Propanoic acid, 2-hydroxy-, ammonium salt (1:1), (2S)-

Partition coefficient

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

partition coefficient

Type of information:

(Q)SAR

Adequacy of study:

key study

Study period:

2017-11-24

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:

Please refer to QPRF/QMRF documentation for detailed information on model suitability.

Qualifier:

according to guideline

Guideline:

other: Guidance on information requirements and chemical safety assessment Chapter R.6: QSARs and grouping of chemicals

Version / remarks:

May 2008

Principles of method if other than guideline:

QSAR prediction using KOWWIN v1.68 of EpiSuite v4.1. QSAR calculation is based on the fragment constant methodology.

GLP compliance:

no

Type of method:

other: QSAR calculation.

Partition coefficient type:

octanol-water

Specific details on test material used for the study:

SMILES: N(H)(H)(H)(H)OC(=O)C(O)C

Key result

Type:

log Pow

Partition coefficient:

-3.84

Temp.:

20 °C

Remarks on result:

other: pH not available in QSAR prediction.

Details on results:

see QPRF/QMRF

Conclusions:

The estimated log Pow = -3.84 for Ammonium-(S)-lactate is very low and suggests hydrophilic properties associated with only a minor potential for adsorption and bioaccumulation.

Executive summary:

In general, KOWWIN makes log P estimates that are “corrected for ionization”: i.e., KOWWIN estimates apply to compounds that are predominantly in a non-ionized form. However, KOWWIN is also capable to give log P estimates for “ion pair” compounds. Effectively, the estimate for Ammonium-(S)-lactate is an estimate for ionized lactic acid with additional fragment contributing factors for the ammonium counter ion. This approach is considered reasonable. The model result for Ammonium-(S)-lactate with a log Pow value of -3.84 matches the general behaviour for ionic compounds in a polar (water) and non-polar (octanol) environment and suggests hydrophilic properties associated with a minor potential for adsorption and bioaccumulation. Ammonium-(S)-lactate is inside the applicability domain of the model and the result is considered adequate for a regulatory purpose.

Reference 2

Endpoint:

partition coefficient

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

supporting study

Justification for type of information:

For details and justification of read-across please refer to the report attached in section 13 of IUCLID.

Reason / purpose for cross-reference:

read-across source

Type:

log Pow

Partition coefficient:

ca. -0.54

Temp.:

25 °C

Conclusions:

Experimental determination of the partition coefficient of lactic acid is technically not feasible due to poor analytical detectability.

Executive summary:

Due to the poor UV-absorption ability of the test item an enzymatic reaction in combination with UV-detection was performed. However, no suitable method for the detection of lactic acid in n-octanol and/or water in the required concentration range could be developed (technically not feasible). Therefore, the partition coefficient of the test substance was calculated using the Rekker calculation method by the software PrologP 6.0, module in Pallas 3.0, CompuDrug International, San Francisco, CA, USA.

The calculated log Pow is –0.54.

This information is used in a read-across approach in the assessment of the target substance.

For justification of read-across please refer to the attached read-across report (see IUCLID section 13).

Description of key information

The estimated log Pow for Ammonium-(S)-lactate is -3.84. Experimental determination is technically not feasible since the UV absorption properties prevent both the HPLC and the flask method.

Key value for chemical safety assessment

Log Kow (Log Pow):

-3.84

at the temperature of:

20 °C

Additional information

In general, KOWWIN makes log P estimates that are “corrected for ionization”: i.e., KOWWIN estimates apply to compounds that are predominantly in a non-ionized form. However, KOWWIN is also capable to give log P estimates for “ion pair” compounds. Effectively, the estimate for Ammonium-(S)-lactate is an estimate for ionized lactic acid with additional fragment contributing factors for the ammonium counter ion. This approach is considered reasonable. The model result for Ammonium-(S)-lactate with a log Pow value of -3.84 matches the general behaviour for ionic compounds in a polar (water) and non-polar (octanol) environment and suggests hydrophilic properties associated with a minor potential for adsorption and bioaccumulation. Ammonium-(S)-lactate is inside the applicability domain of the model and the result is considered adequate for a regulatory purpose.

KOWWIN considers two structural fragments, -O-N (oxygen, nitrogen attach) and {-O- or -S-} to nitrogen (+5 valence) which are not present in Ammonium-(S)-lactate, having an ionic structure. Despite the wrongly positive contribution of these two fragments to the overall estimate, the estimated log P for Ammonium-(S)-lactate is still very low. Therefore, this model error is considered negligible.

-O-N (oxygen, nitrogen attach) fragment contributing factor: 0.2352;

{-O- or -S-} to nitrogen (+5 valence) fragment contributing factor: 1.7500 (estimated coefficient).

To further support the applicability of the QSAR estimation for the log Pow of Ammonium-(S)-lactate, an experimental study for L(+)-lactic acid is provided.