共查询到20条相似文献,搜索用时 15 毫秒
1.
Mandrioli R Mercolini L Ferranti A Furlanetto S Boncompagni G Raggi MA 《Analytica chimica acta》2007,591(2):141-147
A high-performance liquid chromatographic method has been developed for the determination in human plasma of the specific serotonin reuptake inhibitor (SSRI) antidepressant paroxetine and its three main metabolites (M1, M2, M3). Fluorescence detection was used, exciting at λ = 294 nm and monitoring emission at λ = 330 nm for paroxetine (λexc = 280 nm, λem = 330 nm for M1 and M2; λexc = 268 nm, λem = 290 nm for M3). Separation was obtained on a reversed-phase C18 column using a mobile phase composed of 66.7% aqueous phosphate at pH 2.5 and 33.3% acetonitrile. Imipramine (λexc = 252 nm, λem = 390 nm) was used as the internal standard. A careful pre-treatment of plasma samples was developed, using solid-phase extraction with C8 cartridges (50 mg, 1 mL). The calibration curves were linear over a working range of 2.5-100 ng mL−1 for paroxetine and of 5-100 ng mL−1 for all metabolites. The limit of detection (LOD) was 1.2 ng mL−1 for PRX and 2.0 ng mL−1 for the metabolites. The method was applied with success to plasma samples from depressed patients undergoing treatment with paroxetine. Hence, the method seems to be suitable for the therapeutic drug monitoring of paroxetine and its main metabolites in depressed patients’ plasma. 相似文献
2.
Fluorescence and terbium-sensitised luminescence properties of new quinolone garenoxacin have been studied. The fluorimetric method allows the determination of 0.060-0.600 μg ml−1 of garenoxacin in aqueous solution containing HCl/KCl buffer (pH 1.5) with λexc=282 nm and λem=421 nm. Micellar-enhanced fluorescence was also studied, leading to a higher than 400% increase in analytical signal in presence of 12 mM sodium dodecyl sulphate (SDS), allowing the determination of 0.020-0.750 μg ml−1 of garenoxacin. The terbium-sensitised luminescence method allows the determination of 0.100-1.500 μg ml−1 of garenoxacin in 12 mM SDS solution containing 0.08 M acetic acid/sodium acetate buffer (pH 4.1) and 7.5 mM Na2SO3 (chemical deoxygenation agent), with λexc=281 nm and λem=546 nm. Relative standard deviation (R.S.D.) values for the three methods were in the range 1.0-2.0%. The proposed procedures have been applied to the determination of garenoxacin in spiked human urine and serum. 相似文献
3.
The present work describes the development of a fast and robust sequential injection fluorimetric procedure for the determination of Sn in juices of canned fruits. The developed automatic methodology is based on the complexation of Sn with 8-hydroxyquinoline-5-sulfonic acid (HQSA) to form a fluorimetric product (λexc = 354 nm; λem = 510 nm). The influence of dimethylsulfoxide (DMSO) and cetylpyridinium bromide (CPB) on the sensitivity of the fluorimetric determination was evaluated.Linear calibration plots were obtained for Sn concentrations between 1 and 10 mg L−1, with a detection limit of 0.38 mg L−1. In each analytical cycle 0.006 mg of HQSA and 0.47 mg of CPB were consumed and 1.5 mL of effluent was generated.The developed methodology was applied to the determination of Sn in juices of canned fruits and the results complied with those furnished by an electrothermal atomic absorption spectrometry comparison procedure, with relative deviations lower than 5.2%.The automatic procedure exhibited good precision (R.S.D. < 1.4%) and the sampling rate was about 70 determinations per hour. 相似文献
4.
Paraskevas D. Tzanavaras Eftichios A. Kalaitzantonakis Anastasios N. Voulgaropoulos 《Analytica chimica acta》2005,547(1):98-103
A normal spectrophotometric and a stopped-flow (SF) spectrofluorimetric method have been developed and optimized for the determination of alendronic acid (ALD) in its pharmaceutical formulations. Both methods are automated using the sequential injection analysis (SIA) principle. The spectrophotometric assay is based on the reaction of the analyte with Cu(II) ions in acidic medium to form an UV-absorbing derivative (λmax = 240 nm). The SF spectrofluorimetric method is based on the reaction of ALD with o-phthalaldehyde (OPA) in the presence of 2-mercaptoethanol at basic medium (λex = 340 nm/λem = 455 nm). Linear calibration curves were obtained in the range 1.0-60.0 mg l−1 ALD for the UV method, and in the range 0.13-10.0 mg l−1 ALD for the SF spectrofluorimetric one. The sampling rates were 60 and 30 h−1, respectively. The developed assays are critically compared and their advantages are discussed. Both methods were applied to the analysis of an ALD containing pharmaceutical formulation with satisfactory accuracy and precision. 相似文献
5.
Synchronous-scan fluorescence spectra of dodecylbenzene sulfonic acid sodium salt (SDBS) and pyrene in aqueous solution were studied. The concentration ranges of SDBS and pyrene in aqueous solutions were 0.01-10.00 and 0.001-0.050 mg L−1, respectively. The optimized wavelength differences (Δλ) of 46-55 and 38 nm were maintained between excitation and emission wavelengths for SDBS and pyrene, respectively, and they were found to be suitable for effective determination of SDBS and pyrene without mutual interferences; the peaks were observed at λex 229-232 nm (SDBS) and λex 335 nm (pyrene). Linear relationships between synchronous-scan fluorescence spectroscopy (SFS) intensity and concentration of SDBS or pyrene in aqueous solution (Milli-Q water, river water, and mucus of fish gills) were established. It was demonstrated that SFS method was effective for simultaneous analyses of SDBS and pyrene in mixed solution. 相似文献
6.
Horst Kunkely 《Journal of organometallic chemistry》2004,689(18):2940-2943
The electronic spectra of solid MgCp2 (Cp = cyclopentadienyl) show features which indicate the presence of intramolecular interligand interactions. The fluorescence of MgCp2 (λmax = 363 nm) undergoes a considerable Stokes shift which is apparently caused by a bonding attraction between both Cp rings in the excited state. An additional phosphorescence of the (Cp−)2 fragment (λmax = 535 nm) appears at 77 K. 相似文献
7.
A photochemical study of allyl iron complexes of the type, (η3-2-R-C3H4)Fe(CO)(NO)(X) (R = H or Cl; X = CO or PPh3) is presented. These compounds were studied in solid matrixes at 20 K, and at room temperature, by a combination of laser flash at 355 nm and steady-state photolysis. The predominant photochemical process for these compounds is loss of a CO ligand. In addition, exhaustive irradiation of (η3-2-R-C3H4)Fe(CO)(NO)(PPh3) with λexc > 300 nm provided evidence for a haptotropic shift of the allyl group from η3 to η1 coordination. 相似文献
8.
Demetrius G. Themelis 《Analytica chimica acta》2002,452(2):295-302
This study reports a sensitive solvent extraction flow-injection (FI) method for the simultaneous spectrophotometric determination of free cyanide and thiocyanate in human saliva and pralidoxime solutions. Cyanide and thiocyanate form colored (λmax=540 nm) ternary complexes with copper and 2,2′-dipyridyl-2-quinolylhydrazone (DPQH) that are extractable into chloroform. The determination of thiocyanates in the presence of cyanides is accomplished after on-line masking of the latter with formaldehyde through a binary inlet static mixer (BISM). Total thiocyanates and cyanides are determined in a second run, without the use of the masking agent. The proposed method allows the determination of the analytes in the range of 0-4 mg l−1 thiocyanates and 0-3 mg l−1 cyanides, with the 3σ detection limits being 0.007 and 0.004 mg l−1, respectively. The precision of the method (sr<1.0% at 1 mg l−1 CN− or SCN−, n=12 in both cases) and the sampling rates were quite satisfactory (60 injections per hour). The method was applied to the analysis of human saliva and pralidoxime solutions and gave recoveries in the range of 98.0-102.2% for both analytes whereas the mean relative error was er=1.7%. 相似文献
9.
Fotini S. Kika 《Talanta》2007,71(3):1405-1410
The present work reports the first sequential injection (SI) method for the spectrophotometric determination of Ti(IV). The method is based upon the reaction of Ti(IV) with chromotropic acid (CA) in acidic medium to form a water-soluble complex (λmax = 420 nm). The chemical and instrumental variables of the system that affected the reaction were studied. Selectivity was greatly enhanced using ascorbic acid. A linear calibration graph was obtained in the range 0.2-10.0 mg l−1 Ti(IV) at a sampling frequency of 24 h−1. The precision was satisfactory (sr = 1.5% at 5.0 mg l−1 Ti(IV), n = 12) and the 3σ limit of detection, cL, was 0.7 mg l−1 (n = 10). The developed method proved to be adequately selective and was applied successfully to the analysis of real samples (dental implant and natural Moroccan phosphate rock) giving accurate results based on recovery studies (98-105%). 相似文献
10.
No previous publications about percutaneous absorption of polyethylene glycol 25 p-aminobenzoic acid (PEG-25 PABA) have been found in the literature and the expected levels to be found in human urine after sunscreens use are unknown. The method proposed here is suitable to determine PEG-25 PABA in the urine of sunscreens users in order to carry out studies on body accumulation/excretion. It is based on solid-phase extraction (SPE) with size-exclusion liquid chromatography determination. Solid-phase extraction allows the analyte to be retained and subsequently eluted for a clean-up, using a silica-based cartridge. The size-exclusion liquid chromatography of the eluted allows the rest of matrix interferences to be avoided. Fluorescence intensity was measured at λem = 350 nm (λexc = 300 nm). The sensitivity of the proposed method is in the order of 450 ± 5 mL ng−1 and the detection limit (3 Sy/x/b) in the measured solutions is in the order of 13 ng mL−1, that is 2.6 ng mL−1 in urine samples. The method enables PEG-25 PABA to be determined in both, spiked and unspiked human urine samples. Results obtained for spiked human urine samples (11-100 ng mL−1) demonstrated the accuracy of the method. The mean relative standard deviation of the results was in the order of 3-10%. Three volunteers applied a sunscreen lotion containing a 8% PEG-25 PABA sunscreen cream and their urinary excretion was controlled from the moment of application until the excreted amounts were no longer detectable. 相似文献
11.
According to the current demands of environmentally friendly analytical chemistry and with a view to achieving lower reagent consumption with improved analytical performance, an automatic methodology composed of a photoreactor and fluorimetric detection (λexc = 287 nm, λem = 378 nm) was developed. To this end, a sequential injection analysis (SIA) system was developed for indomethacin determination using ultra-violet (UV) light which promotes an increase in the fluorescence of indomethacin. This increase in sensitivity makes it possible to apply this methodology to a dissolution test and to determine indomethacin in pharmaceutical formulations.The calibration graph for indomethacin was linear between 4.10 × 10−6 and 9.00 × 10−5 mol L−1and the detection limit was 1.23 × 10−6 mol L−1. The method was proven to be reproducible with a R.S.D. < 5% and sampling rate of approximately 20 per hour. The potential effect of several compounds commonly used as excipients on analytical signals was studied and no interfering effect was observed. Statistical evaluation at the 95% confidence level showed good agreement between the results obtained for the pharmaceutical samples with both the SIA system and comparison batch procedures. 相似文献
12.
Two accurate, reliable, and highly sensitive spectrofluorimetric methods were developed for simultaneous determination of binary mixture gemfibrozil and rosiglitazone in human plasma without prior separation steps. The first method is based on synchronous fluorescence spectrometry using double scans. At Δλ = 27 nm, gemfibrozil yields detectable signal that is independent of the presence of rosiglitazone. Similarly, at Δλ = 120 nm the signal of rosiglitazone is not influenced by the presence of gemfibrozil. Signals at two wavelengths, 301 (Δλ = 27 nm) and 368 nm (Δλ = 120 nm) vary linearly with gemfibrozil and rosiglitazone concentrations over the range 100-700 ng mL−1 (for gemfibrozil) and 20-140 ng mL−1 (for rosiglitazone), respectively. The limits of detection (LOD) were 2.3 and 2.72 ng mL−1 for gemfibrozil and rosiglitazone, respectively. The second method is based on the technique of simultaneous equations (Vierodt's method), in which 258 nm was selected as the excitation wavelength. Two equations are constructed based on the fact that at (λEm2=302 nm of gemfibrozil) and (λEm2=369 nm of rosiglitazone) the fluorescence of the mixture is the sum of the individual fluorescence of gemfibrozil and rosiglitazone. The limits of detection (LOD) were 28.1 and 23.63 ng mL−1 for gemfibrozil and rosiglitazone, respectively. The proposed methods were successfully applied for the determination of the two compounds in synthetic mixtures and in human plasma with a good recovery. 相似文献
13.
Edwin Palacio-Barco 《Analytica chimica acta》2010,668(1):74-9100
In this paper, an on-line spectrofluorimetric system is proposed for a simple, rapid and accurate measurement of volatile fatty acids (VFA) in anaerobic treatment processes. The determination method is based on the derivatization of VFA with N-(1-naphthyl)ethylenediamine (EDAN) followed by a spectrofluorimetric detection of the corresponding amide. The analytical procedure is automated with a flow analysis technique, coupling multisyringe (MSFIA) and multi-pumping (MPFS) methods. Operative conditions have been investigated with a special attention paid to the activation and amidation steps and to the liquid-liquid extraction of the derivatized final product. Fluorescence intensities (λem = 335 nm, λex = 395 nm) were found to be proportional to the concentration of VFA, expressed as acetic equivalent, in the range 19-1000 mg L−1, with a detection limit (3σ) of 5.1 mg L−1. Our results showed a good selectivity for VFA as compared to other organic and inorganic compounds usually found in sewage sludges. Validation of the on-line system developed has been assessed by application of the procedure to aqueous samples originating from sewage sludge treatment plants. The results were in good agreement with ion chromatography measurements. 相似文献
14.
An artificial neural network (ANN) procedure was used in the development of a catalytic spectrophotometric method for the determination of Cu(II) and Ni(II) employing a stopped-flow injection system. The method is based on the catalytic action of these ions on the reduction of resazurin by sulfide. ANNs trained by back-propagation of errors allowed us to model the systems in a concentration range of 0.5-6 and 1-15 mg l−1 for Cu(II) and Ni(II), respectively, with a low relative error of prediction (REP) for each cation: REPCu(II) = 0.85% and REPNi(II) = 0.79%. The standard deviations of the repeatability (sr) and of the within-laboratory reproducibility (sw) were measured using standard solutions of Cu(II) and Ni(II) equal to 2.75 and 3.5 mg l−1, respectively: sr[Cu(II)] = 0.039 mg l−1, sr[Ni(II)] = 0.044 mg l−1, sw[Ni(II)] = 0.045 mg l−1 and sw[Ni(II)] = 0.050 mg l−1. The ANNs-kinetic method has been applied to the determination of Cu(II) and Ni(II) in electroplating solutions and provided satisfactory results as compared with flame atomic absorption spectrophotometry method. The effect of resazurin, NaOH and Na2S concentrations and the reaction temperature on the analytical sensitivity is discussed. 相似文献
15.
Alexandre Boulay Sophie Laine Nadine Leygue Eric Benoist Sophie Laurent Luce Vander Elst Robert N. Muller Béatrice Mestre-Voegtle Claude Picard 《Tetrahedron letters》2013
In the design of dual-imaging probes, the first functionalized and neutral heterobimetallic Re(I)–Gd(III) complex, highly soluble in aqueous solutions, has been prepared. This system exhibits interesting photophysical properties (λem = 578 nm, ? = 1.4%) for optical imaging and substantial higher relaxivity (r1 = 6.6 mM−1 s−1 at 0.47 T and 37 °C) than the clinically used MRI contrast agents. Moreover, this system incorporates an aromatic ester functionality suitable for bioconjugation. 相似文献
16.
Discrimination between virgin olive oils and pure olive oils is of primary importance for controlling adulterations. Here, we show the potential usefulness of two multiway methods, unfold principal component analysis (U-PCA) and parallel factor analysis (PARAFAC), for the exploratory analysis of the two types of oils. We applied both methods to the excitation-emission fluorescence matrices (EEM) of olive oils and then compared the results with the ones obtained by multivariate principal component analysis (PCA) based on a fluorescence spectrum recorded at only one excitation wavelength. For U-PCA and PARAFAC, the ranges studied were λex=300-400 nm, λem=400-695 nm and λex=300-400 nm, λem=400-600 nm. The first range contained chlorophylls, whose peak was much more intense than those of the rest of species. The second range did not contain the chlorophylls peak but only the fluorescence spectra of the remaining compounds (oxidation products and Vitamin E). The three-component PARAFAC model on the second range was found to be the most interpretable. With this model, we could distinguish well between the two groups of oils and we could find the underlying fluorescent spectra of three families of compounds. 相似文献
17.
M. Kusatsugu 《Journal of solid state chemistry》2008,181(5):1176-1183
Oxyfluoride glasses with a small amount of NiO are prepared using a conventional melt quenching technique, and the spatially selected crystallization of LaF3 and CaF2 crystals is induced on the glass surface by irradiations of continuous wave lasers with a wavelength of λ=1064 or 1080 nm. Dots and lines including LaF3 crystals are patterned by heat-assisted (300 °C) laser irradiations (λ=1064 nm) with a power of P=1 W and an irradiation time of 10 s for dots and a scanning speed of S=5 μm/s for lines. Lines consisting of CaF2 crystals are also patterned in an ErF3-doped oxyfluoride glass by laser irradiations (λ=1080 nm) with a power of P=1.7 W and a scanning speed of S=2 μm/s, and the incorporation of Er3+ ions into CaF2 crystals is confirmed from micro-photoluminescence spectrum measurements. It is proposed that the lines patterned by laser irradiations in this study are consisted of the composite of LaF3 or CaF2 nanocrystals and SiO2-based oxide glassy phase. It is demonstrated that a combination of Ni2+-dopings and laser irradiations is effective in spatially selected local crystallizations of fluorides in oxyfluoride glasses. 相似文献
18.
Paraskevas D. Tzanavaras 《Talanta》2009,77(5):1614-1050
A new automated spectrophotometric method for the determination of total sulfite in white and red wines is reported. The assay is based on the reaction of o-phthalaldehyde (OPA) and ammonium chloride with the analyte in basic medium under SI conditions. Upon on-line alkalization with NaOH, a blue product is formed having an absorption maximum at 630 nm. The parameters affecting the reaction - temperature, pH, ionic strength, amount concentration and volume of OPA, amount concentration of ammonium chloride, flow rate and reaction coil length - and the gas-diffusion process - sample and HCl volumes, length of mixing coil, donor flow rate - were studied. The proposed method was validated in terms of linearity (1-40 mg L−1, r = 0.9997), limit of detection (cL = 0.3 mg L−1) and quantitation (cQ = 1.0 mg L−1), precision (sr = 2.2% at 20 mg L−1 sulfite, n = 12) and selectivity. The applicability of the analytical procedure was evaluated by analyzing white and red wine samples, while the accuracy as expressed by recovery experiments ranged between 96% and 106%. 相似文献
19.
Flow-injection analysis system (FIA system), which was based on Fe(II)-catalyzed oxidation of chromotropic acid with hydrogen peroxide, was developed for the determination of hydrogen peroxide. The chromotropic acid has a fluorescence measured at λem = 440 nm (emission wavelength) with λex = 235 nm (excitation wavelength), and the fluorescence intensity at λem = 440 nm quietly decreased in the presence of hydrogen peroxide and Fe(II), which was caused by Fe(II)-catalyzed oxidation of chromotropic acid with hydrogen peroxide. By measuring the difference of fluorescence intensity, hydrogen peroxide (1.0 × 10−8-1.0 × 10−3 mol L−1) could be determined by the proposed FIA system, whose analytical throughput was 40 samples h−1. The relative standard deviation (RSD) was 1.03% (n = 10) for 4.0 × 10−8 mol L−1 hydrogen peroxide. The proposed FIA technique could be applied to the determination of hydrogen peroxide in rain water samples. 相似文献
20.
A sensitive and selective enzymatic kinetic method for the simultaneous determination of mixtures of carbaryl and phoxim pesticides was researched and developed. It was based on the inhibitory effect of the pesticides on acetylcholinesterase (AChE), and the use of 5,5′-dithiobis(2-nitrobenzoic) acid (DTNB) as a chromogenic reagent for the thiocholine iodide (TChI) released from the acetylthiocholine iodide (ATChI) substrate. The DTNB-thiocholine reaction was investigated by a spectrophotometric-kinetic approach. The complex rate equation for the formation of the chromogenic product, P, was solved under certain experimental conditions, which enabled the absorbance (AP, at λmax = 412 nm) from the mixtures of the two pesticide inhibitors to be directly related to their concentrations provided the absorbance additivity was followed. The spectra were measured for mixtures of carbaryl and phoxim at different concentrations, and at t = 904 s, T = 35 °C, pH = 7.5, cATChI = 0.14, and cAChE = 0.10 mg mL−1. The detection limits of the enzymatic kinetic spectrophotometric procedures for the determination of the carbaryl and phoxim were 4.7 and 0.59 μg L−1, respectively.Calibration models for chemometrics methods, such as principal component regression (PCR), partial least squares (PLS) and radial basis function-artificial neural network (RBF-ANN) were constructed and verified with synthetic samples of the mixtures of the two pesticides. The best performing model was based on the RBF-ANN method yielding at approximately 10 ppb analyte concentrations, %RPET (carbaryl = 5.2; phoxim = 6.5), %Recovery (approx.105%) and %RPET (6.5). Various spiked town-water samples produced recoveries in the range of 98.8-103% for each pesticide. 相似文献