We use the following methods to calibrate the pH

1.       Rinse the electrode with the deionized water and blot dry using a piece of tissue (Shur Wipes or Kim wipes are available in the labs).      
2.       Place the electrode in the solution of pH 7 buffer.
3.       Allow the display to stabilize and then set the display to read 7.
4.       Follow the above steps 3-4 times to check the accuracy.