The term “solvent-free” signifies that the calculation shall be corrected for the presence of known solvents as determined using the methods described in Residual Solvents〈467〉 unless a test for limit of organic solvents is provided in the monograph.
The term “previously dried” without qualification signifies that the substance shall be dried as directed under Loss on Drying 〈731〉 or Water Determination 〈921〉 (gravimetric determination).
Where drying in vacuum over a desiccant is directed, a vacuum desiccator, a vacuum drying pistol, or other suitable vacuum drying apparatus shall be used.