铕-环丙沙星的稀土敏化荧光研究及应用

在pH 7.4 NH3·H2O-NH4Cl缓冲溶液中, Eu(Ⅲ)与环丙沙星反应形成1∶2的稳定缔合物, 产生稀土敏化荧光现象, 其最佳激发、发射波长分别为λex=355 nm、λem=612 nm. 在该反应体系中加入适量维生素M溶液, 使Eu(Ⅲ)与环丙沙星缔合物的荧光发生猝灭. 利用这一现象, 建立了测定维生素M的荧光分析方法. 该方法保持了维生素M结构的完整性, 维生素M浓度在1.0×10-7～7.0×10-6 mol/L范围内符合线性关系, 检出限4.4×10-8 mol/L. 该方法用于片剂及胶囊中维生素M含量的测定, 6次平行测定回收率为95.7%～103.0%, 相对标准偏差为0.99%～1.4%.     

铽-环丙沙星-SDS敏化荧光猝灭法检测雷公藤红素

在pH=9.26的氨-氯化铵缓冲溶液中,铽Ⅲ与环丙沙星反应形成络合物,而后加入十二烷基硫酸钠(SDS)形成了三元体系,其最佳激发、发射波长分别为λex= 330nm、λem=545 nm.在该反应体系中加入适量雷公藤红素溶液,铽Ⅲ与环丙沙星络合物的激发、发射波长位置不变,但荧光强度有规律下降.利用这一现象,建立了测定雷...     

Fluorimetric determination of aminoglycoside antibiotics using lanthanide probe ion spectroscopy

The application of probe ion fluorimetry has succeeded in the microdetermination of six aminoglycoside antibiotics: neomycin, streptomycin, gentamicin, tobramycin, amikacin and kanamycin as sulfate salts in pure form and in some pharmaceutical preparations. The method is based on the reaction of Eu³⁺ ions with aminoglycosides through amino and hydroxy groups. Such interactions enhance the intensity of the 616 nm fluorescence emission of the Eu³⁺ ion. The fluorescence at 592 nm comes from a non-hypersensitive transition and is not affected by the ligand which is bound to the probe ions. The intensity ratio R, defined as I₅₉₂/I₆₁₆ was used to determine the amount of free and bound europium ions. A linear relationship between bound europium ions and aminoglycoside was found within the concentration ranges 20–100 ppm for neomycin, 5–60 ppm for streptomycin, and 10–70 ppm for gentamicin, tobramycin, amikacin, and kanamycin as sulfate salts. The percentage recoveries ranged from 99.22 to 101.07, with standard deviations ranging from ± 1.5 to ± 4.38. The relative stability constants ranged from 5 × 10³ to 2 × 10⁴. The optimum reaction conditions were studied and the results obtained compared favourably with the fluorimetric method using fluorescmine reagent.     

Bis-intercalation-triggered fluorescence: specific detection of double stranded DNA and AT content estimation

Detection of double stranded DNA and estimation of the AT content in DNA of unknown concentration could be achieved with a bis-acridinyl peptide carrying fluorescein, FKA.     

Determination of warfarin by sensitized fluorescence using organized media

The effect of surfactant micelles and albumin on the fluorescence warfarin of and the fluorescence of Eu³⁺ and Tb³⁺ sensitized by warfarin and the second ligand is studied. It was shown that sensitized fluorescence in the system Eu³⁺-tenoyltrifluoroacetone-warfarin allows a 3800-fold reduction of the detection limit for warfarin. The developed procedure was used to determine warfarin in soil.     

Determination of nucleic acids using fluorescence probe sensitized by microemulsion

Because the fluorescence of azur A can be quenched by adding nucleic acid, a sensitive fluorometric method for determination of nucleic acids at nanogram levels was established. Using optimal conditions, the calibration curves were linear in the range of 0-6.0 microg/mL for calf thymus deoxyribonucleic acid (ct DNA) and 0-7.0 microg/mL for herring sperm DNA (hs DNA). The limits of determination were 3.5 and 3.8 ng/mL, respectively, which shows the high sensitivity of this method. Triton X-100 microemulsion was applied as a sensitive media to enhance the sensitivity. The binding mode concerning the interactions of azur A with nucleic acids was also studied and the association constant with different binding numbers was obtained. The method has been applied to the determination of nucleic acid in both synthetic and real samples, such as cauliflower and pork liver, with satisfactory results.     

Quantitative detection of well-based DNA array using switchable lanthanide luminescence

In this report a novel wash-free method for multiplexed DNA detection is demonstrated employing target specific probe pairs and switchable lanthanide luminescence technology on a solid-phase array. Four oligonucleotide capture probes, conjugated at 3′ to non-luminescent lanthanide ion carrier chelate, were immobilized as a small array on the bottom of a microtiter plate well onto which a mix of corresponding detection probes, conjugated at 5′ to a light absorbing antenna ligand, were added. In the presence of complementary target nucleic acid both the spotted capture probe and the liquid-phase detection probe hybridize adjacently on the target. Consequently the two non-luminescent label molecules self-assemble and form a luminescent mixed lanthanide chelate complex. Lanthanide luminescence is thereafter measured without a wash step from the spots by scanning in time-resolved mode. The homogeneous solid-phase array-based method resulted in quantitative detection of synthetic target oligonucleotides with 0.32 nM and 0.60 nM detection limits in a single target and multiplexed assay, respectively, corresponding to 3× SD of the background. Also qualitative detection of PCR-amplified target from Escherichia coli is described.     

铽-敏化荧光法测定妥舒沙星

依据Tb3+和妥舒沙星 (TSLX)形成配合物并在分子内发生能量转移 ,产生Tb3+的特征荧光 ,建立了一种分析妥舒沙星含量的的新方法。方法的线性范围为 7.0× 1 0 - 8～ 5 .0× 1 0 - 6 mol·L- 1 ,检出限为 8.5× 1 0 - 9mol·L- 1 。测定了胶囊中妥舒沙星的含量和回收率 ,回收率在 99.8%～ 1 0 4 %之间。并对Tb3+ 妥舒沙星体系敏化荧光的机理进行了探讨。     

荧光光度法测定核酸的研究进展

对荧光光度法分析检测核酸的基本原理及研究进展进行了综述。讨论了荧光染料、金属离子、金属络合物及纳米粒子等荧光探针在核酸检测中的应用,引用文献51篇。     

Fluorimetric estimation of acridine in airborne and other particilates

Summary Two methods are described for the separation of acridine from organic airborne particulates or coal-tar-pitch. A basic fraction was not necessary for these analyses. With the help of instant thin-layer chromatography (ITLC) with glass-fiber paper impregnated with silica gel, acridine was separated in 18 minutes from the tens of thousands of other compounds in the sample. Separation by paper electrophoresis required about 100 minutes, but the separation was sharper in that acridine and an alkylacridine were separated from each other and also from the quinolinic compounds above them, the larger aza arenes below them, and the innumerable non-basic compounds at the origin. After separation, the samples were assayed by scanning the standard and unknown acridine spots at F 345/475. Although the electrophoretic method requires more time, it is superior to the ITLC method for estimation of acridine in samples from urban air and from source effluents.

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Zusammenfassung Zwei Methoden zur Abtrennung von Acridin aus organischen Luftverunreinigungsteilchen oder aus Teerpech wurden beschrieben. Die Gewinnung einer basischen Fraktion war hierzu nicht nötig. Auf mit Kieselgel imprägniertem Glasfaserpapier wurde Acridin dünnschichtchromatographisch in 18 Minuten von den zahllosen anderen in der Probe enthaltenen Verbindungen getrennt. Die papierelektrophoretische Trennung erfordert 180 Minuten, ist aber schärfer, da Acridin und ein Alkylacridin voneinander, von den darüberliegenden Chinolinverbindungen, den Azaarenen darunter und von den zahllosen nicht basischen Verbindungen am Start getrennt werden. Nach der Trennung wurden die Acridinflecken durch Fluoreszenzmessung mit Standardproben verglichen. Wiewohl die Elektrophorese mehr Zeit beansprucht, ist sie der raschen Dünnschichtchromatographie bei der Bestimmung von Acridin in Stadtluftproben und technischen Abfallprodukten überlegen.

     

Ultrafast fluorescence studies of dye sensitized solar cells

Time-resolved fluorescence spectra from the RuN719 dye exhibit very short lifetimes (<30 fs) in solutions, on non-injecting substrates and on injecting ones. This reveals <10 fs intramolecular energy redistribution competing with the injection. We conclude that injection proceeds on a sub-10 fs time scale from non-thermalized levels of the dye.     

Time-resolved fluorescence and sensitized fluorescence of oreintationally disordered 2,3-dimethylnaphthalene single crystals

Time-resolved fluorescence spectroscopy has been applied to study the singlet energy transfer in the orientationally disordered undoped 2,3-dimethylnaphthalene (DMN) and DMN : anthracene (DMN : A) mixed crystals (10⁻⁷-3×10⁻² mole/mole) between helium and room temperature. The disorder causes a distribution of molecular excited states (fwhm ≈ 250 cm⁻¹), in which time-resolved spectral diffusion is directly observed within the first two nanoseconds at low temperatures. Temperature-dependent energy transfer is monitored via singlet-singlet annihilation in undoped DMN and via sensitized fluorescence in DMN : A. A transition from predominant dispersive transport at low temperatures to diffusive transport at higher temperatures is discussed quantitatively. In the limiting case of both high guest concentration and low temperature, Förster-type energy transfer is identified from the characteristic time and concentration dependences.     

DNA microelectrophoresis using double focus fluorescence correlation spectroscopy

Double focus fluorescence correlation spectroscopy (dfFCS) was used to determine electrophoretic mobilities of short double-stranded DNA (dsDNA)-fragments (75 base pairs (bp) -1019 bp) in microfluidic channels. The electrokinetic flow profile across a microchannel was measured with 1 microm spatial resolution and separated in electroosmotic and electrophoretic contributions. Experiments show that the free solution mobility is independent of DNA length. The diffusion constant is additionally determined by FCS and follows a length dependent rod-diffusion model. We interpret the electrophoretic mobilities using a modified Nernst Einstein relation, which additionally takes Manning condensation and counterion induced hydrodynamic retardation forces into account. In 3% w/v polyethylene oxide (PEO)-network (M(r) 3 .10(5) Dalton) the electrophoretic velocities become size-dependent with a power-law exponent be-tween 0.28 and 0.31. Mixtures of dsDNA-fragments exhibit distinguishable peaks in the dfFCS cross-correlation function. The potential of dfFCS for realtime micro-analysis in terms of speed and spatial resolution is discussed.     

Synthesis,characterization and fluorescence of lanthanide Schiff-base complexes

Six new lanthanide Schiff-base complexes were synthesized by reactions of hydrated lanthanide nitrates with H₂L (H₂L?=?N,N′-bis(salicylidene)-1,2-cyclohexanediamine) and characterized by elemental analysis, DTA–TG, IR, UV and luminescence spectra. The microanalyses and spectroscopic analyses indicate a 1D polymeric structure with the formula of [Ln(H₂L)(NO₃)₃(MeOH)₂] _n [Ln?=?La (1), Ce (2), Pr (3), Sm (4), Gd (5) & Dy (6)]. The fluorescence spectrum of complex 4 exhibited Sm³⁺ centered, Schiff-base sensitized orange fluorescence, indicating that energy levels of the triplet state of H₂L match closely to the lowest excited state (⁴G_5/2) of Sm³⁺ ion.     

Fluorimetric determination of cyclofenil using photochemical derivatization

In this work, a fluorimetric approach for the determination of cyclofenil, 4-4′-(cyclohexylidenemethylene)bis(phenylacetate), is presented. The method was based on the intense fluorescence (250/410 nm) observed after a UV photochemical treatment of cyclofenil. The influence of the pH and solvent system and UV exposure time on the fluorescence magnitude was studied. Optimization of parameters was made using experimental design (factorial design and central composite design). Limit of detection (3S_b/m) were estimated to be 1.1 × 10⁻⁸ mol L⁻¹ with the linear dynamic range extending up to 8 × 10⁻⁵ mol L⁻¹. This analytical approach was tested through the analysis of a commercial pharmaceutical formulation. In this case, tests enabled an average recovery of 98.3 ± 3.9% (for n = 9) using the analytical curve. The identification of the fluorescent derivative is proposed based on results achieved from GC-MS.     

A sequential injection method for the determination of piroxicam in pharmaceutical formulations using europium sensitized fluorescence

A simple, selective and sensitive luminescence method for the assay of piroxicam (PX) in pharmaceutical formulation is developed. The method is based on the luminescence sensitization of europium (Eu³⁺) by complexation with PX. The signal for PX–EU is monitored at λ_ex=358 nm and λ_em=615 nm. Optimum conditions for the formation of the complex in methanol were 0.01 M TRIS buffer and 0.2 mM of Eu³⁺ which allows the determination of 100–2000 ppb of pX in batch method and 100–1000 ppb with limit of detection (LOD) = 23.0 ppb using sequential injection analysis (SIA). The relative standard deviations of the method range between 2 and 3% indicating excellent reproducibility of the method. The proposed method was successfully applied for he assay of PX in pharmaceutical formulations (Feldene capsules and tablets). Average recoveries of 101.0±0.3 and 98.8±2.7% were obtained for capsules in methanol using batch and sequential injection (SI) methods, respectively.     

Ionic liquid sensitized fluorescence determination of four isoquinoline alkaloids

The fluorescence spectra of berberine, palmatine, jatrorrhizine, and coptisine in ionic liquids were studied and found to increase significantly in ionic liquids, with [C(8)MIM][PF(6)] having the greatest increase. Further studies showed that these drugs could be extracted from an aqueous solution by [C(8)MIM][PF(6)] using the temperature-assisted ionic liquid dispersive liquid phase microextraction method. The enrichment factors were 81.8-82.3, and the extraction recovery was 98.5%, 98.1%, 98.3%, and 98.8% for berberine, palmatine, jatrorrhizine, and coptisine, respectively. Based on the [C(8)MIM][PF(6)] preconcentration, separation, and sensitized fluorescence for these drugs, a new selective and sensitive method for the determination of concentration of these four drugs in aqueous samples was presented. At optimum conditions, the linear relationship was obtained in the ranges of 0.8-130 ng mL(-1), 0.9-160 ng mL(-1), 0.7-140 ng mL(-1), and 0.6-110 ng mL(-1), respectively. The proposed method was successfully applied for the determination of the drugs in pharmaceutical preparations, urine, and plasma samples.     

A lanthanide sensitized chemiluminescence method of flow-injection for the determination of ulifloxacin and prulifloxacin

A lanthanide sensitized chemiluminescence method of flow-injection was developed for the determination of a new fluoroquinolone, ulifloxacin (UFX), and its prodrug prulifloxacin (PUFX). The proposed method was based on the remarkable chemiluminescence enhancement effect of UFX (PUFX) on KMnO₄−Na₂S₂O₄−Ln(III). Tb(III) ion was chosen from lanthanides because it showed the best sensitizing effect. Under optimized experimental conditions, the relative chemiluminescence intensity was in linear relationship with UFX and PUFX concentrations in the ranges of 1.0 × 10⁻⁸ − 5.0 × 10⁻⁶ M and 9.0 × 10⁻⁹ − 5.0 × 10⁻⁶ M, respectively. The minimum detectable value and relative standard deviation were 5.5 × 10⁻⁹ M, 1.5% for UFX and 7.0 × 10⁻⁹ M, 2.9% for PUFX, respectively. The proposed method was applied to the determination of UFX in spiked human serum and urine, and of PUFX in tablets with satisfactory results. The possible mechanism of chemiluminescence was also proposed. The text was submitted by the authors in English.     

Determination of water content in silica nanopowder using wavelength-dispersive X-ray fluorescence spectrometer

A wavelength-dispersive X-ray fluorescence (WDXRF) technique that uses the scattered radiation of the X-ray tube lines and the fluorescence radiation of an element present in a powder sample is proposed as a non-destructive method for the determination of the water content in silica powder. Although direct X-ray fluorescence analysis of water using WDXRF is not adequate for the quantitative determination of water in powder, due to the very low fluorescence yield for hydrogen and oxygen, the fluorescence signal of silicon (Si) in silica powder is attenuated by water, and is shown to decrease in proportion to the water content in silica powder. In addition, it is demonstrated that the Compton- and Rayleigh-scattering of the X-ray tube lines is proportional to the water content. The coefficients of determination, R², of the linear regression equations obtained from the calibration curves for all individual scattered radiations and for the fluorescence radiation of Si were > 0.90. The sum of the peak intensities of the four scattering signals, i.e. the Rayleigh-scattered Rh K–L_2,3 and Rh K–M_2,3 lines, and Compton-scattered Rh K–L_2,3 and Rh K–M_2,3 lines, also showed fairly good linearity and sensitivity over a very wide range of water content from 0 wt.% to 61.5 wt.%. However, porosity had a significant effect on the X-ray signal at low water content, in the range from 0 wt.% to 7.5 wt.%, where the sensitivity for the silica nanopowder with well-defined mesopores (~ 3 nm in diameter) decreased to 0.40 kcps/wt.%, from 0.99 kcps/wt.% for the non-porous silica nanopowder. The use of the Si fluorescence signal along with the scattered radiation of the X-ray tube lines expands the applicability of conventional XRF spectrometers to the quantitative determination of water content in silica powder.