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Learn about Loss on Drying test, purpose, procedure, acceptable limits , case studies and FAQs
Loss On drying Test (LOD Test) of Pharmaceuticals: Why, How and At what level
The Loss on Drying Test, or LOD test in pharmaceuticals, is a fundamental quality control procedure used to measure the amount of volatile matter (mainly water) in a sample.The following is a complete breakdown of why, how, and at what level this test is conducted:
Requirement details:
Common Instruments: Oven dryer, Infrared/Halogen moisture balance
Common methods: Oven drying, Infrared/Halogen drying
Limits are stated in pharmacopoeial monographs (USP, Ph. Eur., etc.).
Conclusion
The Loss on Drying (LOD) test is a critical quality control measure in pharmaceutical manufacturing, used to determine the amount of moisture and volatile matter in drug substances, excipients, and finished products. Accurate LOD testing ensures product stability, efficacy, manufacturability, and compliance with regulatory standards. The method selected—whether gravimetric oven drying, infrared drying, or Karl Fischer titration—depends on the nature of the material and the required sensitivity. Acceptable moisture limits vary by substance and are defined in pharmacopoeial monographs. Maintaining LOD within specified limits is essential for ensuring the quality, safety, and shelf life of pharmaceutical products.
The LOD test measures the amount of water and volatile substances present in a pharmaceutical sample by drying it under specific conditions and recording the weight loss.
Why is the LOD test important in pharmaceuticals?
It helps ensure the quality, stability, and shelf life of drugs by controlling moisture content, which can impact chemical stability, microbial growth, and physical properties of the formulation.
How is the LOD test performed?
Typically, a weighed sample is dried in an oven at a specified temperature (usually 105°C) until a constant weight is achieved, then the percentage of weight loss is calculated.
What is the difference between LOD and water content?
LOD measures all volatile matter (including water), while water content (e.g., via Karl Fischer titration) specifically quantifies only water.
What are typical acceptable LOD limits for pharmaceutical substances?
LOD limits vary by material and are defined in pharmacopeial monographs—e.g., lactose monohydrate may have a limit of ≤5%, while APIs often require much lower limits (e.g., <1%)
Which methods are used to determine LOD?
The Gravimetric oven drying (standard method) and infrared or halogen moisture analysers (faster, for in-process testing) methods are used to perform LOD:
What factors affect LOD test results?
Temperature, drying time, sample type, air flow, and environmental humidity can all influence the accuracy and consistency of LOD measurements.
Can LOD be used for both raw materials and finished products?
es. LOD is performed on raw materials (e.g., APIs, excipients) and finished dosage forms to ensure consistency and compliance throughout the manufacturing process.
