If you are talking about the granules before compression this is based on the trial and error basis. It depends on material and this has to be studied during lab scale batches by compressing the tablets in various LOD levels to identify the limit.
if you want to determine LOD of granules then you can go with the IR moisture balance generally, but if the compound is thermolabile then you have to choose KF or coloumetric method for moisture determination, in my view the prior one is most common method used in pharma industry .
Sir I am not asking how to determine the LOD. Secondly KF is used to determine water content not LOD. My question is how to determine the %LOD of the granules before compression.