| 摘要 |
In an amperimetric measurement apparatus comprising an amperimetric cell (10) having a pair of electrodes (12, 14) arranged for contact with a solution, a potential difference is established between the electrodes and a corresponding electric current is conducted in a forward direction through a current path which includes the electrodes and the solution. An output corresponding to the current indicates the concentration of a solute in the solution. The electrical charge passing through the cell (10) in response to said potential difference is monitored by an integrator (40). The forward current is interrupted repeatedly and a reverse electric current is imposed on the cell during the interruptions of forward current. The magnitude and duration of the reverse current are regulated in response to the electrical charge flow corresponding to the forward current, so that the net flow of charge through the cell over a time period including an equal number of intervals of forward and reverse current intervals is substantially zero. Consequently, ionic contaminants, which tend to be plated onto cell electrodes as a result of the forward current are removed substantially completely by deplating, without the risk of producing inaccurate measurements by placing the cell in a reverse charging condition. <IMAGE> |
