Chemical name. Hard fat.
Description. A white, brittle, unctuous mass; almost odourless.
Solubility. Practically insoluble in water; freely soluble in ether R; slightly soluble in ethanol (~750 g/l) TS.
Category. Suppository base.
Storage. Hard fat should be kept in a well-closed container, protected from light, and stored at a temperature not exceeding 5 °C below the melting range.
Additional information. On warming, hard fat melts to a colourless to slightly yellow liquid. On shaking the molten material with an equal quantity of hot water, forms a white emulsion.
Note: For certain applications, it may be necessary to comply with more restrictive specifications.
Definition. Hard fat is a mixture of mono-, di- and triglyceride esters of higher saturated fatty acids (C10H20O2 to C18H36O2).
Melting range. Cool the charged tube at a temperature below 10 °C for 24 hours; 33-40 °C.
Acid value. Not more than 0.5.
Hydroxyl value. Not more than 50.
Iodine value. Not more than 3.
Peroxide value. Not more than 6.
Saponification value. Use 2.0 g; 220-250.
Unsaponifiable matter. Use 5 g; not more than 1.0%.
Ash. Not more than 0.5 mg/g.
Alkaline impurities. Dissolve 2 g in a mixture of 1.5 ml of ethanol (~750 g/l) TS and 3 ml of ether R. Add 0.05 ml of bromophenol blue/ethanol TS; not more than 0.15 ml of hydrochloric acid (0.01 mol/l) VS is required to change the colour of the solution to yellow.
Decomposition products. Shake 1 g with 1 ml of hydrochloric acid (~420 g/l) TS for 1 minute, add 1 ml of resorcinol/toluene TS, shake for 5 seconds, and allow to stand for 5 minutes; the aqueous layer is not more intensely coloured than 1 ml of a mixture of 0.4 ml of potassium permanganate (0.002 mol/l) VS and 9.6 ml of water.