Karl-Fischer Titration

Introduction to Karl-Fischer Titration

Water content is an important factor in several industries, including pharmaceuticals, chemicals, and food and beverage. Excessive moisture has an impact on product stability, shelf life, and overall quality. Karl-Fischer Titration provides a reliable method for determining water content, assuring conformity with industry standards and regulations. The method is recommended because it is limited to water, unlike other techniques that may be impacted by volatile compounds or other interfering variables. MaTestLab is one of the leading testing service providers in the USA and Canada. We have a large network of testing laboratories in the USA.

Principle and Methodology of Karl-Fischer Titration

Karl Fischer titration is based on the oxidation reaction between iodine and sulfur dioxide. Water combines with iodine and sulfur dioxide to produce sulfur trioxide and hydrogen iodide. When all the water has been drunk, the process concludes. The chemical equation for the reaction of sulfur dioxide, iodine, and water (used during Karl Fischer’s titration) is shown below.

Water and iodine are consumed in the same proportion. After consuming all of the water, the titrator’s indicator electrode detects excess iodine by voltammetry. That indicates the end of the titration. To calculate the amount of water in a sample, use the concentration of iodine in the Karl Fisher titrating reagent (titer) and the amount consumed during the titration. 

In coulometric Karl Fischer, iodine is produced electrochemically in situ during titration, while water is quantified based on the total charge passed (Q), measured by current and time, using the relationship Q = 1 C (Coulomb) = 1 A x 1 s, where 1 mg H2 O = 10.72 C

Instrumentation

Karl-Fischer Titration has a titration cell, electrodes for detecting endpoints, a burette for controlled titrant dispensing, a generator electrode for electrochemical iodine generation, a stirrer for thorough mixing of reagent and sample, and a control unit for managing the titration process and calculating water content, depending on the method used. Double platinum electrodes are commonly used.

Applications of Karl-Fischer Titration

Karl Fischer titration is a redox reaction that uses water consumption to measure the amount of water in a sample. Due to its specificity, accuracy, and speed, it is the reference method for water determination. It is utilized in a variety of technological products, including polymers, oils, and gases. It is also used in pharmaceutical products, cosmetic goods, food and beverages, and industrial applications.