Many people are confused when it comes to understanding the difference between moisture content and Loss on Drying (LOD). To clarify this, please read the entire section in this post. Firstly, let’s discuss moisture analyzers. A moisture analyzer is used to determine the water content in a sample. The question then arises: How many types of moisture analyzers are used in the pharma industry to determine LOD, and what is the principle of a moisture analyzer? How to calculate moisture content and LOD? Let’s discuss them one by one.
Types of Moisture Analyzers
- IR moisture analyzer
- Halogen Moisture analyzer
IR analyzer: IR moisture analyzer is the equipment used to determine the moisture content of a sample using the loss on drying method. It consists of a weighing unit to measure the sample weight and a heating unit that uses IR (infrared) to heat the sample.
Halogen analyzer: A halogen analyzer emits Infra-Red radiation and radiates moisture that is present in the sample.
What is Moisture content?
Moisture content is the amount of water present in the sample.
Formula for % moisture content:
Principle of Moisture Analyzer:
The principle of moisture analyzer works on the thermos gravimetric method, which is also referred to as the “loss on drying” principle.
Loss on Drying (LOD) test:
The loss on drying test is designed to measure the amount of water and volatile substances present in a sample, expressed as w/w (weight by weight) when the sample is dried under specific conditions.
The formula for % LOD check:
Difference between moisture content and (LOD):
The Karl Fischer titration method is used to determine the moisture content in a sample, and the result only contains water. This means that the result does not include any other volatile content present in the sample.
To measure the drying loss, including all volatile materials (including water content and solvents), the sample is heated below its melting point in an oven at specific conditions (usually 105°C for 3 hours).