Irreversible optical sensor for mercury determination based on tetraarylborate decomposition

A new optical disposable sensor to determine mercury is presented. The procedure uses a polyester sheet with a sensing area composed of plasticized PVC that incorporates a tetraarylborate salt as Hg(II) selective recognition reagent and a porphyrin proton-selective fluoroionophore as the optical transducer. The sensing scheme is based on the decomposition of tetraarylborate anion induced by Hg(II) taken by the membrane which compels the deprotonation of the porphyrin, recovering its fluorescence. The fluorescence increases after 15 min contact with Hg(II) at pH 2.4 which makes it possible to determine Hg(II) up to 25 μg L−1 with an intermembrane reproducibility of 6.5% as R.S.D. The disposable sensor presents good selectivity to Hg(II) over other metal ions. The response mechanism is discussed and the effect of different experimental variables is reported.