What Is The Difference Between KF And LOD
In pharmaceutical quality control, there are different methods to determine the water content or moisture content of the sample. i.e. 1. Karl Fischer titration method 2. The loss on Drying Method (LOD) is mostly used. Likewise halogen moisture analyzer (HMA), Thermogravimetric method (TGA) also there.
Let’s understand the difference between KF and LOD:
Water content by Karl Fischer Titration:
Karl Fischer Titration only measures the water content present in the sample.
A Karl Fischer titration is a very specific technique that can find and measure only water, including water from crystallization and surface absorption.
During the process, iodine and water are reacted with sulfur dioxide, a base, and alcohol. As mentioned, the water-iodine reaction depends on the availability of water and because water is the only source of reagent, the reagent titer reflects the amount of water used up in the reaction.
In addition to causing a color change, the KF reagent also causes an electrometric change that is detectable by two platinum electrodes when it is fully reacted with the water. A KF titration measures total water without being affected by the presence of volatile solvents.
Water content by Loss on Drying:
Loss-on-Drying measures the total change in weight of a sample as a result of drying.
It is based on the principle of drying a sample of the product and comparing its weight before and after it has been dried. Differences in weight are indicative of the moisture content within a product. Different methods can be used for this, such as drying ovens, infrared balances, and infrared lamps. Whatever the case may be, there are specific conditions for drying.
As a result of evaporation, the difference in weight after drying is the moisture content after losing all evaporated matter. During testing, the temperature and time controls are the sole determinants of the repeatability and accuracy of this method.
A challenging aspect of this method is that it measures all of the moisture lost from the sample, including not just water, but also other volatile components present in the sample (like residual solvents) or created by polymerization or degradation.
The Important difference between KF and LOD is, KF determines only moisture content in the sample and LOD determines weight loss of sample due to sample drying including volatile impurities.
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