共查询到20条相似文献,搜索用时 750 毫秒
1.
T. Pérez-Ruiz C. Martínez Lozano V. Tomás J. Carpena 《Analytical and bioanalytical chemistry》1998,361(5):492-495
The interaction of diflunisal and naproxen with several surfactants was studied. Spectrofluorimetric methods were developed for the determination of both drugs in sodium dodecylsulfate micellar medium. The mixture of these drugs was resolved by synchronous fluorescence spectrometry using two scans. At Δλ = 20 nm, only naproxen yields a detectable signal that is unaffected by the presence of diflunisal. At Δλ = 110 nm the signal of diflunisal is not influenced by the presence of an up to 3-fold excess of naproxen. Mixtures containing naproxen/ diflunisal in ratios from 50:1 to 1:50 were analyzed with good results. The linear calibration ranges of both drugs were ca 0.02–2.0 μg mL–1. The method has satisfactorily been applied to a mixture of both drugs in serum. 相似文献
2.
Spectrofluorometric determination of hesperidin by manual and flow-injection methods 总被引:1,自引:0,他引:1
T. Pérez-Ruíz C. Martínez-Lozano V. Tomás J. Fenoll 《Fresenius' Journal of Analytical Chemistry》1999,364(3):279-283
A reliable and highly sensitive method for the determination of hesperidin is described. It involves the formation of a highly
fluorescent complex between hesperidin and aluminium (III) in a micellar medium. There is a linear relationship between fluorescence
intensity (λem = 496 nm, λex = 391 nm) and hesperidin concentration over the range 5 × 10–7– 2 × 10–5 mol L–1. The detection limit is 79 μg L–1. The method can easily be adapted to a flow system using a three-channel manifold, the peak height being proportional to
the hesperidin concentration over the range 1 × 10–6– 1 × 10–4 mol L–1. Manual and flow-injection procedures have been successfully applied to the determination of hesperidin in orange peel and
orange juice.
Received: 21 October 1998 / Revised: 16 December 1998 / Accepted: 25 December 1998 相似文献
3.
A. Ruiz Medina M. L. Fernández de Córdova A. Molina Díaz 《Analytical and bioanalytical chemistry》1999,365(7):619-624
A new, sensitive and very simple spectrofluorimetric biparameter sensor is described for the determination of salicylamide
and/or salicylic acid in pharmaceutical preparations. The method integrates the transitory retention and fluorescence detection
of both compounds on Sephadex QAE A-25 resin packed into a conventional flow-through cell. A monochannel manifold with two
alternative carriers is used. At pH 2.0 (first carrier) salicylic acid is selectively retained on the solid support and after
developing the analytical signal it is desorbed. At pH 11.0 (second carrier) both salicylic acid and salicylamide are simultaneously
and transitorily retained on the solid, the analytical signal now corresponding to both analytes. The monochromators were
tuned at 260 (excitation) and 415 (emission) nm, respectively. The calibration graph for salicylamide is linear over the range
0.01 to 0.32 μg mL–1 and for salicylic acid from 0.04 to 1.0 μg mL–1 in the presence of each other. The relative standard deviation and the sampling frequency for the determination of salicylamide
(0.20 μg mL–1) and salicylic acid (0.50 μg mL–1) were 1.1% and 35 h–1, and 0.9% and 45 h–1, respectively. Good results on application to individual determination or mixture resolution in pharmaceutical samples testify
to the usefulness of the proposed sensor.
Received: 20 April 1999 / Revised: 7 June 1999 / Accepted: 12 June 1999 相似文献
4.
Michael Winklmair Andreas J. Schuetz M. G. Weller Reinhard Niessner 《Fresenius' Journal of Analytical Chemistry》1999,363(7):619-624
A new, sensitive and very simple spectrofluorimetric biparameter sensor is described for the determination of salicylamide
and/or salicylic acid in pharmaceutical preparations. The method integrates the transitory retention and fluorescence detection
of both compounds on Sephadex QAE A-25 resin packed into a conventional flow-through cell. A monochannel manifold with two
alternative carriers is used. At pH 2.0 (first carrier) salicylic acid is selectively retained on the solid support and after
developing the analytical signal it is desorbed. At pH 11.0 (second carrier) both salicylic acid and salicylamide are simultaneously
and transitorily retained on the solid, the analytical signal now corresponding to both analytes. The monochromators were
tuned at 260 (excitation) and 415 (emission) nm, respectively. The calibration graph for salicylamide is linear over the range
0.01 to 0.32 μg mL–1 and for salicylic acid from 0.04 to 1.0 μg mL–1 in the presence of each other. The relative standard deviation and the sampling frequency for the determination of salicylamide
(0.20 μg mL–1) and salicylic acid (0.50 μg mL–1) were 1.1% and 35 h–1, and 0.9% and 45 h–1, respectively. Good results on application to individual determination or mixture resolution in pharmaceutical samples testify
to the usefulness of the proposed sensor.
Received: 20 April 1999 / Revised: 7 June 1999 / Accepted: 12 June 1999 相似文献
5.
M. R. Sovizi 《Journal of Thermal Analysis and Calorimetry》2010,102(1):285-289
Data on the thermal stability of drugs was required to obtain information for handling, storage, shelf life and usage. In
this study, the thermal stability of two nonsteroidal anti-inflammatory drugs (NSAIDs) was determined by differential scanning
calorimetry (DSC) and simultaneous thermogravimetery/differential thermal analysis (TG/DTA) techniques. The results of TG
analysis revealed that the main thermal degradation for the naproxen and celecoxib occurs in the temperature ranges of 196–300
and 245–359 °C, respectively. The TG/DTA analysis of compounds indicates that naproxen melts (at about 158.1 °C) before it
decomposes. However, the thermal decomposition of the celecoxib started about 185 °C after its melting. The influence of the
heating rate (5, 10, 15, and 20 °C min−1) on the DSC behavior of the both drug samples was verified. The results showed that, as the heating rate was increased, decomposition
temperatures of the compounds were increased. Also, the kinetic parameters such as activation energy and frequency factor
for the compounds were obtained from the DSC data by non-isothermal methods proposed by ASTM E696 and Ozawa. Based on the
values of activation energy obtained by various methods, the following order for the thermal stability was noticed: naproxen
> celecoxib. Finally, the values of ΔS
#, ΔH
#, and ΔG
# of their decomposition reaction were calculated. 相似文献
6.
A method has been developed to separate hydroxylated metabolites of the carcinogenic polycyclic aromatic hydrocarbon benzo[a]pyrene,
i. e. trans-4,5-, 7,8-, 9,10-dihydrodiol and 1-, 3-, 7-, and 9-phenol, by HPLC with amperometric detection employing an isocratic
methanol/water eluent (70:30, v/v) containing 0.5 g/L sulfuric acid and 1 g/L lithium perchlorate. Compared with the usually
applied fluorescence (λex = 265 nm, λem = 460 nm) and ultraviolet (λ = 265 nm) detection, the amperometric technique is about 2–12 times more sensitive for the determination
of all metabolites investigated. The method was applied to the determination of the seven metabolites of benzo[a]pyrene in
different water samples and in urine after solid-phase extraction (SPE). The results obtained by HPLC with amperometric detection
after SPE enrichment from an aqueous extract of a soil sample and from the urine of a rat intragastrically treated with benzo[a]pyrene
agreed well with the values determined with fluorescence and/or UV detection.
Received: 20 December 1996 / Revised: 10 March 1997 / Accepted: 30 April 1997 相似文献
7.
Mehmet Gokhan Caglayan Ismail Murat Palabiyik Mustafa Bor Feyyaz Onur 《Chemical Papers》2011,65(6):754-760
Simultaneous determination of enalapril maleate (ENA) and nitrendipine (NIT) in pharmaceutical preparations was performed
using liquid chromatography (LC) and the partial least-squares-1 (PLS-1) method. In LC, the separation was achieved on a C8
column and the optimum mobile phase for good separation in a gradient elution programme was found to be acetonitrile-water
(φ
r = 81: 19) and optimum flow-rate, temperature, injection volume, and detection wavelength were set at 1.0 mL min−1, 25°C, 10 μL, and 210 nm, respectively. Dienogest was selected as an internal standard. In the spectrophotometry, a PLS-1
chemometric method was used. The absorbance data matrix related to the concentration data matrix was established by measurement
of absorbances in their zero order spectra with an increment of Δλ = 1 nm in the 220–290 nm range for ENA and with Δλ = 1 nm in the 230–290 nm range for NIT in the PLS-1 method. Following this step, calibration was established by using this
data matrix to predict the unknown concentrations of ENA and NIT in their binary mixture. These optimised methods were validated
and successfully applied to a pharmaceutical preparation in tablet form and the results were subjected to comparison. 相似文献
8.
Rapid simultaneous determination of four anthracene derivatives using a single non-linear variable-angle synchronous fluorescence spectrum 总被引:1,自引:0,他引:1
A rapid, simple and inexpensive spectrofluorimetric method has been developed for the simultaneous identification and quantification
of anthracene (ANT), 9,10-dimethylanthracene (DIM), 2-aminoanthracene (AMI) and dibenz[ah]anthracene (DIB). A well-resolved spectrum for the mixture of these four compounds is obtained based on a single non-linear
variable-angle synchronous scanning. The linear concentration ranges are 10–1000, 5–500, 50–1000 and 10–200 ng mL–1 for ANT, DIM, AMI and DIB, respectively, at λex/λem = 358/380, 399/408, 414/465 and 298/394 nm, respectively. The analyses are performed in cyclohexane. Recoveries of 90.0–111.0%
in synthetic mixtures are obtained. The detection limits are 2.0 ng mL–1 for DIM, 2.7 ng mL–1 for ANT, 15.8 ng mL–1 for AMI and 4.2 ng mL–1 for DIB. The method has also been applied to several real water samples with satisfactory results.
Received: 29 March 2000 / Revised: 30 June 2000 / Accepted: 4 July 2000 相似文献
9.
T. J. López y López-Leytón M. A. Lage Yusty M. E. Alvarez Pi?eiro 《Fresenius' Journal of Analytical Chemistry》1998,362(3):341-343
Constant-wavelength synchronous spectrofluorimetry was used for the analysis of riboflavin in anchovies. Synchronous fluorescence
spectra were recorded between 300 and 600 nm at a scan rate of 240 nm min–1 and with excitation and emission slit-widths both set to 5 nm. The excitation-emission wavelength difference was 65 nm. The
fluorescence was measured by peak-area base between 430–509 nm. Recovery was higher than 90.8%.
Received: 22 December 1997 / Revised: 25 February 1998 / Accepted: 25 March 1998 相似文献
10.
A new, simple, selective and sensitive method for the spectrophotometric determination of antimony in rain water is described.
It includes preconcentrating Sb with surfactants (i.e. cetylpyridinium chloride (CPC) and Triton X-100 (TX-100)) into toluene
and allowing the extract to react with a dye, i.e. brilliant green (BG). The value of apparent molar absorptivity is 5.55
× 105 L-mol–1· cm–1 at λmax = 620 nm; the detection limit is 3 ng/mL Sb in rain water at 3-fold preconcentration.
Received: 6 June 1997 / Revised: 1 August 1997 / Accepted: 5 August 1997 相似文献
11.
A simple, rapid, selective, sensitive and economical method has been developed for the simultaneous determination of trace
amounts of palladium and nickel in aqueous methanolic medium using 2-(2-thiazolylazo)-5-dimethylam inobenzoic acid as an analytical
reagent by first derivative spectrophotometr y. Palladium is determined by measuring base to peak distance at λ=695.0 nm while
nickel is estimated by zero crossing method in the mixture. The linearity is maintained between 0.12–1.75 μg mL−1 for palladium and 0.07–1.60 μg mL−1 for nickel in the pH range 2.8–7.2 and 3.4–8.8 respectively. Seven replicate determinations of 1.0 μ g mL−1 of palladium and 0.8 μg mL−1 of nickel in a mixture give a mean signal height of 0.391 for Pd and 0.541 for Ni with relative standard deviations of 0.9%
and 1.2%, respectively. The sensitivity of the proposed method is 0.391 (dA/dλ)/(μg mL−1) for palladium and 0.685 (dA/dλ)/(μg mL−1) for nickel. Various parameters have been optimised for the simultaneous determination of palladium and nickel in various
complex samples.
Received March 30, 1999. Revision November 25, 1999. 相似文献
12.
A novel ruthenium(II) porphyrin complex, [Ru(phen)2MPyTPP] (phen = phenanthroline, MPyTPP = mono-(3′-Pyridine)-10,15,20-triphenyl porphyrin), has been prepared and characterized by elemental analysis, ESI-MS and NMR methods.
The interaction of the complex with G-quadruplex DNA has been studied by spectroscopy, and the results have shown that [Ru(phen)2MPyTPP] can bind to G-quadruplex d(TTAGGG)4 with high affinity. In the presence of d(TTAGGG)4, the characteristic Soret and intra-ligand (IL) transitions in the UV–Vis spectrum of the complex exhibit hypochromism of
25% (Δλ = 6 nm) and 18% (Δλ = 1 nm), respectively. The intrinsic binding constant was calculated according to the decay of
the Soret band as 3.02(±0.08) × 106 M−1. The positive signal of d(TTAGGG)4 in its circular dichroism spectra was clearly decreased in the presence of the complex, indicating the conformation of the
G-quadruplex was severely disturbed by the ruthenium(II) complex.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
13.
S. Z. Qureshi M. I. H. Helaleh N. Rahman R. M. A. Q. Jamhour 《Analytical and bioanalytical chemistry》1997,357(7):1005-1007
A spectrophotometric determination of trimethoprim is described based on the reaction of its amine group with persulfate
which acts as a strong oxidizing agent in alkaline media. The reaction produces a stable yellow colored compound after heating
in a boiling water bath for 30 min. At λmax 355 nm, Beer’s law is obeyed in the concentration range 10–60 μg ml–1 with a molar absorptivity of 2.7 × 103 l mol–1cm–1. The method is applied to formulations with sulfamethoxazole.
Received: 30 July 1996 / Revised: 16 October 1996 / Accepted: 22 October 1996 相似文献
14.
E. P. Surovoi S. V. Bin N. V. Borisova 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2010,84(8):1401-1405
During the irradiation of WO3 films d = 7–160 nm thick by light at λ = 320 nm (I = (1.5–7) × 1015 quantum cm−2 s−1), absorption band at λ = 850 nm appeared along with absorption band edge shift to shorter waves. The subsequent irradiation
of samples at λ = 850 nm caused the disappearance of the longwave absorption band. The intrinsic absorption edge of WO3 films was determined (λ = 320 nm). The degree of transformations of WO3 films increased under atmospheric conditions as the intensity of incident light and the time of irradiation (1–140 min) grew
and as film thickness decreased. A mechanism of photochemical transformations of WO3 films was suggested. This mechanism included the generation of electron-hole pairs, the recombination of part of nonequilibrium
charge carriers, the formation of [eVa2+e] centers, and the isolation of photolysis products. 相似文献
15.
B. Korchowiec M. Puggelli G. Gabrielli M. Nocentini C. Focardi 《Colloid and polymer science》1997,275(9):860-868
The behavior of the single spreading monolayers of β-lacto-globulin (β-LG) and dioleyl-phosphatidylcholine (DOPC), as well
as their mixtures, has been studied on subphases containing Na+ or Ca++ ions. The results show an influence of temperature and subphase on the studied systems. The behavior of the areas as a function
of the weight fraction of the two components shows significative and prevalently positive deviations from the additivity and
their bidimensional miscibility. The variation of ΔG
ex, ΔH
ex and ΔS
ex calculated for the DOPC–β-LG mixture having maximum deviation on two different supports allows to deduce that the interactions
are prevalently repulsive.
FTIR–ATR spectra of transferred plurilayers show that DOPC has a surface orientation which can originate the miscibility between
the protein and DOPC.
Received: 3 February 1997 Accepted: 3 June 1997 相似文献
16.
Ewa Bobrowska-Grzesik 《Mikrochimica acta》2001,136(1-2):31-34
Derivative spectrophotometry was applied for the simultaneous determination of amoxycillin and clavulanic acid in pharmaceutical
preparations: “Augmentin” inj. and tablets and “Amoksiklav” drops and tablets, in solutions after hydrolysis with sodium hydroxide.
As the absorption spectra overlap strongly (amoxycillin λmax = 247 nm and 290 nm, clavulanic acid λmax = 258 nm) the first and the second derivative spectrophotometric procedure was elaborated for their determination. Amoxycillin
was determined at λ = 257.9 nm (1-st derivative spectra) or λ = 273 nm (2-nd derivative) while clavulanic acid at λ = 280.3 nm
(1-st derivative) or λ = 285 nm (2-nd derivative spectra). The Beer’s law is obeyed in the range of 0.004–0.04 mg/ml for amoxycillin
and 0.002–0.02 mg/ml for clavulanic acid.
Received December 6, 1999. Revision August 1, 2000. 相似文献
17.
Thermogravimetric characteristics and kinetic of co-pyrolysis of olive residue with high density polyethylene 总被引:1,自引:1,他引:0
A. Aboulkas K. El Harfi M. Nadifiyine A. El Bouadili 《Journal of Thermal Analysis and Calorimetry》2008,91(3):737-743
The co-pyrolytic behaviour of olive residue/high-desity polyethylene mixture was examined with a thermogravimetric analyser.
The experiments were done over the temperature range of room temperature to 1273 K at various heating rates (2, 10, 20 and
50 K min−1) and in a nitrogen atmosphere.
The results indicated that mass loss process of mixture consists of three distinct stages and the increase of the heating
rate shifts in the maximum rate loss to higher temperature. The difference of mass loss (Δm) between experimental and theoretical, calculated as algebraic sums of the mixture for different heating rates of 2, 10,
20 and 50 K min−1, is about 7–11% at 740–900 K. These experimental results indicate a significant synergistic effect during co-pyrolysis of
olive residue with high-density polyethylene. In addition, a kinetic analysis was performed to fit thermogravimetric data,
the mixture is considered as multi-stage process. A reasonable fit to the experimental data was obtained for all materials
and their mixture by isoconversional Friedman method. 相似文献
18.
Surface tension measure-ments in aqueous cetyltrimethyl ammonium bromide were performed in presence of various amounts of
9-(hydroxymethyl)anthracene (AM), 9-[1-(1-hydroxy)ethyl]anthracene (THAE), and 9-[1-(1-hydroxy-2,2,2-trifluoro)ethyl]anthracene
(TFAE). Free energies ΔG
⊖
m and ΔG
⊖
i of micellization and of adsorption to the air–water interface, respectively, were determined as well as the corresponding
enthalpies and entropies. ΔG
o−
m of micellization increased in the presence of AM and THAE, but became more negative when TFAE was added. In contrast to AM
and THAE, TFAE addition decreases ΔS
⊖
i. For this peculiarity of TFAE, its location and orientation in micellar solution was investigated by means of UV and 19F-NMR spectroscopy.
Received: 26 March 1997 Accepted: 16 May 1997 相似文献
19.
J. Kunze M. A. Wimmer S. Koelling E. Schneider 《Fresenius' Journal of Analytical Chemistry》1998,361(5):496-499
A ‘one bottle’ method to determine particulate debris of titanium and zirconium in blood serum was developed. Inductively
coupled plasma – optical emission spectrometry (ICP-OES) was used to simultaneously detect both elements at concentrations
above 50 ng/mL. Pressurized digestion by means of nitric and hydrofluoric acid in PTFETM-containers in a specific time-heat-pressure protocol apparatus was applied to assure complete solvation of particles including
oxides. Total decomposition of the matrix was achieved and reasonable detection limits were accomplished. The amount of remaining
carbon did not cause any matrix problems during measurement.
Received: 10 October 1997 / Revised: 5 December 1997 / Accepted: 9 December 1997 相似文献
20.
Nai-Xing Wang Lei Wang Wei Jiang Yue-Zhen Ren Zhi-Kun Si Xun-Xing Qiu Gao-Ying Du Ping Qi 《Analytical and bioanalytical chemistry》1998,361(8):821-824
Norfloxacin (NFX) is proposed as reagent for the derivative spectrophotometric determination of neodymium, holmium and erbium
in mixed rare earths. The absorption spectra of 4f electron transitions of the systems of neodymium, holmium and erbium complexes
with norfloxacin in presence of cetylpyridinium chloride were studied by normal and derivative spectra. The absorption bands
found normally at 575 nm for neodymium, 450 nm for holmium and 523 nm for erbium were enhanced markedly. Using the second
derivative spectrum, Beer’s Law is obeyed from 5.0 × 10–5∼ 2.5 × 10–4 mol dm–3 for neodymium, holmium and erbium. The relative standard deviations are 1.0, 1.4 and 1.1% for 6.9 × 10–5 mol dm–3 of neodymium, 6.1 × 10–5 mol dm–3 of holmium and 6.0 × 10–5 mol dm–3 of erbium, respectively. A method for the direct determination of neodymium, holmium and erbium in mixtures of rare earth
elements with good accuracy and selectivity, is described.
Received: 18 December 1997 / Revised: 23 February 1998 / Accepted: 26 February 1998 相似文献