Analytical Sciences

Scanning Electrode Quartz Crystal Analysis. Back-Scanning Mode and Application to Electrochemical Measurements

Tetsu TATSUMA * , Kyoko MORI and Noboru OYAMA *

Department of Applied Chemistry, Faculty of Technology, Tokyo University of Agriculture and Technology, Nakacho, Koganei, Tokyo 184-8588, Japan

Scanning electrode quartz crystal analysis (SEQCA) in the back-scanning mode is described. Although qualitative mapping of the mass distribution on a quartz plate is possible in air or non-conducting liquids by means of SEQCA in the fore-scanning mode, mapping is difficult in an electrolyte solution (e.g. 10 mM NaCl), which behaves as an electrode due to its ionic conductivity. On the other hand, because the back-scanning mode does not suffer from the ionic conductivity of a solution, mapping is possible even in a 0.1 M NaCl solution. This technique is applied to electrochemical measurements. An electrode on a quartz plate is partially masked, and polypyrrole is deposited on the bare region by electropolymerization from an electrolyte solution containing pyrrole. The deposited polypyrrole can be located in the electrolyte solution by means of SEQCA in the back-scanning mode. (Keywords: Scanning electrode quartz crystal microbalance, two-dimensional mapping of mass distribution, electrodeposition)

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