A Novel Flow‐Through Planar Solid Contact Sensor for the Determination of Lead with Potentiometric Anionic Response

The construction and general performance characteristics of two poly(vinyl chloride) matrix chemical sensors for lead were described. These sensors were based on the use of ion association complexes of trihydroxoplumbate, Pb(OH)₃]^? and tetraiodoplumbate, PbI₄]^2?with cetylpyridinium chloride (CP) and iron(II)‐4,7‐bathophenanthroline Fe(bphen)₃]²⁺ as novel electroactive materials dispersed in o‐nitrophenyloctyl ether (o‐NPOE) plasticizer for ionometric sensor controls, respectively. The sensing membrane (3×5 mm) is immobilized on a wafer polyimide chip (size 13.5×3.5 mm) to offer a planar miniaturized design that could be easily used flow injection system. Under static modes of operation, the sensors revealed a near Nernstian response over a wide Pb²⁺ ion concentration range 7.9×10^?7 to 10^?4 and 3.2×10^?7 to 10^?4 mol L^?1 with detection limit of 100 and 45.5 ng mL^?1, respectively . In flow injection potentiometry, excellent reproducibility (RSD%=0.5%), fast response, high sensitivity, high sampling rate (50 sample h^?1) and stable baseline was observed in the presence of 5×10^?2 mol L^?1 NaOH and 10^?1 mol L^?1 KI as a carrier for CP]Pb(OH)₃] and Fe(bphen)₃]PbI₄] membrane based sensors, respectively. Validation of the assay method according to the quality assurance standards (range, within‐day repeatability, between‐day variability, standard deviation, accuracy, lower detection limit) reveals good performance characteristics and suggests application for routine determination of lead in industrial wastewaters and stack emissions of lead smelters. The results agree fairly well with data obtained by the standard atomic absorption methods.