In order to measure the pH, you need either a pH indicator or a pH meter of which the pH meter is usually more accurate (especially if you buy a good one).
pH Meters
pH Measurement Tips
To measure the pH, make sure you have the pH electrode in a vertical position.
Gently stir the buffer solution when adjusting the pH.
Never put the electrode in solutions containing SDS.
Periodically calibrate the electrode with at least two calibration solutions.
Store the pH electrode in solution, keep the diaphragm wet and make sure that there is always electrolyte solution inside the electrode.
Wash clean the pH electrode with distilled water after usage and carefully tamp the electrode with cleaning paper.
Caution: the pH of most solutions is temperature-dependent:
At 5°C the pH of a 0.05 M Tris solution is 8.07
At 25°C the pH of a 0.05 M Tris solution is 7.50
At 37°C the pH of a 0.05 M Tris solution is 7.22
