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Environmental fate & pathways

Adsorption / desorption

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Administrative data

Endpoint:
adsorption / desorption: screening
Type of information:
migrated information: read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
supporting study
Reliability:
3 (not reliable)
Rationale for reliability incl. deficiencies:
other: Guideline compliant GLP study. Since lactide undergoes immediate hydrolysis in contact with water, forming lactic acid, this is the moiety of interest by read-across. However, the study is not valid due to lack of a calibration curve.

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2008

Materials and methods

Test guidelineopen allclose all
Qualifier:
according to
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:
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

Test material

Reference
Name:
Unnamed
Type:
Constituent
Type:
Constituent
Details on test material:
Batch No. 0712002519
Radiolabelling:
no

Study design

Test temperature:
Column temperature: 35 °C

HPLC method

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)

Results and discussion

Adsorption coefficientopen allclose all
Type:
Koc
Value:
< 20.9
Type:
log Koc
Value:
< 1.32

Results: HPLC method

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.

Applicant's summary and conclusion

Validity criteria fulfilled:
no
Remarks:
With only one reference substance, no calibration curve could be established. Therefore, the study is not valid.
Conclusions:
Lactic acid log Koc < 1.32. This result can be adopted for DD-lactide, in view of its rapid hydrolysis, forming lactic acid.
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.