Sodium lactate

Adsorption / desorption

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

adsorption / desorption: screening

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.

Reason / purpose for cross-reference:

read-across source

Type:

Koc

Value:

< 20.9 dimensionless

Type:

log Koc

Value:

< 1.32 dimensionless

Details on results (HPLC method):

Lactic acid eluted before phenol; phenol has a designated log Koc of 1.32. No relevant differences in the results were observed at neutral pH and pH 2.0.

Validity criteria fulfilled:

yes

Conclusions:

Lactic acid log Koc < 1.32.

Executive summary:

The adsorption coefficient (Koc) of lactic acid 93 % aq. on soil and on sewage sludge was determined using high performance liquid chromatography (HPLC). The Koc and log Koc value of the test substance at neutral pH and at pH 2 was < 20.9 and < 1.32, respectively.

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.

Reason / purpose for cross-reference:

read-across source

Type:

Koc

Value:

1 L/kg

Remarks on result:

other: Estimate from Molecular Connectivity Index

Type:

Koc

Value:

0.222 L/kg

Remarks on result:

other: Estimate from Log Kow

Validity criteria fulfilled:

not applicable

Conclusions:

The estimated KOC based on the KOW data equals 0.2218 L/kg. The calculated KOC from the molecular connectivity index is 1L/kg.

Executive summary:

Both estimated soil organic carbon-water partitioning coefficients indicate that the substance does not inherent a high tendency to adsorb on to soil particles, but is more likely to be found in aquatic compartments. The estimated KOC based on the KOW data equals 0.2218 L/kg. The calculated KOC from the molecular connectivity index is 1 L/kg.

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 3

Endpoint:

adsorption / desorption: screening

Data waiving:

study scientifically not necessary / other information available

Justification for data waiving:

the study does not need to be conducted because the substance has a low octanol water partition coefficient and the adsorption potential of this substance is related to this parameter

the study does not need to be conducted because the physicochemical properties of the substance indicate that it can be expected to have a low potential for adsorption

Description of key information

Experimental determination of the adsorption/desorption coefficient of Sodium lactate is not required based on its physical-chemical properties. Adsorptivity is predicted to be insignificant, as derived from the partition coefficient (log P_ow).

Additional information

According to Annex VIII, section 9.3.1, column 2 of the REACH Regulation, the adsorption coefficient (Koc) does not need to be experimentally determined if the substance has a low octanol-water partition coefficient. The log Kow of Sodium lactate was determined to be < -1.52, indicating a very low potential to adsorb to organic carbon. The possibility that adsorption is driven by other factors than lipophilicity (e.g., surface activity, ionizability, cf. Regulation (EU) 2021/979) is assessed as follows: The surface tension of Sodium lactate in water is 71.8 mN/m, thus the substance is not surface active. Furthermore, Sodium lactate fully dissociates into Na+ ions and lactate in aqueous environments. The adsorption/desorption behaviour of Sodium lactate can thus be understood in terms of the adsorption/desorption behaviour of sodium salts and lactic acid. For lactic acid a QSAR prediction for the Koc is available, assuming the substance to be in fully protonated state, i.e., at maximized lipophilicity. The corresponding Koc is predicted to be 1 L/kg, demonstrating that at pH values maximizing lipophilicity (hence adsorption) the adsorption potential of lactate/lactic acid is negligible. Adsorption of sodium is not predicted to occur to any appreciable extent since sodium, as an inorganic ionic species, is not susceptible to pH-dependent changes in lipophilicity and/or adsorptivity. Therefore, the waiving criteria according to Annex VIII, column 2 of section 9.3.1 of the REACH Regulation, as amended by Regulation (EU) 2021/979, are fulfilled. Performance of an adsorption/desorption study is not required.