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Solubility in organic solvents / fat solubility

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solubility in organic solvents / fat solubility
Type of information:
experimental study
Adequacy of study:
key study
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
according to
other: OECD Guideline 105 (Water Solubility)
: n-ocatnol was used instead of water
GLP compliance:
Key result
> 400 g/L
20 °C
Test substance stable:

Data obtained for the first set of samples indicated a steady increase in test substance concentration over the 72-hour equilibration period. Thus, a second set of samples was established and equilibrated for a minimum time of 72 h and a maximum of 120 h. Similarly, the results demonstrated an increasing solubility of test substance in n-octanol over the equilibration periods. Replicate variability for some sampling intervals is noted to be high with percent relative error reaching as much as 31%. While the measured concentration of the test material continued to rise through 120 h of testing, the measured concentration after 72 h reached the treatment level introduced in the experiment. Results at 120 h represent approximately 200% of the treatment concentration. The cause of these results is unknown. Instrumental response remained generally constant across the two experiments. Quality control samples were near 100% of the prepared concentration. Systemic bias cannot explain the high measured concentrations observed in test samples.

The technique used to measure the test material, gel permeation chromatography, provides separation based on molecular weight and structure. As possible reasons for the inconsistent analytical results the author discussed the formation of some quaternary structure with n-octanol on the idea of a conjugate or a change of the molecule caused by n-octanol. The result of either of these hypothetical events would lend itself to a change in the detector response as compared with calibration standards. Quality control samples were not exposed to n-octanol for the length of time or at the same temperatures as test samples.

Description of key information

> 400 g/L at 20°C (OECD 105, flask method)

Key value for chemical safety assessment

Additional information