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

In this work, a new methodology based upon enhancement of rhodamine B fluorescent signal is pro-posed for the quantification of caffeine traces.Methods: Membrane filters treated with multiple wall carbon nanotubes were employed as solid support for de-termination step by solid surface fluorescence.Results: Experimental variables that influence the preconcentration step and fluorimetric sensitivity have beenoptimized using uni-variation assays, presenting linearity from 1.1 to 9.7 × 103 μg/l, with a correlation coeffi-cient 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 wereobtained. The method showed good sensitivity and adequate selectivity and was satisfactorily applied to the de-termination of trace amounts of caffeine in urine, plasma and serum belonging to subjects with different sex, agesand habit of caffeine intake.Conclusions: Chemofiltration step eliminated the highly fluorescent matrix, thus enabling and allowing CF quan-tification, in the presence of other methylxanthines. The proposed methodology represents an innovative appli-cation of the solid surface fluorescence using membrane filters modified with MWCNTs.