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1.
In this work, a new simple and sensitive flow injection method is developed for the determination of homocysteine with spectrofluorimetric
detection technique. This method is based on the oxidation of homocysteine with Tl (III) in acidic media, producing fluorescence
reagent, TlCl32- (λex = 237 nm, λem = 419 nm). The effects of chemical parameters (including pH of the solutions, the buffer, Tl (III) and potassium chloride
concentrations), instrumental parameters (such as flow rate of the solutions, reaction coil length, and sample loop volume)
and temperature on the fluorescence intensity as an analytical signal are studied and optimized. In the optimum conditions
of the above variables, homocysteine can be determined in the range 4.0 × 10-7–40.0 × 10-6 M with the LDR from 4.0 × 10-7 to 25.0 × 10-6 M. The detection limit (with S/N = 3) is 6.0 × 10-8 M of homocysteine and precision for the injection of 5.0, 10.0 and 15.0 μM of homocysteine are 0.8%, 1.5% and 2.5% (n = 10) respectively. The rate of analysis is 90 samples per hour. The influence of potential interfering substances, including
amino acids and carbohydrates is also studied. The proposed method has been successfully used for the determination of homocysteine
in the real sample (blood serum and tap water) matrix. 相似文献
2.
A rapid, simple and sensitive spectrofluorimetric method for determination of trace amount of ofloxacin was developed. At
pH 5.1 the ofloxacin enhances the luminescence intensity of the Eu3+ ion in Eu3+- ofloxacin complex at λex = 365 nm. The produced luminescence intensity of Eu3+-ofloxacin complex was in proportional to the concentration of ofloxacin. The working range for the determination of ofloxacin
was 5.0 × 10-9–5.0 × 10-6 mol L-1 with lower detection limit (LOD) and quantitative detection limit (QDL) of 3 × 10-9 and 9 × 10-9 mol L-1, respectively. The enhancement mechanism of the luminescence intensity in the Eu3+-ofloxacin system has been also explained. The method revealed good selectivity for ofloxacin in the presence of coexisting
substances and used successfully for the assay of ofloxacin in pharmaceutical preparations and serum. A comparison with other
standard methods was also discussed. 相似文献
3.
T. Gasmi H.A. Zeaiter G. Ropero A. González Urena 《Applied physics. B, Lasers and optics》2000,71(2):169-175
This paper presents the construction, use and characterisation of a laser-induced sealed plasma shutter to clip off the nitrogen
pulse tail of a CO2-TEA laser-based lidar dial system. Investigation of the optimum gas filling pressure, temporal profile of the clipped pulse,
and the laser threshold power intensities to achieve ionisation growth and breakdown in helium, argon, and nitrogen are also
presented. Values of these power density thresholds lie between 3×1011 W cm-2–5×1012 W cm-2, 2×1011 W cm-2–2×1012 W cm-2 and 3×1013 W cm-2–2×1014 W cm-2 for helium, argon, and nitrogen, respectively. The range resolution attainable with the present clipped pulses is 15 m, which
is 30 times better than that readily obtained with the nitrogen-tailed pulses. Field measurements of the lidar returns with
the clipped pulse from a co-operative target are presented.
Received: 27 December 1999 / Revised version: 11 February 2000 / Published online: 27 April 2000 相似文献
4.
Attia MS Mahmoud WH Ramsis MN Khalil LH Othman AM Hashem SG Mostafa MS 《Journal of fluorescence》2011,21(4):1739-1748
A simple and sensitive spectrofluorimetric method for determination of trace amount of doxycycline hydrochloride (DC) in pharmaceutical
tablets and serum samples was developed. In ammonia buffer solution of pH 8.9 the doxycycline hydrochloride can remarkably
enhance the luminescence intensity of the Sm3+ ion in Sm3+- DC complex at λex = 400 nm. The produced luminescence intensity of Sm3+- DC complex in DMSO is in proportion to the concentration of DC and used as optical sensor for its determination. The dynamic
range for the determination of DC is 1 × 10−8 – 5 × 10−6 mol L−1 and in case of quantum yield calculations is 7 × 10−9 – 5 × 10−6 mol L−1 with detection limit of 6.5 × 10−10 mol L−1. The enhancement mechanism of the luminescence intensity in the Sm3+- DC system has been also discussed. A comparison with other spectrofluorimetric methods for tetracycline derivatives in which
Eu3+ ion is used instead of Sm3+ ion is also studied. 相似文献
5.
I. A. Andreyev 《Technical Physics》2006,51(1):121-125
The variation of the resonance frequency of piezoelectric resonators subjected to a constant electric field is demonstrated
with longitudinal vibrations in La3Ga5SiO14 (langasite) crystal rods at temperatures between −60 and +80°C. For the rods whose longtudinal axis makes angle α with the
crystal axis
in the plane of the axes
and [0001], the change in the frequency is proportional to the field strength and depends on α. For a field of ±1.5 × 106 V/m and α = 15°, the relative change in the frequency is ±120 × 10−6. It is shown that La3Ga5SiO14 crystals offer a set of physical parameters that makes them promising for electrically controlled acoustoelectronic devices
and for devices based on nonlinear interaction between acoustic waves. 相似文献
6.
V.A. Kapitanov Yu.N. Ponomarev K. Song H.K. Cha J. Lee 《Applied physics. B, Lasers and optics》2001,73(7):745-750
The results of theoretical and experimental studies of sensitivity of a resonant photoacoustic Helmholtz resonator detector
for gas flowing through a photoacoustic cell under reduced pressure are presented. The measurements of the sensitivity and
ultimate sensitivity of the differential photoacoustic cell were performed with a near-IR room-temperature diode laser using
the well-known H2O absorption line (12496.1056 cm-1) as a reference. The measured value of the sensitivity (6–17 Pa W m-1) is in satisfactory agreement with the calculated one, which equals 6–35 Pa W m-1. The obtained value of the ultimate sensitivity ((3–5)×10-7 W m-1 Hz-1/2) provides measurements of the concentration of molecules at the ppb–ppm level.
Received: 19 April 2001 / Revised version: 18 September 2001 / Published online: 7 November 2001 相似文献
7.
M.?Cristina?Gon?alves Verónica?de?Zea Bermudez M.?M.?Silva M.?J.?Smith Enrique?Morales Rute?A.?Sá Ferreira Luís?D.?Carlos 《Ionics》2010,16(3):193-201
Variable chain length di-urethane cross-linked poly(oxyethylene) (POE)/siloxane hybrid networks were prepared by application
of a sol-gel strategy. These materials, designated as di-urethanesils (represented as d-Ut(Y′), where Y′ indicates the average
molecular weight of the polymer segment), were doped with lithium triflate (LiCF3SO3). The two host hybrid matrices used, d-Ut(300) and d-Ut(600), incorporate POE chains with approximately 6 and 13 (OCH2CH2) repeat units, respectively. All the samples studied, with compositions ∞ > n ≥ 1 (where n is the molar ratio of (OCH2CH2) repeat units per Li+), are entirely amorphous. The di-urethanesils are thermally stable up to at least 200 °C. At room temperature the conductivity
maxima of the d-Ut(300)- and d-Ut(600)-based di-urethanesil families are located at n = 1 (approximately 2.0 × 10−6 and 7.4 × 10−5 Scm−1, respectively). At about 100 °C, both these samples also exhibit the highest conductivity of the two electrolyte systems
(approximately 1.6 × 10−4 and 1.0 × 10−3 Scm−1, respectively). The d-Ut(600)-based xerogel with n = 1 displays excellent redox stability. 相似文献
8.
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
9.
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
10.
In the present study, a kind of solid polymer electrolyte (SPE) based on poly(vinylidene difluoride-co-hexafluoropropylene)/poly(methyl methacrylate) blends was prepared by a casting method to solve the safety problem of lithium
secondary batteries. Owing to being plasticized with a room temperature ionic liquid, N-butyl-N′-methyl-imidiazolium hexafluorophosphate, the obtained SPE shows a thermal decomposition temperature over 300°C and an ionic
conductivity close to 10−3 S cm−1. The SPE-3 sample, in which the weight of two polymers is equivalent, possesses an ionic conductivity of 0.45 × 10−3 S cm−1 at 25°C and presents an electrochemical window of 4.43 V. The ionic conductivity of the SPE-3 is as high as 1.73 × 10−3 S cm−1 at 75°C approaching to that of liquid electrolyte. The electrochemical performances of the Li/LiFePO4 cells confirmed its feasibility in lithium secondary batteries. 相似文献
11.
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
12.
《The European Physical Journal C - Particles and Fields》2008,54(1):61-72
Results of background measurements with a prototype of the Borexino detector were used to search for 478 keV solar axions
emitted in the M1-transitions of 7Li*. The Compton conversion of axion to a photon A+e→e+γ, axioelectric effect A+e+Z→e+Z, decay of axion in two photons A→2γ and
Primakoff conversion on nuclei A+Z→γ+Z are considered. The upper limit on constants of interaction of axion with electrons,
photons and nucleons – gAegAN≤(1.0–2.4)×10-10 at mA≤450 keV and gAγgAN≤5×10-9 GeV-1 at mA≤10 keV are obtained (90%c.l.). For heavy axions with mass at 100<mA<400 keV the limits gAe<(0.7–2.0)×10-8 and gAγ<10-9–10-8 are obtained in assumption that gAN depends on mA as for KSVZ axion model. These limits are stronger than obtained in previous laboratory-based experiments using nuclear reactor
and artificial radioactive sources.
PACS 14.80.Mz; 29.40.Mc; 26.65.+t 相似文献
13.
Alonso A Almendral MJ Curto Y Criado JJ Rodríguez E Manzano JL 《Journal of fluorescence》2007,17(4):390-400
The flow injection technique is applied to study the binding to DNA of new platinum complexes—E1: ethylenediaminechlorocholylglycinateplatinum(II): [PtCl(CG)(en)], C54H92O12Pt and E2: ethylenediaminebischolylglycinateplatinum(II): [Pt(CG)2(en)], C28H50ClN3O6Pt—derived from cisplatin in which the exchangeable ligands were replaced by bile acids, such that these anticancer drugs
have less toxicity and less resistance is developed towards them. Both compounds are fluorescent and their fluorescence is
enhanced when they form adducts with DNA, a property that is extremely useful for monitoring the cytotoxic activity and their
mechanisms of action. The binding parameters to DNA of E1 [apparent intrinsic binding constant KE1: (11.2 ± 0.4) × 103 M−1 and maximum number of binding sites per nucleotide, n
E1: 0.121 ± 2 × 10−3) and E2 (KE2: 9.2 ± 0.7) × 103 M−1 and n
E2 0.098 ± 2 × 10−3] were determined following the Scatchard method and the type of binding was studied experimentally through the modifications
introduced by each of the compounds into the ethidium bromide–DNA bond. 相似文献
14.
X. Hao J. Ma D. Zhang X. Xu Y. Yang H. Ma S. Ai 《Applied Physics A: Materials Science & Processing》2002,75(3):397-399
Transparent conducting antimony-doped tin oxide (SnO2:Sb) films were deposited on organic substrates by r.f. magnetron-sputtering. Polycrystalline films with a resistivity of
≈ 6.5×10-3 Ω cm, a carrier concentration of≈ 1.2×1020 cm-3 and a Hall mobility of ≈ 9.7 cm2 v-1 s-1 were obtained. The average transmittance of these films reached 85% in the wavelength range of the visible spectrum.
Received: 20 April 2001 / Accepted: 23 July 2001 / Published online: 17 October 2001 相似文献
15.
R.A. Graham 《Solid State Communications》1973,12(6):503-506
Measurements of the piezoelectric polarization of z-cut lithium niobate are accomplished for dynamic compressive strains of from 8.9 × 10?4 to 6 × 10?3. Values for the linear piezoelectric constant, 33 and its strain derivative are determined. The logarithmic strain derivatives of the longitudinal piezoelectric constants of x-cut quartz and z-cut lithium niobate are found to be approximately equal. 相似文献
16.
Hosseini M Ganjali MR Tavakoli M Norouzi P Faridbod F Goldooz H Badiei A 《Journal of fluorescence》2011,21(4):1509-1513
A novel and simple fluorescence enhancement method for selective pyrophosphate(PPi) sensing was proposed based on a 1:1 metal
complex formation between bis(8-hydroxy quinoline-5-solphonat) chloride aluminum(III) (Al(QS)2Cl), (L) and PPi in aqueous solution. The linear response range covers a concentration range of 1.6 × 10−7 to 1.0 × 10−5 mol/L of PPi and the detection limit of 2.3 × 10−8 mol/L. The association constant of L-PPi complex was calculated 2.6 × 105 L/mol. L was found to show selectively and sensitively fluorescence enhancement toward PPi over than I3-, NO3-, CN−, CO32−, Br−, Cl−, F−, H2PO4− and SO42−, which was attributed to higher stability of inorganic complex between pyrophosphate and L. 相似文献
17.
A. D. Khrycheva D. A. Nedosekin M. Yu. Kononets M. A. Proskurnin S. V. Pakhomova W. Faubel S. Heissler 《The European physical journal. Special topics》2008,153(1):41-44
Photothermal deflection spectroscopy was applied for
selective detection of the intensely coloured iron(II) chelate with
ferrozine on Silufol plates. The linearity range was 1×10-11 - 6×10-8 mol cm-2
of chelate at the plate surface, which corresponded to 1×10-9 - 4×10-6 M of chelate in
solution. The limits of detection and quantification are 8×10-12 and 20×10-12 mol cm-2
at the plate from 15 μL of test solution (0.5 nM and 1.5 nM in
solution, respectively), which corresponded to n ×10-18 mol absolute amounts of the chelate at the detection
zone. 相似文献
18.
《The European Physical Journal C - Particles and Fields》2007,52(2):255-265
The longitudinal double spin asymmetry A1
ρ for exclusive leptoproduction of ρ0 mesons, μ+N→μ+N+ρ, is studied using the COMPASS 2002 and 2003 data. The measured reaction is incoherent exclusive ρ0 production on polarised deuterons. The Q2 and x dependence of A1
ρ is presented in a wide kinematical range, 3×10-3<Q2< 7 (GeV/c)2 and 5×10-5<x<0.05. The results presented are the first measurements of A1
ρ at small Q2 (Q2< 0.1 (GeV/c)2) and small x (x<3×10-3). The asymmetry is in general compatible with zero in the whole kinematical range.
PACS 13.60.Le; 13.88.+e 相似文献
19.
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
20.
The efficiency of excited-state interaction between Tb3+ and the industrial product Cilostazol (CIL) has been studied in different solvents. High luminescence intensity peak at 545 nm
of terbium complex in acetonitrile was obtained. The photophysical properties of the green emissive Tb3+ complex have been elucidated, the terbium was used as optical sensor for the assessment of CIL in the pharmaceutical tablets
and body fluids at pH 3.1 and λex = 320 nm with a concentration range 1.0 × 10−9–1.0 × 10−6 mol L−1 of CIL, correlation coefficient of 0.998 and detection limit of 7.5 × 10−10 mol L−1. 相似文献