Perpustakaan Digital ITB

ABSTRACT: Silica modified electrode has been developed for stripping voltametric analysis of Hg", Pb2+ and Cue+ ions. Adsorption of Hg2+ ion on the surface of the electrode reaches a maximum at pH 5.5. Therefore, for Hg2+ ion analysis deposition was conducted at pH 5.5 while stripping process was conducted in 0.1 M HNO3 solution. Linear calibration curve of Hg2+was found in the concentration range between 1.0 '11 0-'M and 5.0 ' 10-5 M. The detection limit (3s) of Hg2+ ion analysis is 8.5 '10-' M (16 ppb). On the other hand, for the analysis of Pb2+ and Cue+ ions, deposition and stripping processes were conducted in 0.1 M HNO3 solution. Linear calibration curve of Pb2+was found in the concentration range between 6 ppb and 10 ppm, while for Cue+ linear calibration curve was found in the concentration range between 3 ppb and 10 ppm. Detection limit (3s) for Pb2+ and Cue+ analysis are 2 ppb and 1 ppb, respectively. The electrode has been applied for the measurement of lead in petroleum. The results show good consistency with those obtained using atomic absorption spectrophotometry (AAS) method. The electrode has also been applied for the measurement of Pb 2+ and Cue+ ions in three river water samples and one seawater sample. The concentration of Pb 2+ and Cue+ ions in all sample analysed was in ppb level so that the results could no yet be confirm using AAS methods due to the high detection limit of the later method.