The pH value of a sample can be determined by two methods, the electrometric method, and the colorimetric method. Adequately precise values can be determined using the electrometric method, but special equipment is required. The colorimetric method is easy and desires inexpensive mechanisms, and is enough precise for common work. However, it is subject to intervention by turbidity, color, free chlorine, high saline content, and different oxidants and reducing agents.
The pH indicator of any solution can be determined using an indicator solution or indicator paper, but the obtained results are not accurate since +-1 is the built error of pH. For precise measurement, a pH meter is used.
Several indicator electrodes are available for determining pH, Glass electrodes are widely used electrodes and many types of glass are used to make sensitive glass bulbs. Lithia glass is appropriate on the whole range of pH 0.00 to 14.00. The standard buffer is recommended to calibrate the pH meter. (pH 07.00, pH 04.00 and pH 9.20). i.e., determine the asymmetric potential. Then the pH can be read directly from the panel of pH meter of the unknown solution. The pH meter includes a glass and a reference electrode, LCD/LED display and temperature compensated.
Glass electrode: The sensor electrode is a special glass bulb in which HCL has a certain concentration and has a buffering chloride solution in contact with an inner reference electrode.
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