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Vapour pressure

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Description of key information

The volatility of zinc bis[12-hydroxyoctadecanoate] is considered to be negligible.

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Additional information

The vapour pressure of a substance is defined as the saturation pressure above a solid or liquid substance. In EU method A.4, seven different measuring methods are listed for the measurement of the vapour pressure of solids and liquids. However, the vapour pressure does not need to be measured due to technical reasons if calculations indicate that the value is significantly less than 10-5 Pa. Zinc bis[12-hydroxyoctadecanoate] is a solid substance (salt of an organic acid and an inorganic cation) with a melting point of 150°C. In view of this, the volatility of this substance can therefore be safely assumed to be negligible, i.e. below the level of significance (10-5 Pa). For purposes of comparison, the HSDB lists for the organic acid moiety a vapour pressure of 5.7x10-6 Pa (4.28x10-8 mm Hg) at 25°C for stearic acid (Daubert and Danner, 1989). In consideration of the inorganic “salt” nature of this compound, it can therefore be anticipated that the vapour pressure of zinc bis[12-hydroxyoctadecanoate] is well below the value for the organic acid, and thus negligible. Therefore, in accordance with Annex XI - sections 1 and 2 of Regulation (EC) No 1907/2006, testing does not need to be conducted for technical as well as for scientific reasons.

[Daubert, T.E., R.P. Danner. Physical and Thermodynamic Properties of Pure Chemicals Data Compilation. Washington, D.C.: Taylor and Francis, 1989.] **PEER REVIEWED** in Hazardous Substances Data Bank via TOXNET at http://toxnet.nlm.nov