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Physical & Chemical properties

Water solubility

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Endpoint:
water solubility
Data waiving:
study technically not feasible
Justification for data waiving:
other:
Endpoint:
water solubility
Type of information:
experimental study
Adequacy of study:
supporting study
Study period:
2000-10-31 to 2001-06-26
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: GLP guideline study for the investigation on the acute toxic effects to D. magna with additional experimental data regarding the potential water solubility of neodecanoic acid, a degradation product of 1-methyl-1-phenylethyl peroxyneodecanoate.
Reason / purpose:
reference to same study
Qualifier:
no guideline followed
Principles of method if other than guideline:
Analytical determination of the concentration of neodecanoic acid - the degradation product of the peroxide 1-methyl-1-phenylethyl peroxyneodecanoate - at nominal peroxide concentrations of 0, 30.3, 40.8, 55, 74.9, and 99.7 mg/L by means of HPLC/MS.
GLP compliance:
yes (incl. certificate)
Type of method:
other: HPLC/MS
Key result
Water solubility:
>= 41.11 mg/L
Conc. based on:
other: degradation product neodecanoic acid
Remarks:
concentration determined via internal standard (lauric acid) and expressed as lauric acid equivalents
Loading of aqueous phase:
99.7 mg/L
Incubation duration:
66 h
Temp.:
19.5 °C
Remarks on result:
other: loading of aqueous phase refers to nominal peroxide concentration
Conclusions:
The water solubility of neodecanoic acid, the degradation product of 1-methyl-1-phenylethyl peroxyneodecanoate, is at least 41.1 mg/L at 19.5 °C.
Executive summary:

1-methyl-1-phenylethyl peroxyneodecanoate is not stable in aqueous solutions at temperatures ≥ +10 °C (= SADT). Therefore, an analytical determination of the water solubility of the peroxide is technically not possible.

Thus, the decomposition product neodecanoic acid is the relevant molecule for the risk assessment.

Within the scope of acute toxicity testing to Daphnia magna according to OECD guideline 202, 1-methyl-1-phenylethyl peroxyneodecanoate (71.5 % in isododecane) was applied to test solutions at nominal concentrations of 0 (control), 3.9, 7.5, 16.0, 33.0 and 70.4 mg/L.

Actual concentrations of 1-methyl-1-phenylethyl peroxyneodecanoate and of the decomposition product neodecanoic acid were measured by HPLC/MS. Concentrations of 1 -methyl-1 -phenylethyl peroxyneodecanoate were below the LOD of 70 µg/L already at the start of the test (t= 0 h). The concentration of neodecanoic acid was stable during the total test duration of 48 h. The maximum measured concentration of neodecanoic acid from test solutions with the highest nominal 1 -methyl-1 -phenylethyl peroxyneodecanoate loading of 99.7 mg/L was 41.11 mg/L. Therefore, it is concluded that the water solubility of neodecanoic acid is at least 41.11 mg/L (at 19.5 °C).

Description of key information

Determination of the water solubility of 1-methyl-1-phenylethyl peroxyneodecanoate according to OECD guideline 105 is technically not possible because the substance decomposes during testing (SADT +10 °C).

Thus, the decomposition product neodecanoic acid is the relevant molecule for the risk assessment.

Within the scope of toxicity testing according to OECD guideline 202, actual concentrations of 1-methyl-1-phenylethyl peroxyneodecanoate (71.5 % in isododecane) and neodecanoic acid were measured at start (t= 0 h) and end of the test (t= 48 h) by means of HPLC/MS. While expectedly 1-methyl-1-phenylethyl peroxyneodecanoate was not present in the test solutions already at the start of the test, the maximum measured concentration of neodecanoic acid from test solutions with the highest nominal loading of 99.7 mg 1-methyl-1-phenylethyl peroxyneodecanoate per litre was 41.11 mg/L. Therefore, it is concluded that the water solubility of neodecanoic acid is at least 41.11 mg/L (at 19.5 °C).

As a value for water solubility is required for exposure calculations, the value of 41.11 mg/L for the decomposition product neodecanoic acid is included as key value for chemical safety assessment.

Key value for chemical safety assessment

Water solubility:
41.11 mg/L
at the temperature of:
19.5 °C

Additional information