Measurements of Alkalinity in Seawater by Potentiometric Titration (CAT#: STEM-ACT-0104-CJ)

When a pair of electrodes is placed in a sample solution or analyte, the potential difference between the two electrodes is indicated by the addition of a titrant or by a change in ion concentration. These two electrodes are named as reference electrode and indicator electrode. A reference electrode is an electrode that maintains its potential and remains stable when immersed in a sample solution. The indicator electrode is the electrode that responds to the change in potential of the analyte solution. A salt bridge is used to prevent the analyte from interfering with the reference electrode. The electric potential or overall potential difference can be calculated by the equation Ecell = Eind - Eref + Ej.

Marine Chemistry

Potentiometric titration consists of measuring the potential of the indicator electrode relative to the reference electrode as a function of titrant volume. In this titration method, the cell potential (measured in millivolts or pH) needs to be measured and recorded after each addition of titrant. When the end point is approached, the titrant is started to be added in very small amounts. In potentiometric titration, the most direct and commonly used method of endpoint detection is to plot a graph between cell potential and titrant volume. The midpoint of the steeply rising portion of the graph or curve is visually detected and serves as the endpoint.

Translated with www.DeepL.com/Translator (free version)

• Sample: Blood; Biological Fluids; Water and wastewater; Soil; Plant material; Feed and fertilizer; Food & More
• Equipment: Potentiometric Titrator

1. It is a low-cost titration method.
2. A little amount of materials is required.
3. It does not require the use of indicators.
4. Because no color indications are used, the titration findings are accurate.
5. it is extremely pH-sensitive.
6. It takes much longer than titration using indicators.
7. Sensitive in ionic strength.