Lactic acid

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

Qualifier:

according to guideline

Guideline:

OECD Guideline 121 (Estimation of the Adsorption Coefficient (Koc) on Soil and on Sewage Sludge using High Performance Liquid Chromatography (HPLC))

Qualifier:

according to guideline

Guideline:

EU Method C.19 (Estimation of the Adsorption Coefficient (KOC) on Soil and Sewage Sludge Using High Performance Liquid Chromatography (HPLC))

GLP compliance:

yes

Type of method:

HPLC estimation method

Media:

other: HPLC column

Radiolabelling:

no

Test temperature:

Column temperature 35 °C

Details on study design: HPLC method:

EQUIPMENT
- Apparatus: Alliance Separation Module 2695
- Detection system: Dual lambda absorbance detector 2487


MOBILE PHASES
- Type: 30/70 methanol/water (neutral); 30/70 methanol/phosphate buffer (pH 2.0)
- Solutes for dissolving test and reference substances: water (lactic acid); methanol (phenol)


DETERMINATION OF DEAD TIME
- Method: by means of homologous series / by inert substances which are not retained by the column


REFERENCE SUBSTANCES
- Identity: Phenol


DETERMINATION OF RETENTION TIMES
- Quantity of test substance introduced in the column: 10 µl; 209 ng (neutral), 135 ng (pH 2)
- Quantity of reference substances: 10 µl; 100 ng


REPETITIONS
- Number of determinations: all samples were measured in duplicate; controls were injected once


EVALUATION
- Calculation of capacity factors k': Not calculated
- Calculation of retention times: Not given other than in (single) chromatogram run printouts
- Determination of the log Koc value: <1.32 (i.e. < phenol log Koc)

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:

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

Principles of method if other than guideline:

QSAR calculation

GLP compliance:

no

Type of method:

other: QSAR

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.

Description of key information

Both estimated soil organic carbon-water partitioning coefficients for the read across substance L(+) Lactic acid 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 1L/kg. These QSAR calculations are supported by an experimental study, indicating that the KOC of lactic acid is much lower than 20.9.

Key value for chemical safety assessment

Koc at 20 °C:

1