Kinetic fluorimetric determination of gliadins in foods

Abstract

Kinetic methodology was applied for the first time to the determination of gliadin proteins by using a stopped-flow mixing technique. The method is based on two simultaneous processes: the reaction between gliadins and sodium dodecyl sulfate and the elimination of the quenching caused by this surfactant of the fluorescence of Cresyl Violet. Thus, the increase in fluorescence intensity with time is directly related to gliadin concentration. The use of this oxazine dye allows dynamic fluorescence measurements at long wavelengths, which avoids potential interferences from the sample matrix. The reaction rate is measured within 5 s, so the method is very suitable for the routine determination of gliadins in food samples. The dynamic range of the calibration graph was 0.5-50 micrograms ml-1 and the LOD was 0.25 microgram ml-1. The RSD was 1.6%. The method was applied to different food samples and the analytical recoveries were 88-107%.

Improvements in europium sensitized fluorimetric determination of demeclocycline and methacycline

“…The effect of several micellar systems on the enhancement of the emission fluorescence of various TC complexes with Eu(III) and Tb(III) has been previously described [17][18][19][20][21][22]. Thus, Georges and Ghazarian [17] proposed the use of Triton X-100.…”

Selective kinetic determination of amikacin in serum using long-wavelength fluorimetry

“…However, the reactivity of these compounds can be improved by electrostatic interactions [21][22][23] or redox reactions [24,25]. Several redox agents such as sodium metaperiodate, hydrogen peroxide and cerium(IV) were assayed with the aim of modifying the fluorescent features of ICG allowing its use as reagent for the selective determination of amikacin.…”

Development and Validation of Europium-Sensitized Luminescence (ESL) Method for the Determination of Tetracycline Residues in Milk

“…Literature based on europium-sensitized fluorescence methods for tetracycline determination in milk is more scarce (Savage et al 1998;Gala et al 1997), and it includes only a few examples of solid-matrix time-resolved luminescence and stopped flow techniques; only recently has the method received renewed attention (Chen and Liu 2004;Traviesa-Alvarez et al 2007). …”