Simultaneous determination of lead and cadmium at a glassy carbon electrode modified with Langmuir-Blodgett film of p-tert-butylthiacalix[4]arene

A glassy carbon electrode (GCE) modified with a Langmuir-Blodgett (LB) film of p-tert-butylthiacalix[4]arene (TCA) has been investigated as a disposable sensor for measuring the trace levels of lead and cadmium. The possibility of determining lead and cadmium at trace levels was examined with differential pulse stripping voltammetry in the measurement step. The electrochemical response was characterized with respect to supporting electrolyte, pH of solution, accumulation time, accumulation potential, layers of the LB films, and possible interferences. Calibration plots were found to be linear in the range 2 x 10(-7) to 5 x 10(-5) mol l(-1) (Cd2+)and 1 x 10(-7) to 2.5 x 10(-5) Mol l(-1) (Pb2+); the detection limits were 2 x 10(-8) mol l(-1) (Cd2+) and 8 x 10(-9) mol l(-1) (Ph2+). Possible recognition mechanism was also discussed. From the analysis of real samples (river, lake and tap water) it can be concluded that the method is sensitive and reproducible in determining of these elements and can be used in the analysis of natural water samples. (c) 2006 Elsevier B.V. All rights reserved.