CAFFEINE MONITORING IN BIOLOGICAL FLUIDS AND DIETARY SUPPLEMENTS BY SOLID SURFACE FLUORESCENCE USING RHODAMINE AND NANOTUBES MODIFIED MEMBRANES

TALÍO, MARÍA CAROLINA; ALESSO, MAGDALENA; ACOSTA, MARIANO; ACOSTA, GIMENA; LUCONI, MARTA; FERNANDEZ, LILIANA

CLINICA CHIMICA ACTA

ELSEVIER SCIENCE BV

Lugar: Amsterdam; Año: 2013 vol. 425 p. 42 - 47

0009-8981

Background: In thiswork, a newmethodology based upon enhancement of rhodamine B fluorescent signal is proposed for the quantification of caffeine traces. Methods:Membrane filters treated with multiple wall carbon nanotubeswere employed as solid support for determination step by solid surface fluorescence. Results: Experimental variables that influence the preconcentration step and fluorimetric sensitivity have been optimized using uni-variation assays, presenting linearity from 1.1 to 9.7 × 103 μg/l, with a correlation coefficient of 0.99. At optimal conditions, a limit of detection of 0.3 μg/l and a limit of quantification of 1.1 μg/l were obtained. The method showed good sensitivity and adequate selectivity and was satisfactorily applied to the determination of trace amounts of caffeine in urine, plasma and serumbelonging to subjectswith different sex, ages and habit of caffeine intake. Conclusions: Chemofiltration step eliminated the highly fluorescentmatrix, thus enabling and allowing CF quantification, in the presence of other methylxanthines. The proposed methodology represents an innovative application of the solid surface fluorescence using membrane filters modified with MWCNTs.