Fabrication of a Sensor using Seed Lectin in Voltammetric Detection of Heavy Metals
This study made use of a seed lectin as biological component of a metal sensor. Red kidney bean (Phaseolus vulgaris) seeds that served as source of lectin, were extracted with Tris buffered saline (TBS, 0.01 M in 0.15 M NaCl pH 7.5) solution, followed by ammonium sulfate precipitation (0-90%) and gel chromatography using Sephadex G-150. Hemagglutination assay was used to determine the presence of lectin in the collected gel chromatography fractions. Positive fractions were pooled together and freeze-dried. The freeze dried sample was mixed with carbon powder and Nujol oil to form a paste, which was used to fabricate a sensor to detect different heavy metals in aqueous solutions by electrochemical methods like cyclic voltammetry (CV) and differential pulse anodic stripping voltammetry (DPASV). Among the 6 heavy metals tested, only lead ions showed current signal. Eight percent (8%) lectin modifier composition and 0.1 M HCl as supporting electrolyte gave the optimum and highest signal. Electrodes that were pre-soaked with human erythrocyte solution gave a higher signal for lead ions.
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