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Partition coefficient

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Reference
Endpoint:
partition coefficient
Type of information:
experimental study
Adequacy of study:
key study
Study period:
07 November 2018 to 04 December 2018
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to
Guideline:
OECD Guideline 107 (Partition Coefficient (n-octanol / water), Shake Flask Method)
Deviations:
no
Qualifier:
according to
Guideline:
EU Method A.8 (Partition Coefficient - Shake Flask Method)
Deviations:
no
GLP compliance:
yes (incl. certificate)
Type of method:
flask method
Partition coefficient type:
octanol-water
Specific details on test material used for the study:
Test item: Acid Orange 94 Refined
Alternative name: Disodium 5, 5’-[(1-methylethylidene)bis(4,1-phenyleneoxysulphonyl-2,1-phenyleneazo)]bis[6-aminonaphthalene-1-sulphonate]
CAS number: 70161-18-1
EC number: 274-354-1
Intended use: Industrial chemical
Appearance: Reddish brown crystals
Storage conditions: Room temperature (10 – 30C), in the dark
Lot number: 8009
Expiry/Retest date: 31 December 2019
Purity: 97%
Analytical method:
high-performance liquid chromatography
Key result
Type:
log Pow
Partition coefficient:
1.76
Temp.:
21.8 °C
pH:
>= 6.4 - <= 6.7
Details on results:
The chromatography was baseline corrected using the relevant matrix blank to remove the effect of the gradient profile to assist the integration of the test item peaks.
The lower result of the preliminary test was considered to be due to the inefficient back-extraction of the organic phase in to a portion of n-octanol saturated water. This was also performed for the definitive test, but when this inefficiency was concluded the organic phases were re-analysed without extraction. However, the preliminary result was considered adequate to help assess the test procedure for use in the definitive test.
Due to a preparation error, the matrices for the aqueous standards were not consistent. The standards used to quantify the aqueous samples had a solvent ratio of 70:30 v/v instead of the intended 50:50 v/v. Those used for the linearity had a ratio range of 51:49 v/v to 90:10 v/v. It was considered that this had no quantifiable impact on the test as their responses still produced a linearity plot which was comparable to the organic linearity.
Conclusions:
The partition coefficient of the test item has been determined to be 1.76 x 10-2 at 21.8 ± 0.5 °C, and a log10 Pow of -1.79.
Executive summary:

The Partition Coefficient (n-octanol/water) was determined using the shake flask method, designed to be compatible with Method A.8 Partition Coefficient of Commission Regulation (EC) No 440/2008 of 30 May 2008 and Method 107 of the OECD Guidelines for Testing of Chemicals, 27 July 1995, in accordance with GLP.

The partition coefficient of the test item has been determined to be 1.76 x 10-2 at 21.8 ± 0.5 °C, and a log10 Pow of -1.79.

Description of key information

The Partition Coefficient (n-octanol/water) was determined using the shake flask method, designed to be compatible with Method A.8 Partition Coefficient of Commission Regulation (EC) No 440/2008 of 30 May 2008 and Method 107 of the OECD Guidelines for Testing of Chemicals, 27 July 1995, in accordance with GLP.

The partition coefficient of the test item has been determined to be 1.76 x 10-2 at 21.8 ± 0.5 °C, and a log10 Pow of -1.79.

Key value for chemical safety assessment

Log Kow (Log Pow):
1.76
at the temperature of:
21.8 °C

Additional information