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

Adsorption / desorption

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

adsorption / desorption, other

Type of information:

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

Adequacy of study:

key study

Justification for type of information:

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

Reason / purpose for cross-reference:

read-across source

Radiolabelling:

no

Key result

Type:

Koc

Value:

ca. 1 L/kg

Remarks on result:

other: The Koc may vary by pH. The estimated value is applicable to the neutral pH range.

Validity criteria fulfilled:

not applicable

Conclusions:

The adsorption/desorption coefficient of lactic acid was estimated to be approximately 1 L/kg using the QSAR model KOCWIN v2.00.

Executive summary:

The adsorption/desorption coefficient of lactic acid was estimated to be approximately 1 L/kg using the QSAR model KOCWIN v2.00.

This information is used in a read-across approach in the assessment of the target substance. For details and justification of read-across please refer to the read-across report attached to IUCLID section 13.

Reference 2

Endpoint:

adsorption / desorption, other

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 read-across report attached to IUCLID section 13 of.

GLP compliance:

no

Type of method:

other: literature review

Media:

soil

Specific details on test material used for the study:

- NH3 (un-ionized ammonia) and NH4+ (ionized ammonia or ammonium)

Validity criteria fulfilled:

not applicable

Conclusions:

The environmental fate of ammonia (NH3) and Ammonium (NH4+) is discussed in the present report, hence fulfilling the scope of the OECD guideline 106, i.e. “predict partitioning under a variety of environmental conditions”. Ammonium is most likely to be found in soil, where it is adsorbed to the negatively charged soil particles. The adsorption mechanisms can be exchangeable (chemical binding), non-exchangeable (by fixation), reaction with organic matter and physical attractive forces. The report states that ammonia "is unlikely to leach to groundwater except under unusual circumstances, such as when the cation exchange capacity of the soil is exceeded.”because ammonia is poorly mobile in soil.

Executive summary:

Ammonia/ammonium is strongly adsorbed on soil, sediment particles and colloids in water. This adsorption results in high concentrations of sorbed ammonia/ammonium in oxidised sediments. Under anoxic conditions, the adsorptive capacity of sediments is less, resulting in the release of ammonia to either the water column or an oxidized sediment layer above. In clay, ammonium tends to be absorbed on the negative adsorption sites of clay colloids. Ammonia/ammonium may substitute for potassium in the lattice structure of a clay mineral. Ammonia/ ammonium is bound in soil by the attraction of the positive charge on the ammonium ion to the negatively charged soil micelles. In soil, ammonium is adsorbed primarily by four mechanisms: chemical (exchangeable), fixation (non-exchangeable), reaction with organic matter and physical attractive forces.

Description of key information

No experimental data on ammonium-S-lactate are available. In aqueous environments ammonium-S-lactate fully dissociates into NH4+ ions and lactate ions. Therefore, the adsorption/desorption behaviour of ammonium-S-lactate in the environment can be understood in terms of the adsorption/desorption behaviour of NH3/NH4+ and lactic acid. To evaluate the adsorption/desorption of ammonium-S-lactate read-across from lactic acid is performed.

An experimental study is scientifically not necessary since the log P_ow for ammonium-S-lactate is expected to be low based on low log P_ow values of both ionic components (below 0, respectively).

The adsorption/desorption coefficient of lactic acid was estimated to be approximately 1 L/kg using the QSAR model KOCWIN v2.00. Therefore, lactic acid is equally distributed between water and organic matter. Ammonia/ammonium is poorly mobile in soil. However, ammonium is a central element of the global natural nitrogen cycle and therefore of no concern in the context of the uses of ammonium-(S)-lactate.

Key value for chemical safety assessment

Koc at 20 °C:

1

Additional information

This information is used in a read-across approach in the assessment of the target substance. For details and justification of read-across please refer to the read-across report attached to IUCLID section 13.