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Potentiometric Titration

Learn what is potentiometeric titration and how is it carried out using indicator electrode and a reference electrode.
A convenient and useful method of determining the equivalence point of a titration, i.e the point at which the stoichiometric analytical reaction is complete, results from the use of electrochemical measurements. If an indicator electrode, sensitive to the concentration of the chemical undergoing titrimetric reaction, and a reference electrode, whose potential is not sensitive to any dissolved chemical in solution, are immersed in the solution under examination to form a galvanic cell, the potential difference between the electrodes may be sensed by a simple potentiometer or electromic device and used to follow the course of the reaction. If a graph of the variation of potential difference is plotted as a function of the quantity of the titrant added, a sigmoid curve results with a rapidly changing portion in the vicinity of the equivalence point. The mid - point of this linear vertical portion or the inflection point may taken as the end - point of the titration.
In a titrimetric assay the end - point determination is an estimate of the reaction equivalence point. The validity of this estimate depends upon, among other factors, the nature of the solution being titirated and the concentration of the titrant. A blank correction is employed in titrimetric assays to enhance the reliability of the end - point determination. With potentiometric titrations the blank correction is usually negligible.

Related: Calibration of Automatic Potentiometric Titrator


Potentiometric Titration Types of Electrods
Table 1
The apparatus used comprises a voltmeter allowing readings to the nearest millivolt. The choice of the electrode system is governed by the nature of the titration. Table 1 summaries several acceptable electrode systems. Automatic titrators are commonly employed these days. Two types of instruments are available. In the first one addition of titrant is carried out automatically and the electrode potential differences during the course of titration are recorded as the expected sigmoid curve. In the second type, titrant addition is performed automatically until or preset potential or pH, representing the end - point, is reached when the addition of the titrant ceases.

Ankur Choudhary is India's first professional pharmaceutical blogger, author and founder of Pharmaceutical Guidelines, a widely-read pharmaceutical blog since 2008. Sign-up for the free email updates for your daily dose of pharmaceutical tips.
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1 comment:

srinivas srinu said... on 4/5/16 10:35

please provide the electrode maintainance of all the potentiometric titrations

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