A benchtop pH meter is an electronic instrument used to measure the acidity and alkalinity of liquid or semi-solid samples across many industries with applications in waste water, drinking water, food and beverage, chemical and pharmaceutical testing.
Typical benchtop pH meters consist of a measuring electrode, reference electrode, and a meter. The measuring electrode is hydrogen ion [H+] sensitive and measures pH as the sample surrounds the glass bulb at the end. A small voltage output varies with the concentration of the H+ ions in the sample and that is measured and displayed as pH units by the meter. A variety of benchtop pH meters are available with different combinations of measurement modes including pH, mV, ion, and conductivity.
Temperature compensation is an important factor as the pH electrode is temperature dependent. The millivolt (mV) output from the pH electrode will change in correlation to the change in temperature of the sample. This is as a result of a direct change in the H+ ion activity of the sample and ionization of compounds. Depending on the type of pH meter, temperature compensation can be available in a manual or automatic mode.