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Fluorescence Determination (fluorescence + determination)

Distribution by Scientific Domains
Chemistry83%

Selected Abstracts

Fluorescence determination of N -acetylaspartic acid in the rat cerebrum homogenate using high-performance liquid chromatography with pre-column fluorescence derivatization

BIOMEDICAL CHROMATOGRAPHY, Issue 1 2009
Takeshi Fukushima
No abstract is available for this article. [source]

Fluorescence determination of N -acetylaspartic acid in the rat cerebrum homogenate using high-performance liquid chromatography with pre-column fluorescence derivatization

BIOMEDICAL CHROMATOGRAPHY, Issue 1 2008
Takeshi Fukushima
Abstract N -Acetyl- l -aspartic acid (NAA) is an endogenous compound, and its brain concentration is suggested to be altered in neurological disorders. In the present study, a fluorescence determination method for NAA was developed by employing reversed-phase high-performance liquid chromatography (HPLC) with pre-column fluorescence derivatization using 4- N,N -dimethylaminosulfonyl-7- N -(2-aminoethyl)amino-2,1,3-benzoxadiazole (DBD-ED). Using methylsuccinic acid as the internal standard, a linear calibration curve for NAA was constructed in the range 125,1000 µm (n = 3). The detection limit on the column was approximately 5.0 fmol (signal-to-noise ratio 3). The proposed HPLC method was applied to determine NAA in the rat cerebrum homogenate. Cerebrum NAA was successfully determined using 10 µL of the homogenate, and the validation data for the proposed HPLC method demonstrated satisfactory results. Intra- and inter-day precision and accuracy were within 1.1,7.0 and ,8.1,6.3%, respectively. The concentration of NAA in the male rat cerebrum (13 weeks old) was 84 ± 4.6 µmol/mg protein (n = 3). Copyright © 2007 John Wiley & Sons, Ltd. [source]

Study on macromolecular lanthanide complexes (V): Synthesis, characterization, and fluorescence properties of lanthanide complexes with the copolymers of styrene and acrylic acid

JOURNAL OF APPLIED POLYMER SCIENCE, Issue 2 2009
Xing Liang
Abstract In this study, the luminescent macromolecular lanthanide complexes Ln-PSt/AA (Ln = Eu and Tb; St = styrene; AA = acrylic acid) have been synthesized, and an extensive characterization has been carried out by means of elemental analysis, FTIR, thermal analysis, and fluorescence determination. The results showed that the carboxylic groups on the chain of the polymers acted as bidentate ligands coordinated to lanthanide ions; and the coordination degree of COO,/Ln3+ in the macromolecular complexes was closely dependent on both the pH value of the solution and the molar ratio of St to AA in the polymeric ligands. Thermal analysis manifested that these Ln-PSt/AA (Ln = Eu and Tb) complexes had high thermal stability and solvent resistance, and these macromolecular complexes were highly crosslinked. The fluorescence determination indicated that Ln-PSt/AA complexes could emit characteristic fluorescence with comparatively high brightness and good monochromaticity, and the fluorescence intensity changed with increasing lanthanide ions content. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009 [source]

Performance characteristics according to Commission Decision 2002/657/EC in the fluorimetric determination of tetracycline in the absence and in the presence of magnesium

LUMINESCENCE: THE JOURNAL OF BIOLOGICAL AND CHEMICAL LUMINESCENCE, Issue 6 2007
Noelia Rodríguez
Abstract The fluorimetric determination of tetracycline is usually carried out in the presence of some metals that, through the formation of a complex with this antibiotic, enhance its fluorescence emission, giving more sensitive determination methods. It is well established that magnesium is one of these metals. However, it is possible that higher signals do not mean a real improvement in the quality of the analytical method. In this work, the univariate and multivariate fluorescence determination of tetracycline is performed in the presence and absence of Mg2+, comparing the quality of the analyses through some performance characteristics that, according to Commission Decision 2002/657/EC define the functional qualities of analytical methods. The methods with the best performance characteristics were multivariate determinations carried out in the absence of Mg2+, both when emission or excitation spectra were taken, the decision limits (CC,) being 13.1 and 20.1 µg/L and the detection capabilities (CC,) 25.3 and 38.5 µg/L, respectively. This study points out through a case study that higher analytical signals do not necessarily mean better performance characteristics of a method of analysis. Copyright © 2007 John Wiley & Sons, Ltd. [source]

Dimer,monomer equilibrium of human thymidylate synthase monitored by fluorescence resonance energy transfer

PROTEIN SCIENCE, Issue 5 2010
Filippo Genovese
Abstract An ad hoc bioconjugation/fluorescence resonance energy transfer (FRET) assay has been designed to spectroscopically monitor the quaternary state of human thymidylate synthase dimeric protein. The approach enables the chemoselective engineering of allosteric residues while preserving the native protein functions through reversible masking of residues within the catalytic site, and is therefore suitable for activity/oligomerization dual assay screenings. It is applied to tag the two subunits of human thymidylate synthase at cysteines 43 and 43, with an excitation energy donor/acceptor pair. The dimer,monomer equilibrium of the enzyme is then characterized through steady-state fluorescence determination of the intersubunit resonance energy transfer efficiency. [source]

Liquid chromatographic fluorescence determination of amino acids in plasma and urine after derivatization with phanquinone

BIOMEDICAL CHROMATOGRAPHY, Issue 2 2008
Rita Gatti
Abstract Phanquinone (4,7-phenanthroline-5,6-dione) has been investigated as a pre-column derivatization fluorogenic reagent for liquid chromatographic determination of primary amino acids in biological samples. The derivatization reaction was carried out at 68°C both in the presence of aqueous phosphate buffer (pH 8) for 30 min and without buffer for 60 min to allow the determination of basic amino acids (Orn, Lys, Arg). The resulting derivatives were separated under reversed-phase HPLC and detected at ,em = 460 nm with ,ex = 400 nm. The proposed method was validated and applied to the determination of a variety of amino acids directly in urine and after deproteinization with 5-sulfosalicylic acid in plasma samples. The detection and quantitation limits were found in the range 10,450 and 35,1400 fmol, respectively. Copyright © 2007 John Wiley & Sons, Ltd. [source]