Strontium oxalate

Partition coefficient

Link to relevant study record(s)

Reference

Endpoint:

partition coefficient

Type of information:

(Q)SAR

Adequacy of study:

weight of evidence

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

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

Justification for type of information:

This endpoint study record is part of a Weight of Evidence approach. QSAR may be used in estimating the LogKow of the organic part, the oxalate and allows to fulfil the information requirements as further explained in the provided endpoint summary.

QSAR INFORMATIONS : Quantitative Structure Activity Relationships (QSAR) are theoretical models that can be used to predict in a qualitative or quantitative manner the physico-chemical, toxicological, ecotoxicological and environmental fate properties of compounds from a knowledge of their chemical structure.

1. SOFTWARE : EPI Suite

2. MODEL (incl. version number) : EPIWEB 4.11 Kowwin Version 1.68 (september 2010)

3. SMILES OR OTHER IDENTIFIERS USED AS INPUT FOR THE MODEL :
SMILES of the substance O=C1C(=O)O[Sr]O1
Name : Strontium oxalate
CAS : 814-95-9

4. SCIENTIFIC VALIDITY OF THE (Q)SAR MODEL
According to the guidance R.7a - version 5 - December 2016, "When no experimental data of high quality are available, or if experimental methods are known to be unreliable, valid (Q)SARs for log Kow may be used e.g. in a weight-of-evidence approach."
No formal QMRF assessment of the model is currently available, however, the user's guide describes all the information.
- Defined endpoint: Partition coefficient
- Methodology : KOWWIN uses a "fragment constant" methodology to predict log P. 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 P 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 P 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 P, KOWWIN 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.

5. APPLICABILITY DOMAIN
No formal QMRF assessment of the model is currently available, however, the user's guide describes all the information.

- Descriptor domain: organic chemical
QSAR may be used in estimating the LogKow of the organic part (but not applicable to the ion pair).

- Structural and mechanistic domains:
Training Set Molecular Weights: Minimum MW: 18.02 Maximum MW: 719.92 Average MW: 199.98 Appendix D of the KOWWIN Help gives the maximum number of fragments that occur in any individual compound of the training set.
- Similarity with analogues in the training set: The KOWWIN training and validation datasets can be downloaded from the Internet at http://esc.syrres.com/interkow/KowwinData.htm

Qualifier:

according to guideline

Guideline:

other: Epi Suite v1.68

Version / remarks:

KOWWIN’s methodology is known as an Atom/Fragment Contribution (AFC) method.
see Meylan, W.M. and P.H. Howard. 1995. Atom/fragment contribution method for estimating octanol-water partition coefficients. J. Pharm. Sci. 84: 83-92.

GLP compliance:

not specified

Type of method:

other: QSAR model

Partition coefficient type:

octanol-water

Specific details on test material used for the study:

The substance is a mono-constituent substance; the prediction is done on the constituent.

Type:

log Pow

Partition coefficient:

-0.17

Remarks on result:

other: QSAR (KOWWIN) with strontium oxalate. Sr2+ ion cannot be represented in the model.

Remarks:

Temperature and pH value are not specified by the QSAR model.

Conclusions:

The partition coefficient (log Pow) of the test item (strontium oxalate) was estimated to be -0.17 with (Q)SAR model EPI Suite software tool.

Executive summary:

The partition coefficient was estimated using the (Q)SAR model EPI Suite v1.68. This is a valid model for this substance which falls into its applicability domain.

The partition coefficient (log Pow) of the test item (strontium oxalate) was estimated to be -0.17.

Description of key information

The partition coefficient of the test item (strontium oxalate) was estimated using the (Q)SAR model EPI Suite v1.68. This is a valid model for this substance which falls into its applicability domain.

The partition coefficient of strontium oxalate was estimated to be -0.17.

Key value for chemical safety assessment

Log Kow (Log Pow):

-0.17

at the temperature of:

25 °C

Additional information

An analogue approach between strontium oxalate and oxalic acid can also be conducted. The hypothesis is that properties are likely to be similar or follow a similar pattern as a result of the presence of a common organic part. This is a reasonable assumption for the majority of organic salt compounds (e.g. metal salts of some organic acids). Indeed, the partition coefficient of the organic oxalic acid are of this order of magnitude. The LogKow of the organic part of strontium oxalate is estimated to be -1.74 (Episuite WSKOW v1.42) < < 4.5. As a BCF is more representative of the bioaccumulation of inorganic and dissociating substance, no additional testing is required for this endpoint.