Bulk optode sensors for batch and flow-through determinations of lead ion in water samples

A sensitive optode consisting of highly lead-selective ionophore (Lead IV), proton-selective chromoionophore (ETH 5294) and lipophilic anionic sites (KTpClPB) in plasticized polyvinyl chloride (PVC) membrane was fabricated. The optode membranes were used for determination of Pb(2+) by absorption spectrophotometry in batch and flow-through systems. The influence parameters such as pH, type of buffer solution, response time and concentration of regenerating solution were optimized. The membrane responded to Pb(2+) by changing its color from blue to pinkish purple in Tris buffer containing different concentration of Pb(2+) at pH 7.0. The optode provided the response range of 3.16x10(-8) to 5.00x10(-5) mol L(-1) Pb(2+) with the detection limit of 2.49x10(-8) mol L(-1) in the batch system within the response time of 30 min. The dynamic range of 1.26x10(-8) to 3.16x10(-5) mol L(-1) Pb(2+) with detection limit of 8.97x10(-9) mol L(-1) were obtained in the flow-through system within the response time of 15 min. Moreover, the proposed optode sensors showed good selectivity towards Pb(2+) over Na(+), K(+), Mg(2+), Cd(2+), Hg(2+) and Ag(+). It was successfully applied to determine Pb(2+) in real water samples and the results were compared with well-established inductively coupled plasma optical emission spectrometry (ICP-OES). No significant different value (t(critical)=4.30>t(exp)=1.00-3.42, n=3 at 95% of confidence level) was found.