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The main components DIPE and DSBE have a high Henry’s law constant at 20 °C: the measured value for DIPE is 173 Pa m³/mol or 0.0709 (dimensionless) [1]. The estimated value for DSBE is 500 – 1000 Pa m³/mol (Bond / Group Method) or 0.2 – 0.4 (dimensionless) using the HENRYWIN (v3.20) routine of Episuite [2]. According to the TGD IR & CSA R7a (2008, p.191), chemicals with H values around 100 Pa m³/mol are considered to volatilise rapidly.

TBA has a lower Henry’s law constant of 0.905 Pa m³/mol [3] and SBA a Henry’s law constant of 0.906 Pa m³/mol [4], similar to TBA. Both are expected to volatilise from surface water, but at a much slower rate.


[1] Arp PH & Schmidt TC, Air-Water Transfer of MTBE, Its Degradation Products, and Alternative Fuel Oxygenates: The Role of Temperature, Environ Sci Technol. 2004 Oct 15; 38(20); 5405 - 12

[2] EPI SuiteTM (2000 - 2008). Estimation Program Interface Suite, version 4.0. Syracuse Research Corporation, Syracuse, NY, USA.

[3] U. S. Environmental Protection Agency December, 2009, Hazard Characterization Document, Sponsored Chemical: t-Butyl Alcohol (CASRN 75-65-0)

[4] Snider JR, Dawson; J Geophys Res 90: 3797 - 3805 (1985)