Selective fluorimetric detection of cadmium in a microfluidic device

A microfluidic device equipped with a fluorimetric detection has been developed for the flow injection detection of cadmium, a very toxic metal. The fluorescent sensor, Rhod-5N, is a water-soluble commercial dye whose fluorescence is increased in presence of cadmium. A detection limit of 0.45 mu g L-1 has been determined in MOPS buffer at pH 7. Special attention was paid to the interference of other metal ions. The interference of Pb2+ was circumvented by solid phase adsorption (SPE) on aminopropyl silica. Langmuir analysis of the adsorption isotherms has shown a better affinity of this functionalized silica towards Pb2+. After optimization of both pH and flow rate of the analyte through the SPE minicolumn, cadmium could be determined even in presence of lead at a concentration 10 times larger. (C) 2012 Elsevier B.V. All rights reserved.