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 Pb2+ 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 Pb2+ by changing its color from blue to pinkish purple in Tris buffer containing different concentration of Pb2+ at pH 7.0. The optode provided the response range of 3.16 × 10−8 to 5.00 × 10−5 mol L−1 Pb2+ with the detection limit of 2.49 × 10−8 mol L−1 in the batch system within the response time of 30 min. The dynamic range of 1.26 × 10−8 to 3.16 × 10−5 mol L−1 Pb2+ with detection limit of 8.97 × 10−9 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 Pb2+ over Na+, K+, Mg2+, Cd2+, Hg2+ and Ag+. It was successfully applied to determine Pb2+ in real water samples and the results were compared with well-established inductively coupled plasma optical emission spectrometry (ICP-OES). No significant different value (tcritical = 4.30 > texp = 1.00–3.42, n = 3 at 95% of confidence level) was found.