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Physical & Chemical properties

Solubility in organic solvents / fat solubility

Administrative data

Endpoint:
solubility in organic solvents / fat solubility
Type of information:
experimental study
Adequacy of study:
key study
Study period:
09/Jul/2001 to 23/Aug/2001
Reliability:
3 (not reliable)
Rationale for reliability incl. deficiencies:
other: This study cannot be relied upon as the study fails to properly account for volatility of the test substance, potential for the formation of micro-emulsions, and does not utilize direct, target specific analytical methods.

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2001
Report Date:
2001

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
other: OECD guideline for testing of chemicals no. 116: "Fat solubility of solid and liquid substance", Adp May 12, 1981.EEC-Dir 84/449 EEC, Part A, Methods for the determination of physico-chemical prop, A.7: "Fat solubility", EEC Publication no.L251, Sept 1984
Deviations:
not specified
GLP compliance:
yes

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
- Name of test material (as cited in study report): T-7479
- Physical state: Clear colorless liquid
- Analytical purity: "Not indicated by the sponsor; treated as 100% pure"
- Stability under test conditions: No information
- Storage condition of test material: At room temperature in the dark.
- Other: Stability under storage conditions: Not indicated

Results and discussion

Solubility in organic solvents / fat solubility
Medium:
standard fat
Solubility:
24 g/kg solvent
Temp.:
37 °C
Test substance stable:
not determined
Details on results:
- Temperature effects: Not noted
- Examination of different polarities: Not noted
- Information on chemical stability: Not noted.
- Other:

This study is inconclusive for several reasons. It fails to properly characterize the testing vessels as open or closed. Chemical has a high vapor pressure (31.6 kPa), indicating that any headspace in a closed system or, if the system were completely open, concentrations of the test substance would quickly drop from the nominal concentrations. Additionally, visual observation and UV Vis spectrometry would not provide insight into material that is actually solubilized vs. microemulsified material. Because no direct analytical measurements were made, and for the above reasons, fat solubility cannot be determined from this study.

Any other information on results incl. tables

Study utilized a commercially available standard fat (HB 307; NATEC, Institut fur naturwissenschaftlichtechnische Dienste GmbH, Hamburg, Germany. An initial range finding test was conducted at 2.6 g/L, 10 g/L, 100 g/L and 1032 g/kg. Test vessels containing the mixtures of test substance and standard fat were stirred overnight (no set time indicated) on a magnetic stirring device in a 37 C water bath. A 50 mL blank liquefied fat sample was treated in the same way to serve as a reference. Utilizing visual inspection, it was determined the fat solubility was between 10 g/L and 100 g/L. No specific information is provided on the visual queues utilized. The definitive study utilized concentrations of 9.7 g/kg, 21 g/kg, 32 g/kg, 41 g/kg, and 53 g/kg. These were prepared by direct addition of weighed amounts of test substance to 25 mL of liquified standard fat at 37C, then diluting each to 50 mL with additional liquified standard fat. These solutions were then placed on a magnetic stirring device in a water bath at 37.0 +/- 0.5 C and stirred for 2 days. Visual observations were performed immediately after preparation, 44-45 hours after preparation, and 51-52 hours after preparation. It was noted that, "where necessary, the mixture was shaken well prior to observation". No criteria is given to describe when shaking was "necessary". No specific information is provided on the visual queues utilized.

Results of the range finding test
Nominal test
concentration
Test substance
observed in the
mixture
Fat solubility
1032 g/kg Yes < 1032 g/kg
100 g/L Yes < 100 g/L
10 g/L No > 10 g/L
2.6 g/L No

> 2.6 g/L

Absorbances for the test mixtures from the definitive study
Nominal test
concentration
g/kg
Absorbances [units]1
9.7 0.277 / 0.285
21 0.677 / 0.744
32 0.864 / 0.8322
41 0.884 / 0.8632
1. Duplicate measurements
2. Corrected for the elevated baseline.

Preparation of the test mixtures for the definitive study
Amount of test
substance [mg]
Total amount of
liquid fat [g]
Nominal
concentration [g/kg]
441.4 45.4 9.7
932.9 45.3 21
1417 44.9 32
1831 44.8 41
2340 44.4 53

Results of the definitive study
Nominal test
concentration
g/kg
Test substance
observed in the
mixture
Fat solubility
53 Yes < 53
41 Yes < 41
32 Yes < 32
21 No > 21
9.7 No > 9.7

Applicant's summary and conclusion

Conclusions:
While the study reports a fat solubility for CAS# 756-13-8 of 24 g/kg at 37.0 +/- 0.5 C, this value cannot be relied upon.
Executive summary:

The reported fat solubility for CAS# 756-13-8 at 37.0 +/- 0.5 C is 24 g/kg. This value cannot be relied upon as the study fails to properly account for volatility of CAS# 756-13-8, potential for the formation of micro-emulsions, and does not utilize direct, target specific analytical methods.