Under what circumstances can the acid-base concentration meter be recalibrated
(1) When there is a large difference between the solution temperature and the calibration temperature;
⑵The electrode is exposed to the air for too long, such as more than half an hour;
(3) The positioning or slope regulator is misoperated;
(4) After measuring the solution of overacid (pH<2) or overalkali (pH>12);
(5) After changing the electrodes;
⑹When the pH value of the measured solution is not in the middle of the solution selected during the two-point calibration, and it is far away from 7pH.
