Fatty acids, C8-14 (even numbered) methyl-2-sulfoethyl esters, sodium salts

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 has a high surface activity

Reference 2

Endpoint:

partition coefficient

Type of information:

(Q)SAR

Adequacy of study:

key study

Study period:

May 2018

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

results derived from a (Q)SAR model, with limited documentation / justification, but validity of model and reliability of prediction considered adequate based on a generally acknowledged source

Justification for type of information:

Results derived from a valid (Q)SAR model and falling into its applicability domain, with limited documentation / justification

Qualifier:

no guideline followed

Principles of method if other than guideline:

The US EPA EPI Suite v4.00 KOWWIN v1.68 model uses a "fragment constant" methodology to predict logarithm octanol-water partition coefficient (log Kow) property data.  In a "fragment constant" method, a structure is divided into fragments (atom or larger functional groups) and coefficient values of each fragment or group are summed together to yield the log Kow estimate.   KOWWIN’s methodology is known as an Atom/Fragment Contribution (AFC) method.  Coefficients for individual fragments and groups were derived by multiple regression of 2447 reliably measured log Kow values.  KOWWIN’s "reductionist" fragment constant methodology (i.e. derivation via multiple regression) differs from the "constructionist" fragment constant methodology of Hansch and Leo (1979) that is available in the CLOGP Program (Daylight, 1995).  See the Meylan and Howard (1995) journal article for a more complete description of KOWWIN’s methodology.

To estimate log Kow, the KOWWIN v1.68 model initially separates a molecule into distinct atom/fragments.  In general, each non-hydrogen atom (e.g. carbon, nitrogen, oxygen, sulfur, etc.) in a structure is a "core" for a fragment; the exact fragment is determined by what is connected to the atom.  Several functional groups are treated as core "atoms"; these include carbonyl (C=O), thiocarbonyl (C=S), nitro (-NO2), nitrate (ONO2), cyano (-C/N), and isothiocyanate (-N=C=S).  Connections to each core "atom" are either general or specific; specific connections take precedence over general connections.

GLP compliance:

no

Type of method:

other: calculation

Partition coefficient type:

octanol-water

Type:

log Pow

Partition coefficient:

>= -1.13 - <= 1.81

Temp.:

20 °C

pH:

7

Conclusions:

SCMI Log Kow was estimated to be in the range -1.13 - 1.81

Executive summary:

According to EU method A.8 (2008), shake flask (OECD 107) and HPLC (OECD 117) experimen methods are "not applicable to surface active materials (for which a calculated value or an estimate based on the individual n-octanol and water solubilities should be provided)". Experimental data concerning the solubility of SCMI in n-octanol is not available so in the absence of this a log Kow value has been predicted using the US EPA EPI Suite v4.00 KOWWIN v1.68 software package.

SMILES strings for the C8 and C14 fatty acid methyl isethionate consituents was used as input to the model. These constituents represent the extreme chain lengths present in the active SCMI.

SCMI Log Kow was estimated to be in the range -1.13 - 1.81

Description of key information

Sodium Cocoyl Methyl Isethionate (SCMI) is an Anionic Surface Acting Agent. This therefore affects the results of the Octanol-Water Partition Coefficient test, due to the emulsion that forms at the partition interface. Surface acting agents have the ability of altering the surface or interfacial energies of two immiscible phases, thus skewing the results of testing. According to OECD Testing Guidelines for Test Method 117 Partition Coefficient (n-octanol/water), High Performance Liquid Chromatography Method isn’t applicable for surface-active agents. According to OECD Testing Guidelines for Test Method 107, the Shake Flask method is impossible to use with surface-active agents. According to OECD Testing Guidelines for Test Method 123, Partition Coefficient (1-Octanol/Water), Slow Stirring method is not applicable for substances that display significant interfacial activity. So, as with the Shake Flask method and due to the properties of SCMI, coupled with its foaming capabilities it would impossible to separate the two immiscible solvents at the interface to obtain reliable results

According to EU method A.8 (2008), shake flask (OECD 107) and HPLC (OECD 117) experimen methods are "not applicable to surface active materials (for which a calculated value or an estimate based on the individual n-octanol and water solubilities should be provided)". Experimental data concerning the solubility of SCMI in n-octanol is not available so in the absence of this a log Kow value has been predicted using the US EPA EPI Suite v4.00 KOWWIN v1.68 software package.

SMILES strings for the C8 and C14 fatty acid methyl isethionate consituents was used as input to the model. These constituents represent the extreme chain lengths present in the active SCMI.

SCMI Log Kow was estimated to be in the range -1.13 - 1.81. Although these firgures are theoretical and essentially meaningless for surface active substances, a log Kow value of 0.83 (for the major SLMI constituent of SCMI) is selected as the key value for CSA

Key value for chemical safety assessment

Log Kow (Log Pow):

0.83

at the temperature of:

20 °C