Abstract The hydrophilic and lipophilic antioxidant activities due to the main bioactive components present in Spanish tomato paste samples were studied, using standardized fluorescent methods. After extraction, phenolic antioxidants (Folin-Ciocalteu method) total activity (TEAC assay) evaluated, examining differences between extracts corresponding different samples. Total fluorescence spectra ...

Fluorescence emission and excitation spectra were measured over a 7-day period for Bacillus subtilis (Bs), a spore-forming, and Staphylococcus aureus (Sa), a nonspore-forming bacteria subjected to conditions of starvation. Initially, the Bs fluorescence was predominantly due to the amino acid tryptophan. Later, a fluorescence band with an emission peak at 410 nm and excitation peak at 345 m, fr...

6MAP is a fluorescent analogue of adenine that undergoes Watson-Crick base pairing and base stacking in double-stranded DNA. The one-photon absorption spectrum of 6MAP is characterized by a maximum around 330 nm with moderate quantum yield fluorescence centered at about 420 nm. To take advantage of this probe for confocal and single-molecule microscopy, it would be advantageous to be able to ex...

a new sensitive, simple and rapid method for determination of methotrexate (mtx) was developed based on quenching effects of mtx on the fluorescence intensity of tb3+-1,10-phenanthroline complex. the fluorescence intensity was measured with excitation wavelength of 300 nm and emission wavelength of 545 nm and the quenched fluorescence intensity is proportional to the concentration of mtx in tris...

A thorough analysis of the photophysical properties involved in electronic transitions in excitation-emission spectra of xylene isomers has been carried out using the time-dependent density functional theory (PBEPBE/6-31 + G(d,p)) method. For the first time a structural and spectroscopic investigation to distinguish isomers of xylene, a widespread priority pollutant, was conducted experimentall...

The fluorescence kinetics of 1,6-diphenyl-1,3,5-hexatriene (DPH) dissolved in cyclohexane was investigated as a function of temperature, concentration and 355 nm excitation pulse energy. At concentrations above 2.5 μM and excitation energies above 1 mJ a long-lived, very intense emission, which appears within less than 5 ns and lasts up to 70 ns, is observed. During the first 50 ns the decay do...

Fluorescence and fluorescence excitation spectra of all-trans-2,4,6,8-decatetraene have been obtained in free jets and in inert-gas clusters. In isolated decatetraene, excitation into 1 ‘B, (S, ) results in emission from both S, ( 1 ‘B, + 1 ‘A, ) and S, (2 ‘A, --) 1 ‘A, ) on time scales that are faster than the 10 ns experimental resolution. In clusters, rapid electronic and vibrational relaxat...

Steady-state fluorescence spectroscopy is highly sensitive an analytical fluorescence detecting tool limited to diluted samples. The serious problem of quantitative analysis is dominant in the samples with optical density higher than 0.05 (10 mm cell) detected in the right angle cell geometry, because of the two kinds of inner filter effects IFEs (Lakowicz, 2006; Li & Hu, 2007; Kao et al., 1998...