Ethyl L-threoninate

Adsorption / desorption

Link to relevant study record(s)

Reference

Endpoint:

adsorption / desorption: screening

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2008

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: GLP study performed according to guideline

Reason / purpose for cross-reference:

reference to same study

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))

Deviations:

no

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))

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Type of method:

HPLC estimation method

Media:

soil

Test temperature:

30˚C

Details on study design: HPLC method:

EQUIPMENT
Column: 250X 4.6 mm Zorbax CN

MOBILE PHASES
- Experiments with additives carried out on separate columns:
- pH: 6.5 and 9.04, respectively
- Solutes for dissolving test and reference substances: Methanol/buffer, 55/45 v/v

DETERMINATION OF DEAD TIME
- Method: by inert substance (formamide) which are not retained by the column

REFERENCE SUBSTANCES
- Identity:Formamide, Acetanilide, N,N-dimethylbenzamide, Methylbenzoate, monuron and naphtalene

DETERMINATION OF RETENTION TIMES
- Quantity of test substance introduced in the column: 11.3 and 11.39 um at pH6 and pH9, respectively
- Quantity of reference substances: 4.25, 0.1, 0.21, 0.13, 0.23 and 0.2 um, for Formamide, Acetanilide, N,N-dimethylbenzamide, Methylbenzoate, monuron and naphtalene, respectively.

REPETITIONS
- Number of determinations: Two series of injections with duplicates injections of the test substance, and five calibration substances

Analytical monitoring:

yes

Type:

log Koc

Value:

>= 0.67 - <= 0.97 dimensionless

pH:

6

Type:

log Koc

Value:

0.54 dimensionless

pH:

9

Details on results (HPLC method):

- Graph of regression line attached

Conclusions:

At pH 6, the test substance eluted as two components, representing the ionised (6.4% of total area) and non-ionised (93.6%) species. The retention times corresponded to log Koc values of +0.675 and +0.975 respectively. These were within 95% confidence ranges of -0.055 to +1.035 and +0.41 to +1.27 respectively.
At pH 9, the test substance eluted as two components, again representing the ionised (1.8% of total area) and non-ionised (98.2%) species. The retention time of the ionised moiety was less than that of the formamide non-retained solute marker, and therefore does not permit generation of meaningful data. The retention time of the non-ionised moiety corresponded to a log Koc value of +0.54, within a 95% confidence range of -0.575 to +0.99.

On the basis of the relative low Log Koc values obtained it can be concluded that L-TEE is not likely to accumulate in soil.

Executive summary:

The distribution coefficient in soil (Log Koc) of L-TEE was estimated using the HPLC simulation technique under two conditions. As the test substance can undergo ionisation, the aqueous compartment of the mobile phase was controlled in separate tests at two buffered pH values, pH 6.15 (0.05 M citrate) and pH 9.04 (0.05 M borate). The mobile phase comprised methanol and buffer in the ratio 55 to 45v/v. All tests were performed at a controlled temperature of 30°C.

At pH 6, the test substance eluted as two components, representing the ionised (6.4% of total area) and non-ionised (93.6%) species. The retention times corresponded to log Koc values of +0.675 and +0.975 respectively. These were within 95% confidence ranges of -0.055 to +1.035 and +0.41 to +1.27 respectively.

At pH 9, the test substance eluted as two components, again representing the ionised (1.8% of total area) and non-ionised (98.2%) species. The retention time of the ionised moiety was less than that of the formamide non-retained solute marker, and therefore does not permit generation of meaningful data. The retention time of the non-ionised moiety corresponded to a log Koc value of +0.54, within a 95% confidence range of -0.575 to +0.99.

Description of key information

At pH 6, the test substance eluted as two components, representing the ionised (6.4% of total area) and non-ionised (93.6%) species. The retention times corresponded to log Koc values of +0.675 and +0.975, respectively. These were within 95% confidence ranges of -0.055 to +1.035 and +0.41 to +1.27 respectively.

At pH 9, the test substance eluted as two components, again representing the ionised (1.8% of total area) and non-ionised (98.2%) species. The retention time of the ionised moiety was less than that of the formamide non-retained solute marker, and therefore does not permit generation of meaningful data. The retention time of the non-ionised moiety corresponded to a log Koc value of +0.54, within a 95% confidence range of -0.575 to +0.99.

Key value for chemical safety assessment

Koc at 20 °C:

4.73