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Partition coefficient

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

partition coefficient

Data waiving:

study technically not feasible

Justification for data waiving:

the study does not need to be conducted because the substance is inorganic

Reference 2

Endpoint:

partition coefficient

Type of information:

experimental study

Adequacy of study:

supporting study

Study period:

20 March 2017 to 01 August 2017

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 117 (Partition Coefficient (n-octanol / water), HPLC Method)

Deviations:

yes

Remarks:

guideline demonstrated to be not applicable

Qualifier:

according to guideline

Guideline:

EU Method A.8 (Partition Coefficient - HPLC Method)

Deviations:

yes

Remarks:

guideline demonstrated to be not applicable

GLP compliance:

yes (incl. QA statement)

Type of method:

HPLC method

Partition coefficient type:

octanol-water

Analytical method:

high-performance liquid chromatography

Remarks on result:

other: guideline demonstrated to be not applicable

Details on results:

RESULTS
- Results demonstrated that the active ingredient precipitated out of water saturated octanol stock solution.
- The filtered stock had an observed Tyndall beam effect which suggested some fine precipitate still remained; if this had been filtered out then the filtered results may have been even lower.
- Furthermore, the stock solution was observed again after being left undisturbed for two weeks; the solution was cloudy with a large amount of an off-white precipitate. This suggested even more had dropped out of solution.

TABLE 16 – MEAN RESULTS FROM QUADRUPLE UNFILTERED STOCK AND FILTERED STOCK

Solution	Concentration calcium (mg/L)	Concentration boron (mg/L)
Unfiltered stock	12.7	2.07
Filtered stock	8.49	1.50
Matrix banks	≤ 0.69	≤ 0.02

Conclusions:

The partition coefficient test by the flask-shake method was not applicable. As the test item was inorganic based, preparing a stock solution in octanol saturated water was not feasible either.

Executive summary:

GUIDELINE

The partition coefficient of the test item was not determined, using a procedure designed to be compatible with Method A.8 Partition Coefficient of Commission Regulation (EC) No 440/2008 of 30 May 2008 and Method 117 of the OECD Guidelines for Testing of Chemicals, 13 April 2004, as the test guideline was demonstrated to be not applicable.

METHODS

The partition coefficient of inorganic substances, as is the active ingredient of the test item, is not usually required. However, the Sponsor requested the endpoint to be determined, as in this case, the inorganic active was suspended in an organic medium. This may then have significantly affected its bioaccumulation potential. The flask-shake method was therefore attempted. The HPLC method to determine partition coefficient would not be applicable for pure inorganic substances or those in an organic medium.

A stock solution of the test item was prepared at approximately 4 g/L in water saturated octanol. This was observed to be a clear brown solution but with a Tyndall beam effect after ultrasonication. However, it was decided to still validate the microwave digestion procedure which removes the octanol and creates an acidic aqueous media so that analysis by Inductively-Coupled Plasma-Mass Spectrometry could be performed. The stock solution was left overnight to allow any precipitation to settle out. Observing the solution it had become cloudier and was filtered through a 0.45 μm membrane. The filtrate was a clear, very light brown solution with a strong Tyndall beam effect and was treated similarly by microwave digestion and analysed.

RESULTS

Results demonstrated that the active ingredient precipitated out of water saturated octanol stock solution. The filtered stock had an observed Tyndall beam effect which suggested some fine precipitate still remained; if this had been filtered out then the filtered results may have been even lower. Furthermore, the stock solution was observed again after being left undisturbed for two weeks; the solution was cloudy with a large amount of an off-white precipitate. This suggested even more had dropped out of solution.

CONCLUSION

The partition coefficient test by the flask-shake method was not applicable. As the test item was inorganic based, preparing a stock solution in octanol saturated water was not feasible either.

Description of key information

The study does not need to be conducted because the substance is inorganic.

Additional information

GUIDELINE

The partition coefficient of the test item was not determined, using a procedure designed to be compatible with Method A.8 Partition Coefficient of Commission Regulation (EC) No 440/2008 of 30 May 2008 and Method 117 of the OECD Guidelines for Testing of Chemicals, 13 April 2004, as the test guideline was demonstrated to be not applicable.

METHODS

The partition coefficient of inorganic substances, as is the active ingredient of the test item, is not usually required. However, the Sponsor requested the endpoint to be determined, as in this case, the inorganic active was suspended in an organic medium. This may then have significantly affected its bioaccumulation potential. The flask-shake method was therefore attempted. The HPLC method to determine partition coefficient would not be applicable for pure inorganic substances or those in an organic medium.

A stock solution of the test item was prepared at approximately 4 g/L in water saturated octanol. This was observed to be a clear brown solution but with a Tyndall beam effect after ultrasonication. However, it was decided to still validate the microwave digestion procedure which removes the octanol and creates an acidic aqueous media so that analysis by Inductively-Coupled Plasma-Mass Spectrometry could be performed. The stock solution was left overnight to allow any precipitation to settle out. Observing the solution it had become cloudier and was filtered through a 0.45 μm membrane. The filtrate was a clear, very light brown solution with a strong Tyndall beam effect and was treated similarly by microwave digestion and analysed.

RESULTS

Results demonstrated that the active ingredient precipitated out of water saturated octanol stock solution. The filtered stock had an observed Tyndall beam effect which suggested some fine precipitate still remained; if this had been filtered out then the filtered results may have been even lower. Furthermore, the stock solution was observed again after being left undisturbed for two weeks; the solution was cloudy with a large amount of an off-white precipitate. This suggested even more had dropped out of solution.

CONCLUSION

The partition coefficient test by the flask-shake method was not applicable. As the test item was inorganic based, preparing a stock solution in octanol saturated water was not feasible either.