Flow-through fluorescence-based optosensor for the screening of zinc in drinking water.

A single and rapid solid surface fluorescence-based flow-through optosensor has been developed for the screening of trace amounts of Zn(II) in drinking water samples. The proposed method is based on the transient immobilization of the target species: the complex formed between Zn(II) and the fluorogenic reagent p-(tosylamino)quinoline (p-TAQ) on an appropriate solid support (C(18) silica gel). The fluorescence of the complex was continuously monitored at an emission wavelength of 495 nm upon excitation at 377 nm. The instrumental, chemical and flow-injection variables were carefully investigated and optimized. The sensor was calibrated over the range of 5 - 125 ng mL(-1), obtaining a limit of detection of 0.9 ng mL(-1), a RSD of 1.8%, with a sampling frequency of 20 h(-1). The proposed method was successfully applied to different drinking water samples with recoveries between 98 and 104%.