2-({2-[4-(dimethylamino)benzoyloxy]ethyl}(methyl)amino)ethyl 4-(dimethylamino)benzoate

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:

21 September 2006 to 17 October 2006

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline 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))

Version / remarks:

No. L225, 08.21.2001 Directive 2001/59/EC 28th amendment of the directive 67/548/EEC

GLP compliance:

yes (incl. QA statement)

Type of method:

HPLC estimation method

Specific details on test material used for the study:

Test article identification : LFC 2098
Chemical formula : C23H31O4N3
Molecular weight : 413
Chemical Class : Aminoester
Declared purity : 100.0 %
Preparation date : May 29, 2006

Radiolabelling:

no

Test temperature:

Ambient

Details on study design: HPLC method:

HPLC column : ChemService code No. 112
Teknokroma or equivalent : Hypersil CPS 5 µm, 250 x 4.6 mm id.
Detector : UV/Vis operating at 220 nm or 235 nm
Column temperature : room temperature
Eluent : Methanol / H3PO4 0.1% = 55/45 v/v
Eluent flow : 0.8 mL/min
Volume of injection : 10 µL
Total Analysis Time : 25 minutes

Analytical monitoring:

no

Details on matrix:

The HPLC is performed on analytical columns packed with a commercially available cyanopropyl solid phase containing lipophilic and polar moieties.
A moderately polar stationary phase based on a silica matrix is used.

Details on test conditions:

The HPLC is performed on analytical columns packed with a commercially available cyanopropyl solid phase containing lipophilic and polar moieties.
A moderately polar stationary phase based on a silica matrix is used.
While passing through the column along with the mobile phase the test substance interacts with the stationary phase; as a result of partitioning between mobile and stationary phases the test substance is retarded.
The dual composition of the stationary phase having polar and non-polar sites allows for interaction of polar and non-polar groups of a molecule in a similar way as is the case for organic matter in soil or sewage sludge matrices.
This enables the relationship between the retention time on the column and the adsorption coefficient on organic matter to be established. pH has a significant influence on sorption behaviour in particular for polar substances. For agricultural soils or tanks of sewage treatment plants pH normally varies between pH 5.5 and 7.5. For ionisable substances, two tests should be performed with both ionised and non-ionised forms in appropriate buffer solutions but only in cases where at least 10 % of the test compound will be dissociated within pH 5.5 to 7.5.
Since only the relationship between the retention on the HPLC column and the adsorption coefficient is employed for the evaluation, no quantitative analytical method is required and only the determination of the retention time is necessary. If a suitable set of reference substances is available and standard experimental conditions can be used, the method provides a fast and efficient way to estimate the adsorption coefficient Koc.

The experimental was performed initially with a mobile phase composed by methanol and water (55/45 % v/v), as recommended in the C.19 test method, but the test article was not eluted within 30 minutes.
The water fraction was substituted with a 0.1% phosphoric acid aqueous solution and this mobile phase was able to elute the test article more effectively.


Weigh 25 mg of each reference substance into 25 mL volumetric flasks using the analytical balance and dissolve to volume with methanol (~ 1 mg/mL).
Prepare, by dilution with methanol, the working standard solutions at 10 µg/mL or 20 µg/mL. Inject 10 µL into the HPLC and determine the retention times.

Weigh 25 mg of the test article into a 25 mL volumetric flask using the analytical balance and dissolve to volume with methanol (~ 1 mg/mL).
Prepare, by dilution 5:100 with methanol, the working test article solution at 50 µg/mL. Inject 10 µL into the HPLC and determine the retention times.

Sample No.:

#1

Duration:

30 min

Remarks:

Eluent: methanol and water (55/45 % v/v)

Sample No.:

#2

Duration:

25 min

Remarks:

Eluent : Methanol / H3PO4 0.1% = 55/45 v/v

Sample No.:

#1

Type:

log Koc

Value:

> 5 dimensionless

Remarks on result:

other: pH 5.5 - 7.5

Details on results (HPLC method):

Because the retention time of the test article was more higher than those of all standard substances, the log Koc value was calculated by extrapolation from the linear regression analysis performed using the least squares method.
The extrapolated log Koc value obtained was 13.23 (Koc > 1E+13), but we can reasonably assumed a more realistic log Koc > 5 (Koc > 10E+5), therefore LFC 2098 may be considered as strongly adsorbed by the soils.

Validity criteria fulfilled:

yes

Conclusions:

Because the retention time of the test article was more higher than those of all standard substances, the log Koc value was calculated by extrapolation from the linear regression analysis performed using the least squares method.
The extrapolated log Koc value obtained was 13.23 (Koc > 1E+13), but we can reasonably assumed a more realistic log Koc > 5 (Koc > 10E+5), therefore LFC 2098 may be considered as strongly adsorbed by the soils.

Executive summary:

Because the retention time of the test article was more higher than those of all standard substances, the log Koc value was calculated by extrapolation from the linear regression analysis performed using the least squares method.

The extrapolated log Koc value obtained was 13.23 (Koc > 1E+13), but we can reasonably assumed a more realistic log Koc > 5 (Koc > 10E+5), therefore LFC 2098 may be considered as strongly adsorbed by the soils.

Description of key information

Study conducted to recognised testing guidelines with GLP certification.

Key value for chemical safety assessment

Koc at 20 °C:

5