In the following circumstances, the Ph Tester must be to correction(1) solution temperature and correction of temperature have great changes;(2) leave solution time too long electrode;(3) change with the new composite electrode;(4) measurement concentrated acid (pH < 2)="" or="" strong ="" alkali="" (ph=""> 12) after;(5) measurement contains fluoride solution and acidity in pH < 7="" solution="" or="" thicker="" after="" organic="" solution.(6)="" correction,="" please="" will="" ph="" correction="" fluid="" in ="" 25="" ±="" 1="" ℃="" temperature="">
