| 摘要 |
PROBLEM TO BE SOLVED: To provide a device which can eliminate interferential influence gener ated when an electric conductivity electrode and a pH electrode are immersed in the same specimen with extreme reasonableness and can conduct pH measure ment and conductivity measurement accurately. SOLUTION: One 2 of two signal lines connected with a conductivity electrode 1 is connected with a conductivity-voltage conversion circuit 4 which measures the current flowing into the conductivity electrode 1. With the other signal line 3, the output side of a non-inverting operational amplifier 7 is connected through the first switch 6, and the second switch 8 to be put on or off simultaneously with the first switch 6 is installed between the inverted input terminal 7a of the operational amplifier 7 and the other signal line 3, and the reference potential 9 is connected with the non-inverted input terminal 7b of the operational amplifier 7. |
