Why Is It Important to Calibrate a pH Meter and Its Electodes Against a Buffer?

Electrodes are calibrated using three buffer solutions with known pH.
••• Jupiterimages/Photos.com/Getty Images

Accurate pH measurements cannot be accomplished with a pH meter unless the meter has been calibrated against standardized buffer. Without a proper calibration the meter has no way to determine the pH value of the solution you are testing.

Baiscs of a pH meter

The pH meter has a membrane that allows H+ ions to pass though, which allows a current to flow, creating a voltage. The voltage is measured by the meter and you tell it which standard buffer it is in. The pH meter then compares the voltage of your unknown solutions to that of the buffers to determine the pH of your solution.

Standardized Buffers

Standardized buffers are usually colored solutions that are guaranteed to be at a particular pH. They can usually be obtained from the manufacturer of the pH meter. These buffers are critical to the correct operation of a pH meter.

To maintain accuracy

To make a calibration curve at least three standards are needed. Without the standardized pH buffer to calibrate the meter the results will be inaccurate and useless.

To avoid drift

Most pH meters, and electrodes in general, are known to drift from their calibrated settings. It is important to calibrate your pH meter regularly to ensure that you continue to get accurate results. Drift cannot be avoided. Calibrate regularly to maintain accuracy.

To account for differences

Using standardized buffers when calibrating also helps to prevent differences among samples. Proper standards can avoid such problems as ionic strength difference and other membrane-related problems.

Related Articles

How to Standardize a pH Meter
What Is the Standard Method for Calibration of a Conductivity...
PH Meter Versus PH Paper
Advantages of Using a pH Meter
How to Identify if a Solution Is Neutral, Base or Acidic
What Is a Conductivity Meter?
Potential Sources of Error Using pH Strips
How to Measure Conductivity in Liquid
How to Convert Conductivity to Concentration
Methods for Testing PH of Liquids
How to Calibrate a pH Meter
The Effect of Solution Concentration on Conductivity
How to Make a Citric Acid Buffer Solution
The Role of GTE in DNA Extraction
What Is the Difference Between Blue & Red Litmus Paper?
How to Measure Soil Pollution
What Is the Function of a Tris Buffer in DNA Extraction?
How to Estimate pH Levels Without Test Strips
What Is pH of Sodium Carbonate in Water?