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Physical & Chemical properties

Vapour pressure

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Description of key information

Key result for CAS # 756-13-8:
Vapor pressure: 40.4 kPa (303 mm Hg) at 25°C
Key result for PFPA (degradation product), CAS# 422-64-0:
Vapor pressure: 53 hPa at 20 °C (equivalent to handbook value)

Key value for chemical safety assessment

Additional information

Discussion for CAS# 756-13-8:

Vapor pressure CAS# 756-13-8 was assessed in four studies. In the key study, CAS# 756-13-8 had a measured vapor pressure of 40.4 kPa (303 mm Hg) at 25°C. In the first supporting study, CAS# 756-13-8 had a measured vapor pressure of 40.5 kPa (303.5 mm Hg) at 25°C and 32.8 kPa (246.1 mm Hg) at 20°C. In the second supporting study, CAS# 756-13-8 had a measured vapor pressure of 40.3 kPa (302 mm Hg) at 24.7°C and of 32.8 kPa (246 mm Hg) at 20.3°C. In the third supporting study, CAS# 756-13-8 had an extrapolated vapor pressure of 31.6 kPa (237 mm Hg) at 20°C using a static method at thermal equilibrium. The key study utilizes a dynamic method, but it is unknown whether the study followed a guideline or GLP criteria. The study measured equilibrium points above and below the normal boiling point. It is therefore classified as reliable with restrictions. The first supporting study also utilizes a dynamic method and it produced nearly identical results to the key study. The study used standard instrumentation according to method ASTM E-1719-97, in a dynamic method as permitted by TG104§8, yet GLP compliance is not known. It is classified as reliable with restrictions. The second supporting study, while not GLP-compliant and sparsely detailed in its report, used essentially the same instrumentation and it too produced results nearly identical to the key study. This near-identity is especially significant as the tests covered a different temperature-vapor pressure range and the supporting studies had either been reported over one year after the key study or by a separate laboratory. The determination of the vapor pressure in the third supporting study was based on EEC-Directive 92/69EEC, A.4 and on OECD Guideline no. 104, and was GLP-compliant. It is therefore considered reliable without restrictions, relevant and valid to this endpoint. Three separate dynamic method study reports by two different laboratories at three different time periods have determined near identical results whereas the static method produces a slightly different result. It is the sponsor’s judgment that the dynamic method results provide the most accurate assessment of CAS# 756-13-8 vapor pressure.

Discussion for PFPA (degradation product), CAS# 422-64-0:

Vapor pressure of PFPA was reported from two sources. The key result was reported by the vendor, Sigma-Aldrich, as part of PFPA product information. The reported vapor pressure at 20°C was 53 hPa. In a previous chemical registration dossier, a QSAR value of 5.8 kPa (58 hPa) at 25 °C was reported. This value is based on simulation using obsolescent software (EpiSuite v.3.12) and is provided here solely to acknowledge the prior submission. It is not considered further.

 

The method by which the vapor pressure reported on the vendor MSDS was determined is not available. However, the value is part of a dataset on this chemical compiled by Sigma-Aldrich and retrieved from an on-line database of safety data sheets created and provided by the vendor which can be readily accessed by the public. It is equivalent to handbook data in its reliability.