Fluorescence enhancement effect of Eu(III)-thenoyltrifluoroacetone-cetyltrimethyl ammonium bromide in water-dissolved organic matter extracted from wheat straw

The fluorescence spectral characteristics of water-dissolved organic matter extracted from wheat straw (DOM-WS) were studied using three-dimensional excitation-emission matrix (3D-EEM) fluorescence spectroscopy. The results indicated that 3D-EEM spectra of DOM-WS showed four different fluorophores: humic-like, visible fulvic-like, UV fulvic-like and protein-like substances. It is interesting that DOM-WS can obviously enhance the fluorescence intensity of Eu(III)-thenoyltrifluoroacetone-cetyltrimethyl ammonium bromide system. On the basis of this study, a new fluorescence method for the determination of trace amounts of Eu(III) was developed. Under the optimal conditions, the enhanced fluorescence intensity was in proportion to the concentration of Eu(III) in the range of 8.0×10(-8)-8.0×10(-7)mol/L. The detection limit (S/N=3) was 1.1×10(-9)mol/L. This method was applied to the analysis of Eu(III) concentration in standard sample and obtained satisfactory results. It may be a new way to use wheat straw effectively.

Estimation of Eu(3+) in bulk uranium by ligand sensitized fluorescence in dimethyl sulphoxide

Ligand sensitized fluorescence of europium ion using thenoyltrifluoroacetone (TTA) as a sensitizing ligand and dimethyl sulphoxide (DMSO) as a solvent is studied for the first time. TTA ligand enhances the fluorescence of Eu(3+) by a factor of 40000 in DMSO. Linearity is obtained for a concentration range of 0.076-7.6ng/mL of Eu(3+) with a detection limit of 7.6pg/mL. The quenching of Eu(3+)-TTA fluorescence by uranium matrix was studied in different solvents and found to be less in DMSO. Consequently, estimation of Eu(3+) in a large excess of uranium becomes a possibility without the need to separate uranium from the solution, which has been demonstrated in this paper. Satisfactory results are obtained when Eu(3+) is present at a concentration of 0.6μg/g in uranium.

Esterase inhibitors as ester-containing drug stabilizers and their hydrolytic products: potential contributors to the matrix effects on bioanalysis by liquid chromatography/tandem mass spectrometry

RATIONALE

Esterase inhibitors are widely used to stabilize ester-containing drugs in biological matrices for quantitative liquid chromatography/tandem mass spectrometry (LC/MS/MS) assays. These co-existing inhibitors could cause matrix effects on bioanalysis and jeopardize the assay performance. We therefore developed an LC/MS/MS methodology to monitor the fate of inhibitors and evaluate their matrix effects, which is described in this study.

METHODS

Human plasma containing 20 mM of diisopropylfluorophosphate (DFP), paraoxon, eserine, phenylmethylsulfonyl fluoride (PMSF) or 2-thenoyltrifluoroacetone (TTFA) was extracted by liquid-liquid extraction (LLE) and analyzed by an LC/MS/MS assay for BMS-068645 (a model drug) with additional pre-optimized selected reaction monitoring (SRM) transitions using positive/negative electrospray ionization (ESI) mode for each inhibitor. Hydrolytic products were characterized by product ion or neutral loss scan LC/MS/MS analysis. The matrix effect contribution from each inhibitor was evaluated by post-column infusion of BMS-068645.

RESULTS

In the extracted samples by LLE, SRM chromatograms revealed the presence of paraoxon, eserine and TTFA with peak intensity of >2.50E08. Three DFP hydrolytic products, diisopropyl phosphate (DP), triisopropyl phosphate (TP) and DP dimer, and one PMSF hydrolytic product, phenymethanesulfonic acid (PMSA), were identified in the extracted samples. In post-column infusion profiles, ion suppression or enhancement was observed in the retention time regions of eserine (~10% suppression), paraoxon (~70% enhancement) and DP dimer (~20% suppression).

CONCLUSIONS

The SRM transitions described here make it possible to directly monitor the inhibitors and their hydrolytic products. In combination with post-column infusion, this methodology provides a powerful tool to routinely monitor the matrix effects-causing inhibitors, so that their matrix effects on the bioanalysis can be evaluated and minimized.

Synthesis and characterization of a Eu-containing polymer precursor featuring thenoyltrifluoroacetone and 5-acrylamido-1,10-phenanthroline

A polymerizable ligand, 5-acrylamido-1,10-phenanthroline (L), was synthesized. Its Eu(III) complex with 2-thenoyltrifluoroacetone (HTTA) was prepared and characterized by elemental analysis, IR, MS, and (1)H NMR spectra. The photophysical properties of the complex were studied in detail by using UV, luminescence spectra, luminescence lifetime and quantum yield. The complex shows a remarkable luminescence quantum yield at room temperature (40.1%) upon ligand excitation and a long (5)D(0) lifetime (590 μs), which makes it not only a promising light-conversion molecular device but also an excellent luminescent polymer precursor.

The luminescence response of Eu(III)-thenoyltrifluoroacetonate complexes upon preresonant excitation with femtosecond laser pulses

The luminescence of thenoyltrifluoroacetonate (TTA) coordination complexes of trivalent europium ion (Eu(III)) in aqueous solutions and in solid-state polymeric films is probed upon single- and two-photon preresonant excitation with Ti:sapphire femtosecond laser. Particularly, diamine-liganded Eu(III)(TTA)(3) and poly(oxyethylene phosphate)tris(beta-diketonate)Eu(III) complexes are examined aiming their possible applications as luminescent labels for sensing and imaging of biological molecules. Even at a pre-resonance, the excitation of these compounds with high-intensity, broadband light of frequency-doubled Ti:sapphire femtosecond laser centered around 400 nm results in a luminescence response suitable for fluorometric applications.

Enhanced luminescence of Eu(3+) by Y(3+) in ternary complexes Eu(X)Y(1-X)(TTA)3Dipy

Rare-earth ternary complexes Eu(X)Y(1-X)(TTA)3Dipy {X=0, 0.1, 0.25, 0.5, 0.75, 0.9, 1.0, using thenoyltrifluoroacetone (TTA) as ligand and 2,2'-dipyridyl (Dipy) as synergic agent} were synthesized. Characterization with X-ray diffraction (XRD), IR and elemental analysis had also been carried out. The photophysical properties of these complexes were studied in detail with ultraviolet absorption spectra and fluorescent spectra. It is found that the enhanced luminescence of Eu(3+) ions by Y(3+) ions occurs in ternary complexes. And we monitored the spectra of Eu(X)Y(1-X)(TTA)3Dipy (PVK:Eu/BCP/AlQ/Al) at the different rate (rpm). The results showed that the Y(3+) ion acts as an energy transfer bridge that helps energy transfer from PVK to Eu(3+).

Spectrofluorimetric determination of 5-hydroxytryptamine using chlorosulphonylthenoyltrifluoroacetone-europium probe

A new spectrofluorimetric method was developed for the determination of trace amounts of 5-hydroxytryptamine (5-HT). Using chlorosulphonylthenoyltrifluoroacetone (CTTA)-europium (Eu(3+)) ion as a fluorescent probe in a buffer solution at pH 11.0, 5-HT can remarkably enhance the fluorescence intensity of the CTTA-Eu(3+) complex at lambda = 612 nm; the enhanced fluorescence intensity of Eu(3+) is proportional to the concentration of 5-HT. Optimum conditions for the determination of 5-HT were also investigated. The linear range and detection limit for the determination of 5-HT were 1.0 x 10(-7)-1.2 x 10(-5) mol/L and 8.5 x 10(-8) mol/L, respectively. This method is simple, practical and relatively free of interference from coexisting substances, and can be applied to assess 5-HT in urine samples.

Synthesis, spectral, and thermal characterizations of Ni(II) and Cu(II) beta-diketone complexes with thenoyltrifluoroacetone ligand

Two kinds of nickel(II) and copper(II) beta-diketone complexes derived from thenoyltrifluoroacetone ligand with blue-violet light absorption were synthesized by reacting free ligand and different metal(II) ions in sodium methoxide solution. Their structures were postulated based on elemental analysis, ESI-MS, FT-IR spectra and UV-vis electronic absorption spectra. Smooth films on K9 glass substrates were prepared using the spin-coating method. Their solubility in organic solvents, absorption properties of thin film and thermal stability of these complexes were evaluated.

Analysis of Indian blue ballpoint pen inks tagged with rare-earth thenoyltrifluoroacetonates by inductively coupled plasma–mass spectrometry and instrumental neutron activation analysis

Characterization and assessment of inks on sensitive documents for absolute/relative age determination is the challenging forensic problem in spite of practical difficulties. Tagging of ballpoint pen ink with suitable taggant(s) is a unique method to come out with definitive inferences on the detection of forgery in documents written with ballpoint pens. Selection of a proper taggant primarily depends on sensitivity of analytical determination and their absence in normal varieties of ink used for document writing. Rare-earth elements, from all technical considerations can be potential taggant(s) for inks. To ensure more compatibility with ink, 13 rare-earth thenoyltrifluoroacetonate chelates were prepared and characterized. The ballpoint pen inks were tagged with rare-earth thenoyltrifluoroacetonate chelates individually at about 1-100 ppm level depending on sensitivity of element under suitable optimized experimental conditions and instrumental sensitivity. Aliquots of such tagged ink having varying amounts of taggants were analyzed by ICP-MS and INAA. Satisfactory recoveries and a good linear relationship of intensity (signal) against concentrations/amounts were observed. Under the optimized experimental conditions, the detection limits were worked out. This study of tagging metal ions in combination with ICP-MS and NAA as an analytical tool can allow to draw various combination options based on different rare-earth chelates as suitable materials for tagging of ballpoint pen inks for absolute/relative age determination to aid in document related crime examination. The advantages and limitations of proposed analytical techniques are discussed.

The sensitive determination of nucleic acids using a fluorescence-quenching method

Experiments indicated that nucleic acids can quench the fluorescence of the Eu3+ -2-thenoyltrifluoroacetone (TTA)-1,10-phenanthroline (Phen) system. Based on this, a sensitive method for the determination of nucleic acids was proposed. The experiments indicated that under the optimum conditions, the quenched fluorescence intensity was in proportion to the concentration of nucleic acids in the range 1.0 x 10(-11)-1.0 x 10(-6) g/mL for yeast RNA (yRNA), 5.0 x 10(-11)-5.0 x 10(-7) g/mL for fish sperm (fsDNA) and 1.0 x 10(-10)-1.5 x 10(-6) g/mL for calf thymus DNA (ctDNA). Their detection limits were 3.0 x 10(-12), 4.0 x 10(-12) and 5.0 x 10(-11) g/mL, respectively. Therefore, the proposed method is one of the most sensitive methods available. The interaction between nucleic acids and Eu3+ -TTA-Phen is also discussed.

Nitrogenous Synergists Induced Potentiometric Response to Metal Ions with Polymeric Liquid Membranes Containing Thenoyltrifluoroacetone as an Ionophore

The effects of nitrogenous synergists on the potentiometric responses to divalent transition metal ions were investigated concerning polymeric liquid membranes containing thenoyltrifluoroacetone (Htta) as an ionophore. The tested synergists were pyridine (py) and 4,4'-dioctyl-2,2'-bipyridyl (C8bpy). The potentiometric responses to metal ions, such as Cd2+, Co2+, Ni2+ and Zn2+, were induced by adding the synergists into the liquid membrane systems. The coexistence of Htta and a synergist was necessary for generating the membrane potential. The tta- anion adsorbed at the liquid membrane/solution interface and the complex formation between the synergist and a given metal ion appeared to participate in preferential uptake of metal ions.

Selective extraction of naturally occurring radioactive Ra2+

Organic extractants play a significant role in the selective removal of radioactive cations from waste streams. Although, literature on the selective removal of man-made radioactive material such as Americium (Am) is widespread, the selective removal of naturally occurring radioactive material such as Ra2+ is only mentioned sporadically. This tutorial review deals with the selective extraction of the highly radiotoxic Ra2+. Special attention is paid to different types of organic extractants used.

Organophosphate nerve agent detection with europium complexes

We explore the detection of paraoxon, a model compound for nonvolatile organophosphate nerve agents such as VX. The detection utilizes europium complexes with 1,10 phenanthroline and thenoyltrifluoroacetone as sensitizing ligands. Both europium luminescence quenching and luminescence enhancement modalities are involved in the detection, which is simple, rapid, and sensitive. It is adaptable as well to the more volatile fluorophosphate nerve agents. It involves nothing more than visual luminescence observation under sample illumination by an ordinary hand-held ultraviolet lamp.

Trace explosives detection by photoluminescence

Some field tests in counter-terrorism efforts to detect explosive traces employ chemistries that yield colored products. We have examined a test kit of this kind, ETK(Plus), based on widely used chemistries and employed extensively by the Israel Police. Our investigation focuses on the prospect of gaining sensitivity by replacing the normal colorimetric modality with photoluminescence detection, which, to our knowledge, has not been explored to date. We find two or more orders of magnitude sensitivity gains for all explosives studied, using field-worthy photoluminescence techniques. We have also investigated a general lanthanide-based photoluminescence approach which shows promise and the ability to photoluminescence-detect trace explosives in the presence of intense background color and/or background fluorescence by time-resolved imaging.

[Study on the synthesis and spectra of 2-thenoyl-2-carbazolyl-N-butyltrifluoroacetone]

In phene-50% NaOH medium, 1,4-dibromobutane reacts with carbazole (CZ) to form N-bromobutylcarbaole (BCZ) at 70-80 degrees C. The 2-thenoyl-2-carbazolyl-N-butyltrifluoroacetone (TCBTA) was synthesized by reaction of BCZ with 2-thenoyltrifluoroacetone (TTA) in acetone-K2CO3 medium at 50 degrees C. The TCBTA is a light brown crystal with m.p. of 211-214 degrees C. The structure of the synthesized TCBTA was characterized by UV, IR and GC/MS, and the UV and IR spectra of CZ, BCZ and TTA have been studied. In chloroform, TCBTA has three maximum absorptions at 241, 265 and 295 nm whose molar absorptivity is 1.88 x 10(5), 1.25 x 10(5) and 1.08 x 10(5) L x mol(-1) x cm(-1), respectively. Extraction rate of iron(III) and neodymium(III) by TCBTA in chloroform rises by 3 and 1.6 times compared with TTA. The fluorescence of TCBTA-Nd(III) complex is 5 times higher than TTA-Nd(III) complex. It was shown that TCBTA has excellent photosensitivity.

Low-temperature electrothermal vaporization of thenoyltrifluoroacetone complex of Sc(III) and Y(III) for sample introduction in an inductively coupled plasma atomic emission spectrometry, and their determination in biological samples

A new method for inductively coupled plasma atomic emission spectrometry (ICP-AES) determination of trace Sc and Y, based on gaseous compound introduction into the plasma as their thenoyltrifluoroacetone (TTA) complexes by electrothermal vaporization was developed. Using the reagent TTA as chemical modifier can not only enhance the analytical signals, but also reduce the vaporization temperature. At a temperature of 1,000 degrees C the trace Sc and Y can be vaporized completely into ICP. The factors affecting the formation of the chelate and its vaporization behavior, such as drying time, vaporization temperature/time, reaction medium and the amount of TTA, were investigated in detail. Under the optimized conditions (drying temperature/time 100 degrees C/10 s, vaporization temperature/time 1,000 degrees C/4 s), the limits of detection for Sc and Y were 19 pg and 34 pg (3sigma), respectively, and the relative standard deviations for Sc and Y were 4.2% (cSc=0.2 microg mL(-1); n=7) and 2.6% (cY=0.5 microg mL(-1); n=7). The linear ranges of the calibration graphs cover three orders of magnitude. The method was applied to the analysis of the biological reference materials (GBW 07602, bush branches and leaves; GBW 07604, poplar leaves), and the results obtained were in good agreement with the certified values.

Comprehensive study of the luminescent properties and lifetimes of Eu(3+) and Tb(3+) chelated with various ligands in aqueous solutions: influence of the synergic agent, the surfactant and the energy level of the ligand triplet

The formation and the properties of luminescent complexes of europium and terbium with a variety of organic ligands have been investigated in aqueous solutions. The ligands used include model compounds such as thenoyltrifluoroacetone and pyridine-2,6-dicarboxylic acid and organic analytes of biological or pharmaceutical interest. It is shown that the formation and the luminescent properties of these complexes depend at first on several parameters including the pH and the buffer, the synergic agent and the surfactant. In neutral solutions, trioctylphosphine oxide in the presence of Triton X-100 may act as a co-ligand to promote complex formation and protect the complex from radiationless deactivation processes. Working in slightly alkaline solutions in the presence of EDTA and hexadecyltrimethylammonium chloride may induce the deprotonation of a second coordinating group and favour the formation of a new complex with stronger luminescent properties. In both cases, the luminescence lifetimes are then ultimately related to the energy gap between the ligand triplet and the resonance level of the ion and to the number of water molecules coordinated to the lanthanide ion.

Synthesis and photophysical study of highly luminescent coordination compounds of rare earth ions with thenoyltrifluoroacetonate and AZT

This work presents the study of the interaction between zidovudine (AZT) and rare earth (RE) ions with thenoyltrifluoroacetonate (TTA). The complexes [RE(TTA)(3) x (AZT)(2)] (where RE(III)=Eu and Gd) were prepared by reaction between the [RE(TTA)(3) x (H(2)O)(2)] precursors and AZT dissolved in acetone in the molar ratio 1:2. The obtained luminescent materials were characterized by microanalyses (C, H, N), complexometric titration, IR spectroscopy, X-ray powder diffraction and thermal analysis (DSC and TG/DTG). The luminescence data indicate that the substitution of the two water molecules by AZT in the europium complex causes an intensification of luminescence corresponding to the (5)D(0) -->(7)F(J) (J=0-4) transitions associated with one of the site symmetries. Based on the luminescence spectrum of the Eu(III)-compound the Omega(lambda) experimental intensity parameters (lambda=2 and 4) were calculated for the electronic transitions (5)D(0)-->(7)F(2, 4). The Omega(2) intensity parameter for this new compound is higher than for the precursor compound, suggesting an effective interaction between the AZT and the chemical environment of the Eu(III) ion. Luminescence data confirm that the AZT complex and precursor compound have a comparable emission quantum efficiency.

[Fluorescence spectra of the rare earth complex-PAA-g-PE films]

The acrylic acid (AA) was grafted onto the PE film surface through UV photograft polymerization. With certain pH value, the grafted films were made to react with the alcohol-water solution of Eu3+ and alpha-thenoyltrifluoroacetone (TTA) or with the chloroform-water solution of Tb3+ and acetyl actone (AcAc), thus causing the preparation of the red or green fluorescent films. As compared with the corresponding Eu(TTA)3.(H2O)2 or Tb(AcAc)3.(H2O)2 solid complexes, both the excitation and emission spectra of the fluorescent films changed remarkably. It's predictable that chemical bond combination has occurred between the rare earth complexes and the macromolecular material. In addition, the IR spectra of the fluorescent films were also observed.

[Electroluminescence and photoluminescence studies on the europium complex of multiple ligands]

A kind of new complex Eu-TTA-B was synthesized (B is a compound containing P = O group). Its coordination structure and fluorescent properties were studied by FTIR and photo-luminescent measurements. Furthermore, single-layer electroluminescent device of Eu complex was prepared and the electroluminescent properties were investigated.

[FTIR and fluorescence studies on the europium complexes of multiple ligands]

A series of EuA(m).nB complexes with different molar ratio of ligands and various concentrations of protecting agent were synthesized (A is thenoyltrifluoroacetone, B is a kind of P = O group compound). The properties of these complexes were investigated by FTIR and fluorescence spectroscopy. The fluorescent intensity of complex is related to the reaction condition, the components of complexes.

Investigation of chelate formation, intramolecular energy transfer and luminescence efficiency and lifetimes in the Eu-thenoyltrifluoroacetone-trioctylphosphine oxide-Triton X-100 system using absorbance, fluorescence and photothermal measurements

The formation and the photophysical properties of the europium-thenoyltrifluoroacetone (TTA) trioctylphosphine oxide (TOPO)-Triton X-100 chelate were investigated. When the medium is buffered with acetate, there is a strong competition between acetate and TTA for coordination with europium ions. When TOPO is added into the solution, the Eu-TTA-TOPO ternary chelate forms more easily, probably because the coligand acts as a synergic agent and would favour the formation of the enol form of TTA. Although the stoichiometric composition of the chelate is expected to be Eu(TTA)3(TOPO)2, the Eu-TTA and the Eu-TOPO mole ratios may be within 2-3 and 1-2, respectively, depending on the composition of the solution. However, the fluorescent properties of the chelate seem to be mainly dominated by its actual concentration into the solution rather than by its composition. Time resolution of europium emission spectra in the microsecond range has shown that energy transfer occurs from the TTA ligand to the 5D1 level of europium. Then, the emitting 5D0 level is populated through non-radiative deactivation of 5D1. The observed lifetimes of the 5D1 and 5D0 states are 1.25 and 860 micros, respectively. The overall fluorescence quantum yield of the chelate, measured by the photothermal method, is found to be 0.22. On the basis of the time-resolved photothermal experiments, the fluorescence quantum yield of the 5D0 state is expected to be > 0.8 and the energy transfer efficiency < 0.28.

Arylamination and arylation of 4,4,4-trifluoro-1-phenyl-1,3-butanedione with N-acetoxy derivatives of 2-aminofluorene

The present study investigated the reaction of carcinogenic electrophiles with beta-diketones which possess an active methylene group. N-Acetoxy-2-(acetylamino)fluorene bound to tRNA at 37 degrees C, pH 7.0, and this reaction was inhibited by 4,4,4-trifluoro-1-phenyl-1,3-butanedione or 2-thenoyltrifluoroacetone. N-Acetoxy-2-(acetylamino)fluorene reacted with these active methylene compounds to form transitory 3-substituted 2-(acetylamino)fluorene intermediates, which, following cleavage of the trifluoroacetyl group, yielded 3-phenacyl-2-(acetylamino)fluorene or 3-(2-thenoylmethyl)-2-(acetylamino)fluorene. N-Acetoxy-2-[(trifluoroacetyl)amino]fluorene reacted with 4,4,4-trifluoro-1-phenyl-1,3-butanedione to yield two products, N-phenacyl-1-(trifluoroacetyl)-2-aminofluorene and N-phenacyl-3-(trifluoroacetyl)-2-aminofluorene. The ratio of these two products was approximately 1:2. The same N-phenacyl products were produced by incubation of the beta-diketone, N-hydroxy-2-(acetylamino)fluorene, and rat liver cytosol which catalyzed the formation of N-acetoxy-2-aminofluorene. Thus, the inhibitions by beta-diketones of nucleic acid-binding and bacterial mutagenesis of carcinogens are likely due to their trapping of the carcinogens.