Cobalt detection using fluorescent dye layers

In this paper, we report the preliminary results regarding the use of fluorescent dye calcein (C30H26N2O13) as a sensor for the detection of cobalt levels in aqueous solutions. The sensor cell based on calcein is built by fixed-in layers by means of thermoplastic polyurethane (TPU) and adjusted to pH = 7. The layer shows a fluorescence emission in the range of λ = 545 nm to 570 nm when it is excited by optical fields at a wavelength centered at 465 nm. By the contact of different cobalt concentrations with the calcein layer structure, quenching of the fluorescence intensity is observed. The results indicate that the sensor exhibits a linear response of the fluorescence quenching related to the cobalt concentration level in the range of 10−5 to 10−3 mol/L. Additionally, the proposed sensor has a simple experimental set-up, low cost, and does not require additional complex instrumentation.