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1.
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   

2.
A simple and sensitive chemiluminescence (CL) method coupled with flow-injection technique is proposed to determine naproxen (NAP). The method is based upon the enhancement of the weak CL signal arising from the reaction of Ce(IV) and Na2S2O4 with Eu3+ to form the Eu3+-Ce(IV)-Na2S2O4 system. The CL intensity was significantly increased by the introduction of NAP into this system in the presence of silver nanoparticles (Ag NPs). Examination of the recorded UV–vis spectra and fluorescence spectra indicated that the energy of the intermediate SO2*, which originated from the redox reaction of Ce(IV) and Na2S2O4, was transferred to Eu3+ via NAP and that the process was accelerated by Ag NPs due to their catalytic activity. Under the optimum conditions, the CL intensity was increased with increasing NAP concentration and the correlation was linear (r = 0.9992) over the NAP concentration range of 1–420 ng mL−1. The limit of detection (LOD) was 0.11 ng mL−1 with a relative standard deviation (RSD) of 1.15% for 5 replicate determinations of 200 ng mL−1 NAP. The method was successfully applied to determine NAP in pharmaceutical and biological samples.  相似文献   

3.
It is found that silver nanoparticles (AgNPs) can further enhance the fluorescence intensity of curcumin (CU) - cetyltrimethylammonium bromide (CTAB) – nucleic acids and improve its anti-photobleaching activity. Under optimum conditions, the enhanced fluorescence intensity is proportion to the concentration of nucleic acids in the range of 2.0 × 10−8–1.0 × 10−6 g mL−1 for fish sperm DNA (fsDNA), 2.0 × 10−8–1.0 × 10−6 g mL−1 for calf thymus DNA (ctDNA), 1.0 × 10−8–1.0 × 10−6 g mL−1 for yeast RNA (yRNA), and their detection limits (S/N = 3) are 8.0 ng mL−1, 10.5 ng mL−1 and 5.8 ng mL−1, respectively. This method is used for determining the concentration of DNA in actual sample with satisfactory results. The interaction mechanism is also studied.  相似文献   

4.
A new, simple and sensitive spectrofluorimetric method has been developed for the determination of oseltamivir phosphate (OSP) in capsules. The method is based on the reaction between oseltamivir and fluorescamine in borate buffer solution of pH 8.50 to give highly fluorescent derivatives that are measured at 483 nm using an excitation wavelength of 381. The different experimental parameters effecting the development and stability of the reaction product were carefully studied and optimized. The fluorescence intensity concentration plot is rectilinear over the range 50–450 ng mL−1 with a lower detection limit (LOD) of 1.219 ng mL−1 and limit of quantitation (LOQ) of 4.064 ng mL−1. Selectivity was validated by subjecting stock solution of OSP to acidic, basic, oxidative, and thermal degradation. No interference was observed from excipients present in formulations. The developed method was successfully applied to determination of the drug in capsules. The mean % recovery (n = 6) was 100.08. The results obtained were in good agreement with those obtained using a reported spectrophotometric method.  相似文献   

5.
Chemiluminescence (CL) of the reaction system tetracycline–H2O2–Fe(II)/(III)–Eu(III) was used for the determination of tetracycline hydrochloride in water, pharmaceutical preparations, and honey. The CL spectrum registered for this system shows emission bands typical of Eu(III) ions, with a maximum at λ ∼ 600 nm, corresponding to the electronic transitions of 5D07F1 and 5D07F2. A strong chemiluminescence intensity characteristic of europium(III) ions in the system tetracycline–H2O2–Fe(II)/(III)–Eu(III), as contrasted to the emission of the system tetracycline–H2O2–Fe(II)/(III) without Eu(III), proves that the Eu(III) ion plays the role of a chemiluminescence sensitizer, accompanying tetracycline oxidation in the Fenton system (H2O2–Fe(II)/(III)). A linear dependence was observed for the integrated CL light intensity on the tetracycline concentration in the range of 2 × 10−7 to 3 × 10−5 mol l−1 with the detection limit of 5 × 10−8 mol l−1 in aqueous solution.  相似文献   

6.
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   

7.
Single phase LiCo1 − y Ni y O2 (y = 0.4 and 0.5) with fine particles and high homogeneity was synthesized by “chimie douce” assisted by citric acid as the polymeric agent and investigated as positive electrodes in rechargeable lithium batteries. The long-range and short-range structural properties are investigated with experiments including X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and superconducting quantum interference device magnetometry. The physicochemical properties of the powders (crystallinity, lattice constants, grain size) have been investigated in this composition. The powders adopted the α-NaFeO2 structure as it appeared from XRD and FTIR results. Magnetic measurements shows signal at low temperature attributed to the magnetic domains in the nanostructure sample from which we estimated that the cation mixing are 3.35 and 4.74% for y = 0.4 and 0.5 in LiCo1 − y Ni y O2, respectively. LiCo0.5Ni0.5O2 cathode yields capacity (135 mAh g−1) compared to LiCo0.6Ni0.4O2 cathode (147 mAh g−1) when discharged to a cutoff voltage of 2.9 V vs. Li/Li+. Lower capacity loss and higher discharge efficiency percentage are observed for the cell of LiCo0.6Ni0.4O2 cathode.  相似文献   

8.
Nano-sized Al3+-doped V2O5 cathode materials, Al0.2V2O5.3−δ , were prepared by an oxalic acid assisted sol–gel method at 350 °C (sample A) and 400 °C (sample B). X-ray diffraction confirmed that samples A and B were pure phase Al0.2V2O5.3−δ with an orthorhombic structure close to that of V2O5. Scanning electron microscopy showed that sample A was in nanoscale with a mean particle size about 50 nm. Cyclic voltammetry showed the good electrochemical and structural reversibility of the Al0.2V2O5.3−δ nanoparticles during the Li+ insertion/extraction process. The Al0.2V2O5.3−δ nanoparticles exhibited excellent charge–discharge cycling performance and rate capability compared to that of bulky V2O5 electrodes. For instance, the materials delivered a reversible specific capacity about 180 mAh g−1 (sample A) and 150 mAh g−1 (sample B), in the potential window of 4.0–2.0 V at the current density of 150 mA g−1. The Al0.2V2O5.3−δ nanoparticles in particular showed almost no capacity fading for at least 50 cycles.  相似文献   

9.
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   

10.
Eu(III)-9-acridinecarboxylate (9-ACA) complex was synthesized and characterized by elemental analysis, conductivity measurement, IR spectroscopy, thermal analysis, mass spectroscopy, 1H-NMR, fluorescence and ultraviolet spectra. The results indicated that the composition of this complex is [Eu(III)-(9-ACA)2(NCS)(C2H5OH)2] 2.5 H2O and the oxygen of the carbonyl group coordinated to Eu(III). The interaction between the complex with nucleotides guanosine 5′- monophosphate (5′-GMP), adenosine 5′-diphosphates (5′-ADP), inosine (5′-IMP) and CT-DNA was studied by fluorescence spectroscopy. The fluorescence intensity of Eu(III)-9-acridinecarboxylate complex was enhanced with the addition of CT-DNA. The effect of pH values on the fluorescence intensity of Eu(III) complex was investigated. Under experimental conditions, the linear range was 9–50 ng mL−1 for calf thymus DNA (CT- DNA) and the corresponding detection limit was 5 ng mL−1. The results showed that Eu(III)-(9-ACA)2 complex binds to CT-DNA with stability constant of 2.41 × 104 M .  相似文献   

11.
A novel solid substrate-room temperature phosphorimetry (SS-RTP) was developed for determination of bumetanide (BMTN). It was validated by determining selectivity, linearity, accuracy, precision, and signal to noise ratio (S/N) for analysis. And all the experiments presented in this work were based on that BMTN inhibited the formation of [Fe-morin]3+ ([FeR]3+) complex by the reaction between Fe3+ and R, which led to severe quenching of room temperature phosphorescence (RTP) signal. The rate constant of the reaction (k) was 2.44 × 10−4 s−1, the activation energy (E) was 21.39 kJ mol−1. Detection limit of this method (LD, 5.0 ag spot−1, corresponding concentration was 1.2 × 10−14 g mL−1) was evaluated and compared with other methods, indicating better sensitivity for BMTN determination using this technique. And due to the high sensitivity of the method, it has been successfully applied to determine BMTN in human urine samples. The linear range was from 0.040 pg mL−1 to 4.0 pg mL−1, allowing wide determined range of BMTN. Meanwhile, the mechanism of this method was also discussed.  相似文献   

12.
Infrared (IR) and UV spectra of ternary Li2O–CuO–P2O5 glasses in two series Li2O(65−X)%–CuO(X%)–P2O5(35%), X = 20, 30, 40 and Li2O(55−X)%–CuO(X%)–P2O5(45%), X = (10, 20, 30) were studied. Infrared (IR) investigations showed the metaphosphate and pyrophosphate structures and with increase of CuO content in metaphosphate glass, the skeleton of metaphosphate chains is gradually broken into short phosphate groups such as pyrophosphate. IR spectra showed one band at about 1,220 and 1,260 cm−1 for P2O5(35%) and P2O5(45%) series, respectively, assigned to P=O bonds. For CuO additions ≤20 mol%, the glasses exhibit two bands in the frequency range 780–720 cm−1 which are attributed to the presence of two P–O–P bridges in metaphosphate chain. But for CuO addition ≥30 mol%, the glasses exhibit only a single band at 760 cm−1 which is assigned to the P–O–P linkage in pyrophosphate group. In optical investigations, absorption coefficient versus photon energy showed three regions: low energy side, Urbach absorption, and high energy side. In Urbach’s region, absorption coefficient depends exponentially on the photon energy. At high energy region, optical gap was calculated and investigations showed indirect transition in compounds and decreases in optical gap with increases of copper oxides contents that is because of electronic transitions and increasing of nonbridging oxygen content.  相似文献   

13.
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   

14.
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   

15.
A new spectrofluorimetric method has been developed and validated for the quantification of ceftriaxone in bulk powder, pharmaceutical formulations and spiked human plasma. The developed method is reproducible, accurate, sensitive and cost effective. In this method, ceftriaxone was converted into a fluorescent compound by reacting with 0.8 M ethyl acetoacetate and 25% formaldehyde in a buffered medium (pH = 4.2) at 90 °C. The excitation and emission wavelengths of the fluorescent reaction product are 316 nm and 388 nm respectively. Optimization of the experimental conditions affecting the condensation reaction were carefully carried out and the optimum experimental conditions were incorporated in the procedure. The developed method has a broad linear range (0.2–20 μg mL−1) with a correlation coefficient of 0.9992. The limit of detection (LOD) and limit of quantification (LOQ) was found to be 1.94 × 10−2 μg mL−1 and 6.47 × 10−2 μg mL−1 respectively. The common excipients and co-administered drugs were investigated for their interferences effect in the assay. The developed method was validated statistically through recovery studies and successfully applied to ceftriaxone determination in bulk powder, pharmaceutical formulations and spiked human plasma samples. The percent recoveries were found to be in the range of 99.04–100.26% for bulk powder, 98.88–99.92% for pharmaceutical formulations and 94.22–98.48% for spiked human plasma. The results were verified by comparing with reference literature HPLC method and were found in good agreement.  相似文献   

16.
The structure and phase evolution of nanocrystalline Ce1 x Ln x O2 x/2δ (Ln = Yb, Lu, x = 0 − 1) oxides upon heating in H2 was studied for the first time. Up to 950 °C the samples were single-phase, with structure changing smoothly with x from fluorite type (F) to bixbyite type (C). For the Lu-doped samples heated at 1100 °C in the air and H2, phase separation into coexisting F- and C-type structures was observed for ~0.40 < x < ~0.70 and ~0.25 < x < ~0.70, respectively. It was found also that addition of Lu3+ and Yb3+ strongly hinders the crystallite growth of ceria during heat treatment at 800 and 950 °C in both atmospheres. Valency of Ce and Yb in Ce0.1Lu0.9O1.55δ and Ce0.95Yb0.05O1.975δ samples heated at 1100 °C was studied by XANES and magnetic measurements. In the former Ce was dominated by Ce4+, with small contribution of Ce3+ after heating in H2. In the latter, Yb existed exclusively as 3+ in both O2 and H2.  相似文献   

17.
In pH 1.8 ∼ 2.8 weak acid medium, polyvinylpyrrolidone (PVP) and Eosin Y reacted to form complex that could result in Eosin Y (EY) fluorescence quenching. The maximum quenching wavelength was at 542 nm. The fluorescence quenching (ΔF) was proportional to the concentration of polyvinylpyrrolidone in a certain range. The linear range, the correlation coefficient and the detection limit were 0.33 ∼ 2.0 μg•mL−1, 0.9994 and 99.6 ng•mL−1, respectively. The influences of the coexistence substances were tested and the results showed that the method had good selectivity. Therefore, a new method based on fluorescence quenching of eosin Y by PVP for the determination of trace PVP was developed. The method was sensitive, simple and rapid, which was applied to the determination of trace PVP in the beer with satisfactory results. The reaction mechanism was also discussed.  相似文献   

18.
A simple, sensitive and accurate method has been developed for spectrofluorimetric determination of cefixime in pure form and pharmaceutical preparations. The method is based on the reaction of cefixime with 2-cyanoacetamide in the presence of 21% ammonia at 100 °C. The fluorescent reaction product showed maximum fluorescence intensity at λ 378 nm after excitation at λ 330 nm. The factors affecting the derivatization reaction were carefully studied and optimized. The fluorescence intensity versus concentration plot was rectilinear over the range of 0.02 to 4 μg mL−1 with correlation coefficient of 0.99036. The limit of detection (LOD) and limit of quantification (LOQ) was found to be 2.95 ng mL−1 and 9.84 ng mL−1, respectively. The proposed method was validated statistically and through recovery studies. The method was successfully applied for the determination of cefixime in pure and dosage form with percent recoveries from 98.117% to 100.38%. The results obtained from the proposed method have been compared with the official HPLC method and good agreement was found between them.  相似文献   

19.
BaCe0.7Ta0.1Y0.2O3− δ (BCTY) and BaCe0.8Y0.2O3− δ (BCY) were synthesized by solid-state reaction method at 1,300 °C for 20 h. After being exposed in 3% CO2 + 3% H2O + 94% N2 at 700 °C for 20 h, the BCTY exhibited adequate chemical stability against carbonations while BCY decomposed into BaCO3 and CeO2. The BCTY showed the similar thermal expansion behavior to BCY from room temperature to 1,000 °C in air. The BCTY displayed a conductivity of 0.007 S/cm at 700 °C in humid hydrogen, lower than that of BCY (0.009 S/cm). A fuel cell with 10-μm thick BCTY membrane prepared through an all-solid-state process exhibited 1.004 V for OCV, 330 mW/cm2 for maximum output at 700 °C, respectively. Short-term test shows that the fuel cell performance does not degrade after 20 h.  相似文献   

20.
A high-resolution spectrometer based on a vertical-cavity surface-emitting laser (VCSEL) was developed and used to determine the line strength S(T 0)=12.53(11)×10−21 cm−1/(molec cm−2) and the self-broadening coefficient g0HCl=0.021787(61)\gamma^{0}_{\mathrm{HCl}}=0.021787(61)  cm−1/atm of the R(3) absorption line in the first rovibrational overtone (2←0) band of H35Cl. Furthermore, the first laser-based high-pressure study on the pressure broadening of HCl by He, N2 and O2(g0N2=0.07292(5)\mathrm{O}_{2}(\gamma^{0}_{\mathrm{N}_{2}}=0.07292(5)  cm−1/atm, g0He=0.02113(1)\gamma^{0}_{\mathrm{He}}=0.02113(1)  cm−1/atm, g0O2=0.03978(6)\gamma^{0}_{\mathrm{O}_{2}}=0.03978(6)  cm−1/atm) is presented covering pressures of up to 1 MPa. The results are compared to previously available low-pressure data.  相似文献   

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