Table 2.

Summary of the methods for determination of “loss on drying” and “water” in European Pharmacopoeia and Chinese Pharmacopoeia

European Pharmacopoeia	Chinese Pharmacopoeia
Loss on drying
Dry the sample under the specified temperature to constant mass (Δma ≤ 0.5 mg) or for the prescribed time by one of the following procedures and calculate the difference in the mass of the sample before and after drying, expressed as a percentage (m/m):     In a desiccator     In vacuo     In an oven at a specified temperature	Place about 1 g or specified amount of sample in a tared, shallow weighing bottle and dry the sample under 105 °C until constant weight (Δm ≤ 0.3 mg) except as otherwise herein provided. Calculate the loss of mass expressed as per cent Test may also be done with desiccator with temperature control or vacuum
Water
Distillation with toluene (procedure similar to method 4 in Chinese Pharmacopoeia)	Method 1: Karl-Fischer’s titration Method 2: Drying in the oven (100–105 °C until Δm ≤ 5 mg) Method 3: Drying under reduced pressure (≤ 2.67 kPa at room temperature for 24 h) Method 4: Toluene distillation Method 5: Gas chromatography

^a Δm: the difference in the mass of the sample between two consecutive weighings