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Environmental fate & pathways

Henry's Law constant

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Reference
Endpoint:
Henry's law constant
Type of information:
experimental study
Adequacy of study:
key study
Study period:
22 November 2000 - 16 October 2002
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: A thesis describing the research conducted by a Ph.D. student at the Institute for Risk Assessment Sciences (IRAS), University of Utrecht (NL). No raw data available.
Reason / purpose:
reference to same study
Guideline:
other: described in thesis
Principles of method if other than guideline:
Henry's law constant was determined on the basis of equilibrium partitioning in a closed system of air and AHTN spike water. AHTN was extracted by SPME and analysed by Gas Chromatography with flame ionisation detection.
GLP compliance:
no
H:
37.1 Pa m³/mol
Temp.:
25 °C
Atm. press.:
1 atm

Henry's law constant for hexachlorobenzene was 121.2 to 128.8 Pa·m3/mol. According to the author, these values are within range of literature values, ranging from 49-172 Pa·m3/mol.

Conclusions:
The method was validated with hexachlorobenzene and Henry's law constant of AHTN was therefore accepted.
Executive summary:

Henry's law constant was determined on the basis of equilibrium partitioning in a closed system of air and AHTN spiked water.

AHTN dissolved in water was allowed to equilibrate with air in a closed bottle. Air and water were mixed for 2 minutes and left undisturbed at 25°C for 24h. AHTN was extracted by SPME and analysed by Gas Chromatography with flame ionisation detection. Prior to the analysis, the method was tested with hexachlorobenzene.

The Henry coefficient for AHTN was 37.1 Pa m3 -mol (Artola 2002).

Description of key information

The empirical determined value of Henry's law constant was taken forward in the calculations of predicted environmental calculations.

Key value for chemical safety assessment

Henry's law constant (H) (in Pa m³/mol):
37.1
at the temperature of:
25 °C

Additional information

Using a vapour pressure of 0.0682 Pa and a water solubility of 1.25 mg/l a Henry’s Law Constant of 14.1 Pa·m3/mol is calculated. EPISUITE (EPA), module HenryWin v3.20) predicted 4.3 Pa·m3/mol.

The Henry’s Law Constant was empirically determined by Artola (2002) at 37.1 Pa·m3/mol. This was based on equilibrium partitioning in a closed system using solid phase micro extraction. The value determined by experiment is regarded as the most reliable result. The value reported by Artola was used in the PEC calculations for the EU Risk Assessment Report of AHTN (ECB, May 2008).