共查询到20条相似文献,搜索用时 203 毫秒
1.
Two simple, sensitive and specific fluorimetric methods have been developed for the determination of some sulphur containing
compounds namely, Acetylcysteine (Ac), Carbocisteine (Cc) and Thioctic acid (Th) using terbium Tb+3 and uranium U+3 ions as fluorescent probes. The proposed methods involve the formation of a ternary complex with Tb+3 in presence of Tris-buffer method (I) and a binary complex with aqueous uranyl acetate solution method (II). The fluorescence
quenching of Tb+3 at 510, 488 and 540 nm (λex 250, 241 and 268 nm) and of uranyl acetate at 512 nm (λex 240 nm) due to the complex formation was quantitatively measured for Ac, Cc and Th, respectively. The reaction conditions
and the fluorescence spectral properties of the complexes have been investigated. Under the described conditions, the proposed
methods were applicable over the concentration range (0.2–2.5 μg ml−1), (1–4 μg ml−1) and (0.5–3.5 μg ml−1) with mean percentage recoveries 99.74±0.36, 99.70±0.52 and 99.43±0.23 for method (I) and (0.5–6 μg ml−1), (0.5–5 μg ml−1), and (1–6 μg ml−1) with mean percentage recoveries 99.38±0.20, 99.82±0.28 and 99.93±0.32 for method (II), for the three cited drugs, respectively.
The proposed methods were successfully applied for the determination of the studied compounds in bulk powders and in pharmaceutical
formulations, as well as in presence of their related substances. The results obtained were found to be in agree statistically
with those obtained by official and reported ones. The two methods were validated according to USP guidelines and also assessed
by applying the standard addition technique. 相似文献
2.
A rapid, simple and highly sensitive second derivative synchronous fluorometric method has been developed for the simultaneous
analysis of binary mixture of cinnarizine (CN) and domperidone (DOM). The method is based upon measurement of the native fluorescence
of these drugs at Δλ = 80 nm in aqueous methanol (50% V/V). The different experimental parameters affecting the native fluorescence
of the studied drugs were carefully studied and optimized. The fluorescence-concentration plots were rectilinear over the
range of 0.1 to 1.3 μg mL−1 and 0.1–3.0 μg mL−1 for CN and DOM, respectively with lower detection limits of 0.017 and 5.77 × 10−3 μg mL−1 and quantification limits of 0.058 and 0.02 μg mL−1 for CN and DOM. The proposed method was successfully applied for the determination of the studied compounds in synthetic
mixtures and in commercial tablets. The results obtained were in good agreement with those obtained with reference methods.
The high sensitivity attained by the synchronous fluorometric method allowed the determination of CN in real and spiked human
plasma. The mean % recoveries in case of spiked human plasma (n = 3) were 96.39 ± 1.18 while that in real human plasma (n = 3) was 104.67 ± 4.16. 相似文献
3.
A sensitive, simple and selective spectrofluorimetric method was developed for the determination of oxamniquine (OXM) in pharmaceutical
formulations and biological fluids. The method is based on the reaction between the drug and 1-dimethylaminonaphthalene-5-sulphonyl
chloride (dansyl chloride) in presence of 0.5 M sodium carbonate (pH 10) to yield a highly fluorescent derivative that is
measured at 445 nm after excitation at 335 nm. The different experimental parameters affecting the development and stability
of the reaction product were carefully studied and optimized. The fluorescence concentration plot was rectilinear over the
range of 0.02–0.2 μg ml−1 with a lower detection limit (LOD) of 0.007 μg ml−1 and limit of quantitation (LOQ) of 0.02 μg ml−1. The proposed method was successfully applied to the analysis of commercial capsules. The results obtained were in good agreement
with those obtained using the official spectrophotometric method. Furthermore, the method was applied for the determination
of oxamniquine in spiked human plasma, the mean % recovery (n = 4) is 97.77 ± 1.19. A proposal of the reaction pathway was presented. 相似文献
4.
M. Bryushinin V. Golubev Y. Kumzerov D. Kurdyukov I. Sokolov 《Applied physics. B, Lasers and optics》2009,95(3):489-495
We report an experimental investigation of the non-steady-state photoelectromotive force in nanostructured GaN within porous
glass and polypyrrole within chrysotile asbestos. The samples are illuminated by an oscillating interference pattern created
by two coherent light beams and the alternating current is detected as a response of the material. Dependences of the signal
amplitude versus temporal and spatial frequencies, light intensity, and temperature are studied for two wavelengths λ=442 and 532 nm. The conductivity of the GaN composite is measured: σ=(1.1–1.6)×10−10 Ω−1 cm−1 (λ=442 nm, I
0=0.045–0.19 W/cm2, T=293 K) and σ=(3.5–4.6)×10−10 Ω−1 cm−1 (λ=532 nm, I
0=2.3 W/cm2, T=249–388 K). The diffusion length of photocarriers in polypyrrole nanowires is also estimated: L
D=0.18 μm. 相似文献
5.
Liu JM Gao F Gao WY Zeng LQ Huang XM Li ZM Huang XC Lin WN Wang FM Nie CL 《Journal of fluorescence》2008,18(2):573-579
When 1.00 mol l−1 I− is used as ion perturber, rhodamine 6G (Rh 6G) can emit strong and stable room temperature phosphorescence (RTP) on filter
paper substrate in KHC8H4O4–HCl buffer solution (pH = 3.50), heated at 70 °C for 10 min. NaIO4 can oxidize Rh 6G, which makes the RTP signal quench. Terbutaline sulfate (TBS) can inhibit NaIO4 from oxidizing Rh 6G, which makes the RTP signal of Rh 6G enhance sharply. The content of TBS is linear correlation to ΔIp of the system. Based on the facts above, a new inhibition solid substrate-room temperature phosphorimetry (SS-RTP) for the
determination of trace TBS has been established. The linear range of this method is 0.0104–2.08 pg spot−1 (corresponding concentration: 0.026–5.2 ng ml−1, with a sample volume of 0.4 μl) with a detection limit (L.D.) of 2.6 fg spot−1 (corresponding concentration: 6.5 × 10−12 g ml−1), and the regression equation of working curve is ΔIp = 2.040 + 54.54 mTBS (pg spot−1), n = 6, correlation coefficient is 0.9994. For the samples containing 0.0104 pg spot−1 and 2.08 pg spot−1 TBS, the relative standard deviation (RSD) are 3.8% and 2.3% (n = 8), respectively, indicating good precision. This method has been applied to determination of trace TBS in the practical
samples with satisfactory results. The reaction mechanism of NaIO4 oxidizing Rh 6G to inhibit SS-RTP for the determination of trace TBS is also discussed. 相似文献
6.
Belal TS 《Journal of fluorescence》2008,18(5):771-780
A simple, rapid, selective and sensitive spectrofluorimetric method was described for the analysis of three nitrofuran drugs,
namely, nifuroxazide (NX), nitrofurantoin (NT) and nitrofurazone (NZ). The method involved the alkaline hydrolysis of the
studied drugs by warming with 0.1 M sodium hydroxide solution then dilution with distilled water for NX or 2-propanol for
NT and NZ. The formed fluorophores were measured at 465 nm (λ
Ex 265 nm), 458 nm (λ
Ex 245 nm) and 445 nm (λ
Ex 245 nm) for NX, NT and NZ, respectively. The reaction pathway was discussed and the structures of the fluorescent products
were proposed. The different experimental parameters were studied and optimized. Regression analysis showed good correlation
between fluorescence intensity and concentration over the ranges 0.08–1.00, 0.02–0.24 and 0.004–0.050 μg ml−1 for NX, NT and NZ, respectively. The limits of detection of the method were 8.0, 1.9 and 0.3 ng ml−1 for NX, NT and NZ, respectively. The proposed method was validated in terms of accuracy, precision and specificity, and it
was successfully applied for the assay of the three nitrofurans in their different dosage forms. No interference was observed
from common pharmaceutical adjuvants. The results were favorably compared with those obtained by reference spectrophotometric
methods. 相似文献
7.
Three sensitive and selective new alternatives for fluorometric determination of cerium(III) are described in this study.
Ce(III) is highly fluorescent in sodium pyrophosphate, sodium trimetaphosphate, and sodium tetrametaphosphate solutions. For
these reagents, the maximum excitation/emission wavelengths are 300/350, 297/340, and 299/352 nm, respectively. Maximum fluorescence
intensities are obtained by irradiating Ce(III) dissolved in 0.033 g L−1 sodium pyrophosphate, 41.4 g L−1 sodium trimetaphosphate, and 0.96 g L−1 sodium tetrametaphosphate at room temperature. The fluorescence intensities are linear over the range 0.001–30, 0.001–75,
and 0.001–70 μg ml−1. The detection limits are calculated as 9.5 × 10−3, 1.1/10−3, and 3.8 × 10-3 μg ml−1 Ce(III), respectively. The relative standard deviations for 15/0.05 Μg ml−1 Ce(III) are 1.1/1.2, 1/1.1, and 1.2/1.3%, respectively. Quenching effects of other lanthanides and some inorganic anions
were investigated. The methods have been applied to rare earth mixtures with a good accuracy. 相似文献
8.
A highly sensitive flow-injection spectrofluorimetric method is presented for the rapid and simple determination of Hg (II)
in environmental and pharmaceutical samples. Murexide (ammonium purpurate) was used as the fluorescence reagent in the carrier
stream. An emission peak of murexide, which is decreased linearly by addition of Hg (II), occurs at 435 nm in aqueous solution
with excitation at 335 nm. A linear calibration was obtained for 5–200 ng ml−1 Hg (II) with the relative standard deviation 2.5% (n = 5) for a 20 μl injection volume Hg (II). The limit of the detection was 1 ng ml−1 and the sampling rate was 80 h−1. No significant interference was found by the ions commonly found in the most environmental samples. The proposed method
was successfully applied for the determination of trace mercury in real samples and the validation of the proposed methodology
is provided. 相似文献
9.
The results of an experiment measuring the difference Δλ=λa−λ m of the beta-decay constants of atomic and molecular tritium are reported. The difference Δλ is determined by comparing the
rates of growth of the relative content of radiogenic helium-3 in samples containing atomic and molecular tritium. The result
Δλ=(4.6±0.8)×10−12s−1 corresponds to a relative change of the decay constant by ∼0.26%.
Pis’ma Zh. éksp. Teor. Fiz. 68, No. 3, 167–170 (10 August 1998) 相似文献
10.
Liu JM Wu RH Li DC Zhou P Zheng MM Zeng XY Liu DX Huang XM Zhu GH 《Journal of fluorescence》2006,16(5):625-630
A new method for the determination of trace mercury by solid substrate-room temperature phosphorimetry (SS-RTP) quenching method has been established. In glycine-HCl buffer solution, xylenol orange (XO) can react with Sn4+ to form the complex [Sn(XO)6]4+. [Sn(XO)6]4+ can interact with Fin− (fluorescein anion) to form the ion associate [Sn(XO)6]4+·[(Fin)4]−, which can emit strong and stable room temperature phosphorescence (RTP) on polyamide membrane (PAM). Hg2+ can catalyze H2O2 oxidizing the ion association complex [Sn(XO)6]4+·[(Fin)4]−, which causes the RTP to quench. The ΔIp value is directly proportional to the concentration of Hg2+ in the range of 0.016–1.6 fg spot−1 (corresponding concentration: 0.040–4.0 pg ml−1, 0.40 μl spot−1), and the regression equation of working cure is ΔIp=10.03+83.15 m Hg2+ (fg spot−1), (r=0.9987, n=6) and the detection limit (LD) is 3.6 ag spot−1(corresponding concentration: 9.0×10–15 g ml−1, the sample volume: 0.4 μl). This simple, rapid, accurate method is of high selectivity and good repeatability, and it has been successfully applied to the determination of trace mercury in real samples. The reaction mechanism for catalyzing H2O2 oxidizing the ion association complex ([Sn(XO)6]4+·[(Fin)4]−) SS-RTP quenching method to determine trace mercury is also discussed. 相似文献
11.
Zhuming Wang Xijuan Tan Donghua Chen Qiaoli Yue Zhenghua Song 《Journal of fluorescence》2009,19(5):801-808
It was first found that the intrinsic fluorescence of lysozyme at 340 nm can be quenched by cephalosporin analogues through
the static quenching and non-radiative energy transferring procedure. In the acetate buffer solution with pH 7.0 and 298 K,
the quenching fluorescence intensity was in a good linearity over the concentration of drugs in the range of 1–100 μmol L−1, 0.1–100 μmol L−1, 0.5–100 μmol L−1 and 0.05–100 μmol L−1 for cefradine, cefuroxime, cefotaxime and ceftriaxone, respectively. The quenching ability or the binding ability of the
studied drugs followed the pattern: ceftriaxone > cefotaxime > cefuroxime > cefradine, which was close to the order of their
antibacterial ability. The binding parameters including the association constant and the number of binding potential point
were calculated at different temperatures (288, 298 and 308 K), and thermodynamic parameters ΔH°, ΔS° and ΔG° were given. The binding mode of lysozyme with cephalosporins showed that the hydrophobic effect might play a major role.
The binding distance between cephalosporin and tryptophan residue in lysozyme was obtained. The results provided the quantitative
information for the binding of cephalosporin to lysozyme, and it was suggested that the drugs probably bound to the active
site near Trp62 in lysozyme. 相似文献
12.
Yu. A. Akulov 《Technical Physics》1999,44(9):1018-1020
The results of the first experiment designed to measure the difference between the beta-decay constants of atomic and molecular
tritium Δλ=λa–λm are presented. The experimental scheme calls for the creation of two identical samples of a gas mixture containing helium-4
and molecular tritium followed by the treatment of one of them for the purpose of bringing the tritium into the atomic state.
The value of Δλ is determined by comparing the growth rates of the ratio of the concentration of radiogenic helium-3 to the
concentration of helium-4 in the samples with molecular and atomic tritium. The value Δλ=(4.6±0.8)×10−12 s−1, which corresponds o a relative change in the decay constant amounting to ∼0.26%, is obtained.
Zh. Tekh. Fiz. 69, 19–21 (September 1999) 相似文献
13.
K. R. Allakhverdiev M. Ö. Yetis T. K. Baykara S. M. T. Özbek E. Yu. Salaev 《Laser Physics》2011,21(3):598-600
Two methods of preparation of the devices for visualization of pulsed and continuous near-IR (near infrared) are described
and the results of conversion of pulsed and continuous IR (800–1360 nm) laser radiation into the visible range of spectra
(400–680 nm) by using a transparent substrate covered with the particles (including nanoparticles) of effective nonlinear
materials of GaSe
x
S1 − x
(0.2 ≤ x ≤ 0.8) are presented. Converted light can be detected in transmission or reflection geometry as a visible spot corresponding
to the real size of the incident laser beam. Developed device structures can be used for checking if the laser is working
or not, for optical adjustment, for visualization of distribution of laser radiation over the cross of the beam and for investigation
of the content of the laser radiation. Low energy (power density) limit for visualization of the IR laser pulses with 2–3
ps duration for these device structures are: between 4.6–2.1 μJ (3 × 10−4−1 × 10−4 W/cm2) at 1200 nm; between 8.4–2.6 μJ (4.7 × 10−4−1.5 × 10−4 W/cm2) at 1300 nm; between 14.4–8.1 μJ (8.2 × 10−4–4.6 × 10−4 W/cm2) at 1360 nm. Threshold damage density is more than 10 MW/cm2 at λ = 1060 nm, pulse duration τ = 35 ps. The results are compared with commercially existing laser light visualizators. 相似文献
14.
W. J. Kossler X. H. Yu A. Greer H. E. Schone C. E. Stronach M. Davis R. S. Cary J. E. Crow W. F. Lankford J. Oostens 《Hyperfine Interactions》1991,63(1-4):81-86
Transverse and zero-field μSR measurements were made on YBa2(Cu1−xNix)3O7−y withx=0.1 and 0.2, and YBa2(Cu1−x
Zn
x
)3O7−y
withx=0.03, 0.06, 0.1, and 0.16, wherey≈0.1. Since doping may lead to magnetic ordering this was searched for with both zero and transverse field μSR, but no evidence
was found over the temperature range studied: 10–100 K. However, depolarization rates as functions of temperature were obtained,
and the low temperature values of these are σ=3.2 μs−1.1.6μs−1, and 1 μs−1 forx=0.01, and 0.2 Ni, respectively, and σ=0.8 μs−1, 0.75 μs−1, 0.65 μs−1, and 0.4 μs−1 forx=0.03, 0.06, 0.1, and 0.16 Zn, respectively. Estimates for the effect of decreasing electron concentration for Zn are made,
but these alone do not account for the drop in σ. Estimates for the effect of scattering on λ and hence σ are made. The reduction
in σ for Ni dopant is in surprisingly good agreement with these estimates. For Zn the order of magnitude is correct, but the
relative lack of further change in σ after the effect of the first 0.03 addition seems to imply a saturation of the effect
of scattering. 相似文献
15.
Hiroshi Isozaki 《Communications in Mathematical Physics》2001,222(2):371-413
We construct a generalized Fourier transformation ℱ(λ) associated with the 3-body Schr?dinger operator H=−Δ+Σ
a
V
a
(x
a
) and characterize all solutions of (H−λ)u= 0 in the Agmon–H?rmander space ℬ* as the image of ℱ(λ)*. These stationary solutions admit asymptotic expansions in ℬ* in terms of spherical waves associated with scattering channels.
Received: 20 September 2000 / Accepted: 20 May 2001 相似文献
16.
Nahed M. El-Enany Dina T. El-Sherbiny Amina A. Abdelal Fathalla F. Belal 《Journal of fluorescence》2010,20(2):463-472
A sensitive, simple and selective spectrofluorimetric method was developed for the determination of Lamotrigine (LMT) in pharmaceutical
formulations and biological fluids. The method is based on reaction of LMT with o-phthalaldehyde in presence of 2-mercaptoethanol in borate buffer of pH 9.8 to yield a highly fluorescent derivative that
is measured at 448 nm after excitation at 337 nm. The different experimental parameters affecting the development and stability
of the reaction product were carefully studied and optimized. The fluorescence-concentration plot was rectilinear over the
range of 0.1–1.0 μg ml−1 with lower limit of detection (LOD) 0.02 μg ml−1 and limit of quantification (LOQ) 0.06 μg ml−1 respectively. The proposed method was successfully applied to the the analysis of commercial tablets. Statistical comparison
of the results obtained by the proposed and reference method revealed no significant difference in the performance of the
two methods regarding the accuracy and precision respectively. The proposed method was further extended to the in-vitro and in-vivo determination of the drug in spiked and real human plasma. The mean percentage recoveries in spiked and real human plasma
(n = 3) were 95.78 ± 1.37 and 90.93 ± 2.34 respectively. Interference arising from co-administered drugs was also studied. A
proposal for the reaction pathway with o-phthalaldehyde was postulated. 相似文献
17.
S. F. Baranovsky P. A. Bolotin M. P. Evstigneev D. N. Chernyshev 《Journal of Applied Spectroscopy》2009,76(1):132-139
Two component (ethidium bromide–caffeine, ethidium bromide–DNA) and three component (ethidium bromide–caffeine–DNA) systems
in aqueous saline (0.01 M NaCl) phosphate buffer solutions (pH 6.86, T = 298 K) are studied spectrophotometrically. The equilibrium constants for dimerization of caffeine, K
D
= 1.22 ± 2 M−1, and for heteroassociation of ethidium bromide with caffeine, K = 71 ± 8 M−1, in ethidium bromide–caffeine systems are determined. When the concentration of caffeine is increased, the dynamic equilibrium
of the solution shifts toward formation of heterocomplexes which are, presumably, stabilized by dispersive and hydrophobic
interactions of chromophores. The equilibrium parameters for ethidium bromide complex formation with DNA are calculated: the
coupling constant for the dye with the biopolymer, K
1 = (232 ± 16)⋅103 M−1, and the number of base pairs of the biopolymer participating in bonding with the ligand, n
1 = 3.6 ± 0.2, are calculated. Given these values, it is suggested that under these experimental conditions there are two types
of bonding between ethidium bromide and the nucleic acid — intercalation and “external” bonds. A McGhee–von Hippel model for
a three component system and the numerical values of the parameters for molecular complex formation in two component systems
are used to calculate the bonding constant for caffeine with DNA, K
2 = 127 ± 30 M−1, and the number of base pairs of DNA which bond with caffeine, n
2 = 1.7 ± 0.2. The concentrations of ethidium bromide and caffeine in the composition of two and three component complexes
are calculated as functions of the nucleic acid content in the solution. An analysis of the concentration dependences shows
that heteroassociation of ligands has a significant effect on the reduction in the concentration of ethidium bromide–DNA complexes
in a three component system for low DNA concentrations, while at high DNA concentrations the bonding of caffeine with the
biopolymer has this effect.
Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 76, No. 1, pp. 143–151, January–February 2009. 相似文献
18.
D. R. El-Wasseef D. T. El-Sherbiny M. A. Abu-El-Enein S. M. El-Ashry 《Journal of fluorescence》2009,19(5):817-828
A rapid, simple and highly sensitive first derivative synchronous spectrofluorimetric method was developed for the simultaneous
analysis of a binary mixture of labetalol HCl (LBT) and furosemide (FUR) without prior separation. The method was based upon
measuring the first derivative of synchronous fluorescence spectra of the two drugs at Δλ =130 nm in aqueous ethanol (55%
V/V). The different experimental parameters affecting the synchronous fluorescence of the studied drugs were carefully studied
and optimized. The first derivative amplitude-concentration plots were rectilinear over the range of 0.10 to 1.00 μg/mL and
0.05–0.50 μg/mL with lower detection limits of 0.0149 and 7×10−3 μg/mL and quantification limits of 0.045 and 0.021 μg/mL for LBT and FUR, respectively. The proposed method was successfully
applied for the determination of the studied drugs in synthetic mixtures. The results obtained were in good agreement with
those obtained by the reference methods. 相似文献
19.
F. Kottmann W. Amir F. Biraben C. A. N. Conde S. Dhawan T. W. Hänsch F. J. Hartmann V. W. Hughes O. Huot P. Indelicato L. Julien P. Knowles S. Kazamias Y.-W. Liu F. Mulhauser F. Nez R. Pohl P. Rabinowitz J. M. F. dos Santos L. A. Schaller H. Schneuwly W. Schott D. Taqqu J. F. C. A. Veloso 《Hyperfine Interactions》2001,138(1-4):55-60
A measurement of the 2S Lamb shift in muonic hydrogen (μ−p) is being prepared at the Paul Scherrer Institute (PSI). The goal of the experiment is to measure the energy difference
ΔE(25
P
3/2−23
S
1/2) by laser spectroscopy (λ≈6μm) to a precision of 30 ppm and to deduce the root mean square (rms) proton charge radius with
10−3 relative accuracy, 20 times more precise than presently known.
An important prerequisite to this experiment is the availability of long-lived μp2S
-atoms. A 2S-lifetime of ∼1 μs – sufficiently long to perform the laser experiment – at H2 gas pressures of 1–2 hPa was deduced from recent measurements of the collisional 2S-quenching rate. A new low-energy negative muon beam yields an order of magnitude more muon stops in a small low-density gas
volume than a conventional cloud muon beam. A stack of ultra-thin carbon foils is the key element of a fast detector for keV-muons.
The development of a 2 keV X-ray detector and a 3-stage laser system providing 0.5 mJ laser pulses at 6 μm is on the way.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
20.
V. M. Orlovsky V. S. Skakun V. F. Tarasenko A. V. Fedenev 《Russian Physics Journal》2000,43(5):372-382
This paper presents the results of investigations of lasing by electronic transitions of xenon, krypton, and neon atoms, cadmium
and zinc ions, and nitrogen molecules and by oscillatory transitions of HF molecules. The processes responsible for the efficiency
of each of the lasers have been studied. The maximum radiation energies achieved are as follows: up to 200 J at λ∼2.8 μm for
a mixture of H2−SF6, up to 100 J at λ-1.73 μm and up to 50 J at λ=2.03 μm for xenon, up to 3 J at λ=358 nm for a mixture of Ar−N2, and up to 0.5 J at λ=585.5 nm for neon.
Institute of High-Current Electronics, Siberian Division of the Russian Academy of Sciences. Translated from Izvestiya Vysshikh
Uchebnykh Zavedenii, Fizika, No. 5, pp. 34–44, April, 2000. 相似文献