Authors: Francisco Pena-Pereira, Nerea Capón, Inmaculada de la Calle, I. Lavilla, C. Bendicho
Journal: Sensors and Actuators, B: Chemical, 299, 126979, 2019
Poly(vinylpyrrolidone)-supported copper nanoclusters (CuNCs) are employed in the present work as luminescent probes for iodide determination in water samples. The method involves the combination of two miniaturized analytical systems, namely nanoparticle-enhanced liquid-phase microextraction and microvolume fluorospectrometry. The proposed method is based on the in situ generation of iodine and trapping of the evolved volatile into a CuNCs-containing aqueous microdrop, thus leading to fluorescence quenching. The fluorescence quenching mechanism for iodine sensing can be presumably ascribed to a ‘sphere of action’ static quenching model. Instrumental conditions, as well as a number of experimental parameters affecting extractant phase composition, iodine generation conditions and mass transfer of the volatile, have been evaluated. An outstanding enrichment factor of ca. 1100 was achieved under optimal conditions, yielding limits of detection and quantification of 1.0 ng/mL and 3.4 ng/mL, respectively. The repeatability, expressed as relative standard deviation, was found to be 7.4% (N = 7). The method was validated against a certified reference material and successfully applied to the analysis of different water samples. Furthermore, paper-based analytical devices containing CuNCs have been evaluated for the non-instrumental sensing of iodine generated in situ, showing promise as an inexpensive and portable alternative for iodide determination.