Characterization of a new uranyl selective bulk optode; utilizing synergistic effect in optical sensor

A new optical sensor is fabricated for determination of uranyl ion. The optode membrane is prepared by incorporation of 1-(2-pyridylazo)-2-naphtol (PAN), tri-n-octyl phosphine oxide (TOPO) and sodium tetraphenylborate (Na-TPB) to the plasticized poly(vinyl chloride) membrane. In the proposed optode, PAN functions as both ionophore and chromoionophore while TOPO has synergistic effect on the complexation of uranyl ion by PAN. The membrane composition is optimized to yield optimum performance. The linear range of the proposed optode is from 1.00 × 10−6 up to 1.50 × 10−4 M of UO22+ with a detection limit of 8.20 × 10−7 M. The proposed optode is selective to the uranyl ion in the presence of 1,2-cyclohexylene dinitrilotetraacetic acid (CyDTA). The sensor can be regenerated by exposure to a solution of thiosalicylic acid (0.05 M, pH 10) and it was applied to the determination of UO22+ spiked in tap water samples.