Used for calibration of pH meters in the acidic range. Applied in analytical laboratories and research work. Used in food and beverage testing (acidic products). Employed in quality control processes.

Its main role is to provide a reliable and stable reference point for acidic pH measurements ensuring accuracy in laboratory and industrial testing.

A mildly acidic aqueous solution with a stable pH of 4.00 at 25 deg C. It is commonly prepared using weak acidsalt systems (such as potassium hydrogen phthalate) to maintain a consistent pH.