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Environmental fate & pathways

Adsorption / desorption

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Description of key information

For OPP a moderate adsorption potential is expected (Koc = 247).

Key value for chemical safety assessment

Koc at 20 °C:

Additional information

To assess the adsorption/desorption behavior of OPP (CAS-No. 90-43-7) two guideline studies are available. In the first study, which was carried out according to OECD guideline 106 and in GLP compliance, the adsorption/desorption behavior of OPP in four different soils, which comprised two times clay loam, a sandy loam and a sandy silt loam were tested. In all soils a non-linear relationship between the concentration in solution and the amount adsorbed to the soil was observed, with values for 1/n ranging from 0.78 to 0.87. Additionally, there was no significant correlation between pH and adsorption for the investigated soils. The Koc values obtained ranged from 252 to 393 mL/g (mean = 347 mL/g). No degradation product was observed during ad- and desorption by HPLC in the supernatant of the selected soils. Therefore it can be concluded that no significant degradation of OPP occurred during the duration of the study (Oddy and Jacob, 2005).

These Koc values are supported by another study estimated using High Performance Liquid Chromatography (HPLC). The test was performed according to OECD guideline 121 (Proposal for New Guideline, 2001). Six reference standards of known Koc values and OPP were analysed on a HPLC system. The Koc value for OPP was estimated by interpolation from the reference substance regression line. The estimated Koc value for OPP is 346.7 (Erstling, 2001).

In conclusion, it can be assumed that the adsorption potential of OPP is moderate.

[LogKoc: 2.54]

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