Petrolatum

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Petrolatum is also known as yellow soft paraffi n. It is an inert material obtained from petroleum, which contains branched and unbranched hydrocarbons. It is available as soft oily material and appears pale yellow to yellow in color. Various grades of petrolatum are commercially available with varying physical properties. All these grades are generally insoluble in water and possess emollient properties. Concentrations up to 30% are used in creams. Petrolatum shows phase transitions on heating to about 35 ° C. As it possesses a higher coeffi cient of thermal expansion, prolonged heating is avoided during processing. The presence of minor impurities can oxidize petrolatum and discolor the product. Antioxidants are therefore added to prevent such physical changes in preparations during storage. Butylated hydroxyanisole, butylated hydroxytoluene, or α – tocopherol is generally incorporated as an antioxidant in petrolatum products. In addition, use of well – closed, airtight, light – resistant containers and storage in a cool and dry place improve stability of preparations. Minor quantities of polycyclic aromatic hydrocarbon impurities in petrolatum sometimes cause hypersensitivity reactions. Substituting yellow soft paraffi n with white soft paraffi n reduces such reactions

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