Determination of Total Solids

The term 'total solids' is applied to the residue obtained when the prescribed amount of the preparation is dried to constant weight under the conditions specified here.

Apparatus

Shallow, flat-bottomed, flanged dishes, about 75 mm in diameter and about 25 mm deep, made of nickel or other suitable metal of high heat conductivity and which is not affected by boiling water.

Method

Weigh accurately or measure an accurate quantity of the substance under examination stated in the individual monograph, place in a tared dish, evaporate at an as low temperature as possible until the solvent is removed and heat on a water-bath until the residue is apparently dry. Transfer to an oven and dry to constant weight at 105°, unless otherwise stated in the monograph. Owing to the hygroscopic nature of certain residues, it may be necessary to use dishes provided with well-fitting covers and to cool in a desiccator.