Loss on drying (LOD)

LOD: Loss on drying. It is the expression of moisture content on a wet-weight basis. The loss of drying test is a method to measure the loss in weight of the sample when dried under the conditions specified in each monograph. This method is applied to determine the amount of water, all or a part of water of crystallization or volatile matter in the sample, which is removed during the drying. The description for example not more than 1% (1 gm, 105ยบ, 4 hours) in a monograph. On a wet-weight basis the water content of a material is calculated as a percentage of the wet solid. The water lost by evaporation is read directly from the percent LOD scale. It is assured that there are no other volatile materials present. LOD is calculated as follows:

W1 = Empty LOD bottle weight
W2 = Sample + LOD Bottle
W3 = Weight after drying

Loss on drying is the loss of weight expressed as percentage w/w resulting from water and volatile matter of any kind that can be driven off under specified conditions. The test is carried out on a well-mixed sample of the substance.

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