Amides, tall-oil fatty, N-[3-(dimethylamino)propyl]

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:

June 25 - July 19, 2010

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Justification for type of information:

It is assessed from the methods of manufacture the starting materials and the similarity of the end product compositions that EC272-047-7 is sufficiently similar in all respects to EC800-353-8 that it is a sensible approach to use a read-across approach. A comparison of the two substances and a read-across justification can be found in section 13 of this dataset.

Qualifier:

according to guideline

Guideline:

OECD Guideline 106 (Adsorption - Desorption Using a Batch Equilibrium Method)

Deviations:

yes

Remarks:

Three soils were used intead of five. Justification is given elsewhere in the RSS

Qualifier:

according to guideline

Guideline:

EU Method C.18 (Adsorption / Desorption Using a Batch Equilibrium Method)

Principles of method if other than guideline:

The number of soils used in this test deviated from the recommendation in OECD guideline 106 in that three soils were used instead of the recommended five soils. These deviations were based on results of earlier adsorption/ desorption tests with cationic surfactants. The partitioning to soil was not based on a Freundlich isotherm but was evaluated based on only one test concentration. The amines in the test substance will to a large extent be protonated under ambient conditions and will therefore interact with the negative surface of mineral particles or with negative charges of humic substances. The ionic interactions play a more important role than organic carbon content partitioning with organic matter. The log Koc was therefore considered as a poor predictor of the partitioning behaviour of the test substance in the environment, the determination of the Kd was also determined. The earlier results showed that using three soils, including at least one loamy sand and a clay soil, can give as much information as using the full number of soils. According to the Danish EPA (Influence of Sorption on the Degradation of Pesticides and other Chemicals in Soil, Danish EPA, 2004) a more reliable method of extrapolation to lower concentrations, was to use the data originating from the lowest measured concentration and to assume that the coefficient remained constant at lower concentrations. The test as described in this study plan was therefore performed using only one concentration which was as low as reasonably possible in relation to the detection limit.

GLP compliance:

yes (incl. QA statement)

Type of method:

batch equilibrium method

Media:

soil

Radiolabelling:

no

Test temperature:

Preliminary study: 19.8 to 20.3°C.
Definitive study: 19.1 to 24.1°C.

Analytical monitoring:

yes

Details on sampling:

The adsorption study was performed for 24 hours in duplicate for each soil type. After shaking, the centrifuge tubes were removed from the shaker and centrifuged for 5 minutes at 3000 g. Samples of the supernatant were prepared and analyzed. The pH was measured in the supernatant before and after contact of the test substance with soil using pH indicator strips. After the adsorption time of 24 hours the supernatant was sampled, removed and replaced by 40 mL of 0.01 M CaCl2 solution. The desorption part of the study was performed for 48 hours. The pH was measured in the supernatant of the 48 hr desorption sample directly after sampling.

Details on matrix:

This test was performed with three soils, LUFA soil 2.2, LUFA soil 6S and Eurosoil no. 4 and each soil was tested in duplicate. The applied initial test substance concentration for LUFA soil 2.2 was 1000 µg/L, for LUFA soil 6S and Eurosoil no. 4 this concentration was 5000 µg/L. This was accomplished by adding 100 µL of a stock solution with a concentration of respective 400 mg/L (LUFA 2.2) and 2000 mg/L (LUFA 6S and Eurosoil no. 4) to 39.9 mL of 0.01 M CaCl2 solution.
The selected soils were air-dried at ambient temperature (between 20 and 25°C) and sieved to a particle size < or = to 2 mm. The moisture content of each soil was determined on three aliquots by heating at 105°C until constant weight.

LUFA standard soil 2.2
Name: LUFA standard soil 2.2
Location: Großer Striet no. 585 Hanhofen Germany
Sampling date: 29-07-2009
Texture: Loamy sand
pH (0.01M CaCl2) 5.5 ± 0.1
Organic carbon (%): 2.09 ± 0.40
Particle size distribution: %clay (< 2µm): 6.4 ± 0.9% silt (2 – 50 µm): 11.6 ± 0.7% sand (50 – 2000 µm): 82.0 ± 0.7
CEC (meq/100g): 10.0 ± 0.5
Water holding capacity (%): 46.5 ± 6.0

LUFA standard soil 6S
Name: LUFA standard soil 6S
Location: In der unteren Hohnert no. 2412 Siebeldingen Germany
Sampling date: 17-08-2009
Texture: Clay
pH (0.01M CaCl2): 7.2 ± 0.1
Organic carbon (%): 1.69 ± 0.17
Particle size distribution: %clay (< 2µm): 41.7 ± 1.3% silt (2 – 50 µm): 36.1 ± 2.2% sand (50 – 2000 µm): 22.2 ± 1.5
CEC (meq/100g): 22.0 ± 6.6
Water holding capacity (%): 39.6 ± 5.0

Eurosoil no. 4
Name: Eurosoil no.4, certified reference material IRMM 443-4
Location: Data can be obtained from IRMM
Sampling date: Data can be obtained from IRMM
Texture (USDA): Silt
pH (0.01M CaCl2): 6.8 ± 0.6
Organic carbon (%): 1.31
Particle size distribution: %clay (< 2µm): 20.3% silt (2 – 50 µm): 75.7% sand (50 – 2000 µm): 4.1
CEC (meq/100g): 17.3

Type:

Kd

Value:

2 500

Remarks on result:

other: Lufa 2.2 soil

Type:

Kd

Value:

4 500

Remarks on result:

other: Lufa 6S soil

Type:

Kd

Value:

3 000

Remarks on result:

other: Eurosoil 4

Adsorption and desorption constants:

The equilibrium concentrations were measured to be between 32 – 184 µg/L for the different soil types by using an initial test substance concentration of 1000 µg/L for LUFA 2.2 and 5000 µg/L for LUFA 6S and Eurosoil 4. The observed adsorption parameters Kd and Koc values showed that the test substance adsorbed well to the tested soils. Moreover the values for Kdes were observed to be high. This means that the test substance was to a high percentage irreversible adsorbed to soil. pH values observed during the adsorption (24 hours) and desorption phase (48 hours) of the study were measured using a pH indicator stick and were found to be 7 for all samples.

Recovery of test material:

The recovery given by the mass balance, determined during the definitive test, did not meet the range of 70 to 110%. The applied extraction solution appeared not to be suitable for reliable extraction results. The final results of the Kd and Koc values have not been influenced by this.

Validity criteria fulfilled:

no

Remarks:

but without influence on results (see conclusions)

Conclusions:

The adsorption coefficient as expressed as the Kd of the test item was found to be in the range of 2500-4500 L/kg. This indicates that Amides, rape-oil, N-[3-(dimethylamino)propyl] will strongly adsorb to soils and sediments.
Quality criteria:
The recovery given by the mass balance, determined during the definitive test, did not meet the range of 70 to 110%. As the test substance was known to adhere easily to glass also an extraction of the glass vessel was determined. The amount of test substance extracted from the glass wall of the test vessel was very low. As the total recovery for the spiked aqueous sample was calculated from glass were reliable. Therefore, the test substance appeared to adsorb to a high percentage to soil and the used extraction solution was not suitable for reliable extraction results. The final results of the Kd and Koc values have not been influenced by this.
The temperature in the preliminary study varied from 19.8 to 20.3°C. In the definitive study the temperature varied from 19.1 to 24.1°C. During the preliminary test as well in the definitive test the temperatures varied outside the requirements of 20 - 25°C.

Executive summary:

The adsorption/desorption behaviour of Amides, rape-oil, N-[3-(dimethylamino)propyl] on soils was evaluated in a study performed in accordance with OECD testing guideline 106 and GLP requirements. At the test conditions the adsorption coefficient Kd was found to be in the range of 2500 to 4500 L/kg in the different soils tested. Consequently, the test substance is considered to be strongly sorptive to soil/sediment particles.

Description of key information

Due to the cationic surface-active properties will Amides, C18-unsatd., N-[3-(dimethylamino)propyl] adsorb strongly onto the solid phase of soil and sediments. The substance can adsorb both onto the organic fraction and, dependent on the chemical composition, onto the surface of the mineral phase, where sodium and potassium ions can be exchanged against the alkyl ammonium ion. The determination of a Koc from log Kow is not opportune, because the common equations for Koc derivation are not valid for both ionic and surface active substances. Therefore not the Koc values should be evaluated but the Kd values. Therefore the Kd values are reported and not the Koc values. 
Kd values range from 2500 to 4500 L/kg with an average of 3300 L/kg.

Key value for chemical safety assessment

Other adsorption coefficients

Type:

log Kp (solids-water in soil)

Value in L/kg:

3.5

Additional information

The adsorption/desorption behaviour of Amides, C18-unsatd., N-[3-(dimethylamino)propyl] on soils was evaluated in a study performed in accordance with OECD testing guideline 106 and GLP requirements. At the test conditions the adsorption coefficient Kd was found to be in the range of 2500 to 4500 L/kg in the different soils tested. Consequently, with an average of 3300 L/kg, the test substance is considered to be strongly sorptive to soil/sediment particles.