Lab and analysis
Loss on drying (LOD)
Definition
The percentage of mass lost when a sample is dried under set conditions, covering water and other volatile matter.
Loss on drying is measured by heating a sample at a defined temperature, sometimes under vacuum, until its weight is constant. It is simple and common in pharmacopoeia monographs.
Because it includes any volatile matter, LOD can be higher than the water content measured by Karl Fischer. Assay results are often reported on the dried basis, which uses the LOD result.