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Partition coefficient

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Endpoint:
partition coefficient
Type of information:
(Q)SAR
Adequacy of study:
weight of evidence
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: The quoted value is an estimate based on an internationally recognised modelling programme
Justification for type of information:
QSAR prediction: migrated from IUCLID 5.6
Qualifier:
according to
Guideline:
other: QSAR Calculation
Principles of method if other than guideline:
Quantitative Structural-Activity Relationship based upon chemical structure devised from the SMILES code drawn from a database of >40,000 chemicals (called PHYSPROP©) that is included in the EPI Suite™ software
GLP compliance:
no
Other quality assurance:
other: ISO 9001
Type of method:
other: QSAR
Partition coefficient type:
octanol-water
Key result
Type:
log Pow
Partition coefficient:
18.05
Temp.:
25 °C
Remarks on result:
other: pH not dertermined as the result is from QSAR calculation.
Conclusions:
The partition coefficient of the substance is considered to be 18.05 at 25C based on a QSAR driven by the EPI Suite v4.0
Executive summary:

Removal of mineral oil is not possible without degrading the chemical struture of the substance. It was therefore considered acceptable to create a weight of evidence approach based upon Quantitative Structural-Activity Relationship (QSAR). The QSAR model of choice was the EPI Suite v4.0 published by the United States Environmental Protection Agency, which has estimated the partition coefficient to be 18.05 at 25oC

Endpoint:
partition coefficient
Type of information:
experimental study
Adequacy of study:
supporting study
Study period:
Between 19 April 2011 and 01 December 2011
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: see 'Remark'
Remarks:
Study conducted in compliance with agreed protocols/ Current OECD Guidelines and to GLP standards, with no or minor deviations from standard test guidelines and/or minor methodological deficiencies, which do not affect the quality of the relevant results.
Reason / purpose:
reference to same study
Qualifier:
according to
Guideline:
OECD Guideline 107 (Partition Coefficient (n-octanol / water), Shake Flask Method)
Deviations:
no
Principles of method if other than guideline:
Because the shake-flask and HPLC methods are not ideally suited to surface active substances such as the test material, an estimation of the partition coefficient was calculated using the solubilities in octanol and water using a procedure designed to be compatable with Methods 107m and 117 of the OECD Guidelines. An assessment of the partition coefficient was made based on the approximate solubilities of the test item in n-octanol by visual assessment and the water solubility result (see IUCLID 4.8 Water solubility Harlan Project No. 41100980). The estimate of the partition coefficient was calculated using the equation: Pow = Solubility of the test item in n-octanol/Solubility of the test item in water.
GLP compliance:
yes (incl. certificate)
Type of method:
other: Approximate solubilities
Partition coefficient type:
octanol-water
Analytical method:
other: visual for octanol; HPLC for water
Key result
Type:
log Pow
Partition coefficient:
> 5.47
Temp.:
20 °C
pH:
9.1
Remarks on result:
other: See IUCLID Section 4.8 Harlan No. 41100980 showing pH of water
Details on results:
Approximate solubility in n-octanol: >500 g/1
Solubility in water: ≤1.69E-3 g/1
Approximate Pow: >2.95E5
Log10 Pow: >5.47





Conclusions:
The partition coefficient of the test item has been estimated to be greater than 2.95E5,
log10 Pow >5.47.
Substance is the sulphonate salt in mineral oil and provides information on the product but not the instrinsic properties of the sulphonate

Executive summary:

Because the shake-flask and HPLC methods are not ideally suited to surface active substances such as the test material, an estimation of the partition coefficient was calculated using the solubilities in octanol and water using a procedure designed to be compatable with Methods 107m and 117 of the OECD Guidelines. An assessment of the partition coefficient was made based on the approximate solubilities of the test item in n-octanol by visual assessment and the water solubility result (see IUCLID 4.8 Water solubility Harlan Project No. 41100980). The estimate of the partition coefficient was calculated using the equation: Pow = Solubility of the test item in n-octanol/Solubility of the test item in water. Because neither the shake flask or HPLC methods are ideally suited to surface active materials, the partition coefficient was based on approximate solubilities. Because the similar test substance OS12202AE (Harlan Project No. 41100982) when prepared in water saturated n-octanol emulsified and did separate with time, it was considered that the same would happen with this test material. It was recognized that the shake-flask method would be limited to measuring a partition coefficient at approximately log10 Pow 2 to 4 as the result would be limited by the stock solution concentration required to avoid emulsification and analytical sensitivity.  Having a limit on the stock solution concentration does not allow for high partition coefficients to be measured with the shake-flask method. Also, the HPLC method could be invalidated by secondary interactions of the negatively charged organic sulphonate component which would need to be analysed at a pH far below the limits of the test (pH 2 to 9) and HPLC column to have it in an un-ionised form. A definitive value for the solubility of the test material could not be determined visually in octanol, but with a solution of greater than 50%. (w/w), in the region of 500 g/l, it was clearly evident that the test material was highly soluble in octanol. The partition coefficient of the test item was estimated to be greater than 2.95E5, log10 Pow >5.47.

Endpoint:
partition coefficient
Type of information:
experimental study
Adequacy of study:
supporting study
Study period:
Between 19 April 2011 and 01 December 2011
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: see 'Remark'
Remarks:
Study conducted in compliance with agreed protocols/ Current OECD Guidelines and to GLP standards, with no or minor deviations from standard test guidelines and/or minor methodological deficiencies, which do not affect the quality of the relevant results.
Reason / purpose:
reference to same study
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 107 (Partition Coefficient (n-octanol / water), Shake Flask Method)
Deviations:
no
Principles of method if other than guideline:
Because the shake-flask and HPLC methods are not ideally suited to surface active substances such as the test material, these methods were determined not to be appropriatedan estimation of the partition coefficient was calculated using the solubilities in octanol and water using a procedure designed to be compatable with Methods 107m and 117 of the OECD Guidelines. An assessment of the partition coefficient was made based on the approximate solubilities of the test item in n-octanol by visual assessment and the water solubility result (see IUCLID 4.8 Water solubility Harlan Project No. 41100980). The estimate of the partition coefficient was calculated using the equation: Pow = Solubility of the test item in n-octanol/Solubility of the test item in water.
GLP compliance:
yes (incl. certificate)
Type of method:
other: approximate solubilities
Partition coefficient type:
octanol-water
Analytical method:
other: Visual for ocatanol; HPLC for water
Key result
Type:
log Pow
Partition coefficient:
> 6.65
Temp.:
20 °C
pH:
6.3
Details on results:
The partition coefficient of the test item has been estimated to be greater than 4.43E6 ,
log10 Pow, >6.65.
Conclusions:
The partition coefficient of the test item has been estimated to be greater than 4.43E6 ,
log10 Pow, >6.65.
Substance is the sulphonate salt in mineral oil and provides information on the product but not the instrinsic properties of the sulphonate
Executive summary:

The estimation was calculated using the solubility in octanol and water. The procedure used was designed to be compatible with Methods 107 and 117 of the OECD Guidelines for Testing of Chemicals. An assessment of the partition coefficient was made based on the approximate solubilities of the test item in n-octanol by visual assessment and the water solubility result (see IUCLID 4.8 Water solubility Harlan Project No. 41100981). The estimate of the partition coefficient was calculated using the equation: Pow = Solubility of the test item in n-octanol/Solubility of the test item in water. Because neither the shake flask or HPLC methods are ideally suited to surface active materials, the partition coefficient was based on approximate solubilities. Because the similar test substance OS12202AE (Harlan Project No. 41100982) when prepared in water saturated n-octanol emulsified and did separate with time, it was considered that the same would happen with this test material. It was recognized that the shake-flask method would be limited to measuring a partition coefficient at approximately log10 Pow 2 to 4 as the result would be limited by the stock solution concentration required to avoid emulsification and analytical sensitivity.  Having a limit on the stock solution concentration does not allow for high partition coefficients to be measured with the shake-flask method. Also, the HPLC method could be invalidated by secondary interactions of the negatively charged organic sulphonate component which would need to be analysed at a pH far below the limits of the test (pH 2 to 9) and HPLC column to have it in an un-ionised form. A definitive values for solubility of this test item in octanol could not be determined visually above 500 g/l where it was clearly highly soluble. However, the water solubility test showed that the test item was essentially insoluble. The partition coefficient of the test item has been estimated to be greater than 4.43E6 , log10 Pow, >6.65.

Endpoint:
partition coefficient
Type of information:
experimental study
Adequacy of study:
supporting study
Study period:
Between 19 April 2011 and 01 December 2011
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: see 'Remark'
Remarks:
Study conducted in compliance with agreed protocols/ Current OECD Guidelines and to GLP standards, with no or minor deviations from standard test guidelines and/or minor methodological deficiencies, which do not affect the quality of the relevant results.
Reason / purpose:
reference to same study
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 107 (Partition Coefficient (n-octanol / water), Shake Flask Method)
Deviations:
no
Principles of method if other than guideline:
The estimation was calculated using the solubility in octanol and water. The procedure used was designed to be compatible with Methods 107 and 117 of the OECD Guidelines for Testing of Chemicals. An assessment of the partition coefficient was made based on the approximate solubilities of the test item in n-octanol by visual assessment and the water solubility result (see IUCLID 4.8 Water solubility Harlan Project No. 41100982). The estimate of the partition coefficient was calculated using the equation: Pow = Solubility of the test item in n-octanol/Solubility of the test item in water.
GLP compliance:
yes (incl. certificate)
Type of method:
other: approximate solubilites
Partition coefficient type:
octanol-water
Analytical method:
other: visual for octanol; HPLC for water
Key result
Type:
log Pow
Partition coefficient:
> 4.46
Temp.:
20 °C
pH:
8.1
Details on results:
The partition coefficient of the test item has been estimated to be greater than 2.85 x 104 ,
log10 Pow, >4.46.
Conclusions:
The partition coefficient of the test item has been estimated to be greater than 2.85E4 ,
log10 Pow, >4.46.
Substance is the sulphonate salt in mineral oil and provides information on the product but not the instrinsic properties of the sulphonate
Executive summary:

The estimation was calculated using the solubility in octanol and water. The procedure used was designed to be compatible with Methods 107 and 117 of the OECD Guidelines for Testing of Chemicals. An assessment of the partition coefficient was made based on the approximate solubilities of the test item in n-octanol by visual assessment and the water solubility result (see IUCLID 4.8 Water solubility Harlan Project No. 41100982). The estimate of the partition coefficient was calculated using the equation: Pow = Solubility of the test item in n-octanol/Solubility of the test item in water. Because neither the shake flask or HPLC methods are ideally suited to surface active materials, the partition coefficient was based on approximate solubilities. At approximately 100 mg/1 of test item in water saturated n-octanol, the n-octanol and water phases emulsified and did separate with time. I was recognized that theshake-flask method would be limited to measuring a partition coefficient at approximately log10 Pow 2 to 4 as the result would be limited by the stock solution concentration required to avoid emulsification and analytical sensitivity.  Having a limit on the stock solution concentration does not allow for high partition coefficients to be measured with the shake-flask method. Also, the HPLC method could be invalidated by secondary interactions of the negatively charged organic sulphonate component which would need to be analysed at a pH far below the limits of the test (pH 2 to 9) and HPLC column to have it in an un-ionised form. It was considered that the water solubility measured was somewhat higher than the true value.  Bearing this in mind, as the estimate uses this water solubility value in the calculation, the partition coefficient estimate would be somewhat greater than that calculated. The partition coefficient of the test item has been estimated to be greater than 2.85E4 , log10 Pow, >4.46.

Description of key information

The registered substance is produced, supplied and marketed in the presence of a liquid mineral oil solvent.  Removal of this solvent is expected to cause a change in the equilibrium of the chemical structure of the alkaryl benzene sulfonates resulting in a degradation of the chemical structure to a structure that is not representative of the substance being placed on the market in the EU.  It is, in consequence, not possible to undertake any study of the registered substance in the absence of the solvent.  This is further compounded by the fact that the presence of the mineral oil solvent changes the physical state of the registered substance from solid to liquid and will therefore have a considerable effect on the result of any test conducted on the substance in solvent.  It is therefore considered justifiable to omit any study, but the results from QSAR are included to allow for a weight of evidence approach.

Key value for chemical safety assessment

Log Kow (Log Pow):
22.12
at the temperature of:
25 °C

Additional information

The alkaryl benzene sulfonates are a group of inter-related substances of similar structure typically consisting of a benzene ring with a sulphonic acid which may be present as the free acid or metal substituted salt and one or more long chain alkyl groups that may vary in length and the degree of branching. The alkaryl benzene sulfonates are produced in base oils from petroleum streams and display similar chemistry, characterised typically as relatively high melting glass like substances, in the absence of the mineral oil, extremely low water solubility and very high partition coefficient.

The presence of mineral oil, however, alters the physical appearance from solid to liquid, so it is not technically feasible to conduct a study to measure the partition coefficient of the substance. Estimations have, therefore, been undertaken using the EPIWIN Modelling Program. To allow for a weight of evidence approach estimations have been made for all suitable molecular variations in the series alkaryl benzene sulfonates. For the purpose of additional relaibility, the result given above is a mean average melting point value calculated by QSAR across the series of structurally related substances.

To further support this approach a QSAR Prediction Reporting Format (QPRF) is attached to justify the QSAR system as adequate for estimating the value for the purposes of REACH registration