• British Pharmacopoeia Volume III
  • Formulated Preparations: Specific Monographs

Cetomacrogol Emulsifying Wax

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General Notices

Non-ionic Emulsifying Wax

Action and use

Emulsifying agent.

Definition

Cetostearyl Alcohol

800 g

Macrogol Cetostearyl Ether (22)

200 g

Extemporaneous preparation

The following directions apply.

Melt together and stir until cold.

Characteristics

A white or almost white, waxy solid or flakes melting when heated to a clear almost colourless liquid.

Practically insoluble in water, producing an emulsion; moderately soluble in ethanol (96%); partly soluble in ether.

Identification

A. Incinerate at a temperature not exceeding 450° until free from carbon and cool. The residue is negligible (distinction from Emulsifying Wax).

B. Complies with the test for Sulfated ash.

Tests
Acid value

Not more than 0.5, Appendix X B.

Refractive index

At 60°, 1.435 to 1.439, Appendix V E.

Solidifying point

45° to 53°, Appendix V B, using the following modifications. Place in the inner test tube sufficient of the melted substance to fill the tube to a depth of about 50 mm. Stir the substance gently and steadily, without scraping the wall of the tube, while the tube and its contents are allowed to cool. The temperature at which the level of the mercury in the thermometer remains stationary for a short time is regarded as the solidifying point.

Alkalinity

Dissolve 10 g in 10 mL of water and 10 mL of ethanol (96%). Not more than 0.5 mL of 0.1m hydrochloric acid VS is required for neutralisation using phenolphthalein solution R1 as indicator.

Hydroxyl value

175 to 192, Appendix X D. Use 3.5 g.

Saponification value

Not more than 2.0, Appendix X G. Use 20 g.

Sulfated ash

Not more than 0.1%, Appendix IX A.