pH Meter Calibration: Distilled Water vs Boiled Water with EDTA

Regarding your question about calibrating a pH meter for the first time and whether you can use boiled water mixed with EDTA instead of distilled water:

As the staff correctly advised, you must use distilled water (or deionized water) for preparing the standard buffer solutions required for pH meter calibration.

Boiled water, even if mixed with EDTA, is not a suitable substitute. Boiled water may still contain dissolved minerals and impurities that can affect the pH and conductivity, leading to inaccurate calibration. EDTA is a chelating agent and would also interfere with the buffer solutions.

Accurate calibration relies on using standard pH buffer solutions (commonly pH 4.00, 7.00, and 10.00) prepared with high-purity water like distilled or deionized water. This ensures the buffer solutions have precise and stable pH values at a given temperature, which is critical for setting the meter's response correctly.

Using the proper calibration method with distilled water and standard buffer solutions is essential to ensure your pH meter provides accurate and reliable measurements for your formulations.