–1.0 M). Silica particles, which had an average size of 43 nm and contained multiple cores of Co–Pt nanoparticles
with a size of ca. 8 nm, were produced at 1.4 × 10−3 M TEOS and 0.5 M ammonia after the preparation of Co–Pt nanoparticles at 80 °C, 5 g/L PVP, and 2.4 × 10−2 M NaBH4. Their core particles were fcc Co–Pt alloy crystallites. Their saturation magnetization was 2.0-emu/g sample, and their coercive
field was 12 Oe. 相似文献
15.
Water-soluble Mn2+-doped ZnS quantum dots (QDs) were prepared using mercaptoacetic acid as the stabilizer. The optical properties and structure
features were characterized by X-Ray, absorption spectrum, IR spectrum and fluorescence spectrum. In pH 7.8 Tris-HCl buffer,
the QDs emitted strong fluorescence peaked at 590 nm with excitation wavelength at 300 nm. The presence of sulfide anion resulted
in the quenching of fluorescence and the intensity decrease was proportional to the S2− concentration. The linear range was from 2.5 × 10−6 to 3.8 × 10−5 mol L−1 with detection limit as 1.5 × 10−7 mol L−1. Most anions such as F−, Cl−, Br−, I−, CH3CO2
−, ClO4
−, CO3
2−, NO2
−, NO3
−, S2O3
2−, SO3
2− and SO4
2− did not interfere with the determination. Thus a highly selective assay was proposed and applied to the determination of
S2− in discharged water with the recovery of ca. 103%. 相似文献
16.
A Tm, Mg co-doped LiTaO3 crystal has been grown by Czochralski method. Room temperature polarized absorption spectra and fluorescence spectrum of
the Tm, Mg:LiTaO3 crystal were measured and analyzed. The maximum absorption cross-section is 6.0791 × 10−20 cm2 at around 790 nm with full width at half maximum of 5 nm. The emission cross-section of 3
F
4 manifold was 2.2 × 10−20 cm2. The spectroscopic parameters of Tm3+ ion were calculated by applying the Judd-Ofelt approach, and the intensity parameters Ω2, Ω4, and Ω6 were obtained to be 7.71 × 10−20, 1.09 × 10−20, and 1.16 × 10−20 cm2, respectively. The branching ratios and radiative lifetimes were also presented and the radiative lifetime of Tm3+
3
F
4 → 3
H
6 transition is 968.3 μs. The results were also analyzed and compared with other Tm3+ doped hosts. 相似文献
17.
A novel, simple, sensitive and selective spectrofluorimetric method was developed for the determination of trace amounts of
chlorzoxazone and Ibuprofen in pharmaceutical tablets using optical sensor Eu-Tetracycline HCl doped in sol–gel matrix. The
chlorzoxazone or Ibuprofen can remarkably enhance the luminescence intensity of Eu-Tetracycline HCl complex doped in a sol–gel
matrix in dimethylformamide (DMF) at pH 9.7 and 6.3, respectively, λex = 400 nm. The enhancing of luminescence intensity peak of Eu-Tetracycline HCl complex at 617 nm is proportional to the concentration
of chlorzoxazone or Ibuprofen a result that suggested profitable application as a simple optical sensor for chlorzoxazone
or Ibuprofen assessment. The dynamic ranges found for the determination of chlorzoxazone and Ibuprofen concentration are 5 × 10−9–1 × 10−4 and 1 × 10−8–7 × 10−5 mol L−1, and the limit of detection (LOD) and quantitation limit of detection (LOQ) are 3.1 × 10−10 , 9.6 × 10−10 and 5.6 × 10−10, 1.7 × 10−9 mol L−1, respectively. 相似文献
18.
Y. H. Wang T. Liu R. Dumke A. Stejskal Y. N. Zhao J. Zhang Z. H. Lu L. J. Wang Th. Becker H. Walther 《Laser Physics》2007,17(7):1017-1024
We report on an improved absolute frequency measurement of the 5s
2 1
S
00-5s5p
3
P
0 narrowline clock transition at 236.5 nm, for a single, trapped, and laser-cooled 115In ion. Using a narrowline laser as the local oscillator, a linewidth of 43 Hz for the transition is resolved. The uncertainty
of the transition frequency’s centroid is 18 Hz, leading to a fractional uncertainty of 1.4 × 10−14. For absolute frequency measurement, we use an optical frequency comb locked to a cesium clock as the reference. The transition
frequency is found to be 1267402452900967(63) Hz, averaged over 13 days of separate measurements. The accuracy is about 5.0
× 10−14. We discuss possibilities for further improvement.
Original Text ? Astro, Ltd., 2007. 相似文献
19.
A. M. Efimov A. I. Ignat’ev N. V. Nikonorov E. S. Postnikov 《Optics and Spectroscopy》2011,111(3):426-433
We have measured the UV absorption spectra of photothermorefractive glasses of the system Na2O-ZnO-Al2O3-NaF-SiO2 doped by cerium oxide in the range of (2.8–5.0) × 104 cm−1 (360–200 nm). The spectra have been processed by the method of dispersion analysis based on the analytical convolution model
for the complex dielectric function of glasses. We show that the absorption band centered at 3.3 × 104 cm−1 (∼303 nm) that is attributed to the transition 2F
5/2 → 5d in the Ce3+ ion, is an envelope of three spectral components. The broad absorption range (3.5–4.7) × 104 cm−1 (200–270 nm) that is commonly interpreted as a charge transfer band of the Ce(IV) valence state, is an envelope of at least
three spectral components. 相似文献
20.
In the paper, a chemiluminescence (CL) system was developed based on the catalytical effect of diperiodatocuprate (III) (DPC)
on the 1,10-phenanthroline (phen)/hydrogen peroxide (H2O2) in the presence of cetyltrimethylammonium bromide (CTAB). The effects of experimental conditions were investigated. Meanwhile
the increase of CL intensity of the DPC/phen/H2O2/CTAB system is proportional to the concentration of phen in the range of low concentration. The linear range of the calibration
curve is 5.0 × 10−9–1.0 × 10−6 mol L−1, and the corresponding detection limit is 1.9 × 10−9 mol L−1. The effects of phenolic compounds (PCs) on the system were investigated. Hydroquinone was used as an example to investigate
the application of the CL system to the determination of PCs. The quenched CL intensity is linearly related to the logarithm
of concentration of hydroquinone. The linear range of the calibration curve is 2.5 × 10−9–1.0 × 10−5 g mL−1, and the corresponding detection limit is 1.8 × 10−9 g mL−1. This phen and hydroquinone can be synchronously determined. The method was applied to the determination of hydroquinone
in water samples and the recoveries were from 92% to 106%. 相似文献