1,3-Propanediamine, N-[3-((C11-14, C13-rich)oxy)propyl]- branched acetate

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:

2009 - 2010

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

equivalent or similar to guideline

Guideline:

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

Deviations:

yes

Remarks:

3 soils tested instead of required 5 soils

GLP compliance:

yes (incl. QA statement)

Type of method:

batch equilibrium method

Media:

soil

Radiolabelling:

no

Test temperature:

20 - 25°C

Analytical monitoring:

yes

Details on sampling:

The adsorption study was run for 24 hours. After shaking the centrifuge tubes were removed from the shaker and centrifuged for 5 minutes at 3000g. An aliquot of the supernatant was taken from each sample and blank and transferred into a HPLC vial containing already leaching solution. All samples were analyzed according to the analytical method. After the adsorption time of 24 hours the supernatant was sampled, removed and replaced by 40 mL of 0.01M CaCl2 solution. The desorption part of the study was run for 48 hours. Sampling and pretreatment was performed as described above followed by analyzing.

Details on matrix:

Name: LUFA standard soil 2.2
Location: Groβer 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

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

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

Details on test conditions:

TEST CONDITIONS
- Buffer: 0.01M CaCl2
- pH: 7
- Suspended solids concentration: 1:100
- other:

TEST SYSTEM
- Type, size and further details on reaction vessel: 40 mL glass centrifuge tube
- Water filtered (i.e. yes/no; type of size of filter used, if any): no
- Amount of soil/sediment/sludge and water per treatment (if simulation test):
- Soil/sediment/sludge-water ratio (if simulation test):
- Number of reaction vessels/concentration: 2
- Measuring equipment: LC-MS
- Test performed in closed vessels due to significant volatility of test substance: yes
- Test performed in open system: no
- Method of preparation of test solution:
The applied initial test substance concentration for LUFA soil 2.2 was 0.263 mg/L, for LUFA soil 6S this concentration was 2.51 mg/L and for Eurosoil no. 4 this concentration was 1.035 mg/L. This was accomplished by adding 100 µL of a stock solution with a concentration of respective 105 mg/L (LUFA 2.2), 1004 mg/L (LUFA 6S) and 414 mg/L (Eurosoil no. 4) to 39.9 mL of 0.01M CaCl2 solution.
- Are the residues from the adsorption phase used for desorption: yes
- Other:
About 400 mg soil and 39.9 mL of 0.01M CaCl2 solution, resulting in a soil/test solution ratio of 1:100, was equilibrated in a capped glass centrifuge tube on a shaker during one night in the dark. The pH value was measured before spiking with the test substance. The actual test, performed in duplicate for each soil type, was started by adding 100 µL of the respective diluted stock solutions to the equilibrated soil slurries. The glass centrifuge tubes were placed on the shaker again. Blanks were prepared in the same way but omitting the spiking with the diluted stock solution. An adsorption control sample was prepared by filling a centrifuge tube with 39.9 mL of 0.01M CaCl2 solution and 100 µL of the diluted stock solution followed by treatment in the same way as described above.

Sample No.:

#1

Duration:

24 h

Initial conc. measured:

105 other: mg/L

pH:

7

Temp.:

22 °C

Sample No.:

#2

Duration:

24 h

Initial conc. measured:

1 004 other: mg/L

pH:

7

Temp.:

22 °C

Sample No.:

#3

Duration:

24 h

Initial conc. measured:

414 other: mg/L

pH:

7

Temp.:

22 °C

Sample no.:

#1

Duration:

48 h

Conc. of adsorbed test mat.:

8.4 other: µg/L

pH:

7

Temp.:

22 °C

Sample no.:

#2

Duration:

48 h

Conc. of adsorbed test mat.:

45 other: µg/L

pH:

7

Temp.:

22 °C

Sample no.:

#3

Duration:

48 h

Conc. of adsorbed test mat.:

19.2 other: µg/L

pH:

7

Temp.:

22 °C

Computational methods:

- Adsorption and desorption coefficients (Kd): see below
- Freundlich adsorption and desorption coefficients: -
- Slope of Freundlich adsorption/desorption isotherms: -
- Adsorption coefficient per organic carbon (Koc): see below
- Regression coefficient of Freundlich equation -
- Other:
Soil type Kd Koc Kdes
10^2 cm3/g 10^4 cm3/g 10^3 cm3/g
LUFA 2.2 9.4 4.5 3.1
LUFA 6S 25.0 14.8 6.0
Eurosoil 4 25.9 19.8 5.7

Type:

Kd

Value:

940

Temp.:

22 °C

% Org. carbon:

2.09

Remarks on result:

other: LUFA soil 2.2

Type:

Kd

Value:

2 500

Temp.:

22 °C

% Org. carbon:

1.69

Remarks on result:

other: LUFA soil 6S

Type:

Kd

Value:

2 590

Temp.:

22 °C

% Org. carbon:

1.31

Remarks on result:

other: Eurosoil no. 4

Adsorption and desorption constants:

Soil type Kd Koc Kdes
10^2 cm3/g 10^4 cm3/g 10^3 cm3/g
LUFA 2.2 9.4 4.5 3.1
LUFA 6S 25.0 14.8 6.0
Eurosoil 4 25.9 19.8 5.7

Recovery of test material:

Replicate Recovery (%)
C12 C13 Total
A 120 119 120
B 90 90 90
C 97 97 97

Concentration of test substance at end of adsorption equilibration period:

LUFA 2.2: 33.9 µg/L (mean value of 8 replicates); initial test concentration: 263 µg/L
LUFA 6S: 95.7 µg/L (mean value of 8 replicates): initial test concentration: 2510 µg/L
Eurosoil no. 4: 44.2 µg/L (mean value of 8 replicates); initial test concentration: 1035 µg/L

Concentration of test substance at end of desorption equilibration period:

LUFA 2.2: 8.4 µg/L (mean value of 8 replicates)
LUFA 6S: 45µg/L (mean value of 8 replicates)
Eurosoil no. 4: 19.2 µg/L (mean value of 8 replicates)

Transformation products:

not measured

Details on results (Batch equilibrium method):

PRELIMINARY TEST
- Sample purity: see CoA
- Weighed soil: 400 mg
- Volume of CaCl2 solution: 40 mL
- Initial test substance concentration: 200 mg/L + 40 mg/L
- Test substance concentration in final solution: 0.1 mg/L + 0.5 mg/L


MAIN TEST: PERFORMANCE
- Test material stability during adsorption/desorption phase: see recoevery results
- Experimental conditions maintained throughout the study: Yes
- Buffer/test substance interactions affecting sorption: no
- Further chemical interactions: no

Validity criteria fulfilled:

yes

Conclusions:

The observed adsorption parameters Kd and Koc values showed that the test substance adsorbed well to the 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 the soil.

Executive summary:

An adsorption and desorption test for the reaction mixtureN-(3-(Tridecyloxy)propyl)-1,3-propane diamine, acetate and N-(3-(Tridecyloxy)propyl)- 1,3-propane diamine has been performed according to adapted OECD guideline for testing of chemicals, No. 106.

A summary of the results is presented below:

 

Soil	Clay	Silt	Sand	CEC	pH	Org C	Caq	Kd	Koc
	(%)	(%)	(%)	(meq/100g)		(%)	(µg/l)	(10^2cm^3/g)	(10^4cm^3/g)
Speyer2.2	6.4	11.6	82.0	10	5.5	2.09	33.9	9.4	4.5
Eurosoil 4	20.3	75.7	4.1	17.3	6.8	1.31	44.2	25.9	19.8
Speyer6S	42.7	36.1	22.2	22	7.2	1.69	95.7	25	14.8

 

Description of key information

The adsorption coefficient (Kd) was determined in a test according to OECD TG 106.  The Kd values are in the range  of  940 – 2590 L/kg for three different soils.  The mean value of 2010 L/kg will be used for risk assessment purposes. The substances will adsorb strongly onto the solid phase of soil and sediments due to the cationic surface-active properties. 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 is not valid for both ionic and surface active substances.

Key value for chemical safety assessment

Other adsorption coefficients

Type:

other: Kp (solids-water in soil)

Value in L/kg:

2 010

at the temperature of:

22 °C

Other adsorption coefficients

Type:

other: Kp (solids-water in sediment)

Value in L/kg:

2 010

at the temperature of:

22 °C

Other adsorption coefficients

Type:

other: Kp (solids- water in suspended matter)

Value in L/kg:

4 020

at the temperature of:

22 °C

Additional information

Due to the cationic surface-active properties will etherdiamine (N-(3-(Tridecyloxy)propyl)- 1,3-propane diamine, acetate and -(Tridecyloxy)propyl)- 1,3-propane diamine) 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 is not valid for both ionic and surface active substances.

The adsorption behaviour of etherdiamine was studied in a batch equilibrium experiment according to a refined OECD 106 (Vos, 2010). Three soils were used Speyer 2.2, loamy sand: 6.4% clay, 2.1% organic carbon; Euro soil 4, silt: 20.3% clay, 1.3% organic carbon and Speyer S6, clay: 42.7% clay, 1.7% organic carbon) encompassing a range of % clay and organic matter. The test substance adsorbed partially onto the container walls which was considered for the determination of the adsorption coefficients. Adsorption kinetics was determined by measurements at different sampling times (up to 24 h), an equilibrium was reached after 3 hours. Desorption occurred to a lesser extent than adsorption. The table below presents a summary of the most important soil properties and observed partitioning constants.

 

Soil properties and related soil partitioning constants:

 

Soil	Clay	Silt	Sand	CEC	pH	Org C	Caq	Kd	Koc
	(%)	(%)	(%)	(meq/100g)		(%)	(µg/l)	(10^2cm^3/g)	(10^4cm^3/g)
Speyer2.2	6.4	11.6	82.0	10	5.5	2.09	33.9	9.4	4.5
Eurosoil 4	20.3	75.7	4.1	17.3	6.8	1.31	44.2	25.9	19.8
Speyer6S	42.7	36.1	22.2	22	7.2	1.69	95.7	25	14.8

 

From the data it can be observed that the sorption onto Speyer 6S is much higher than to Speyer 2.2 despite of the higher organic matter content in Speyer 2.2 soil. This can be explained that ionic interactions play a more important role than hydrophobic partitioning with organic matter. Alkyl ammonium ions can interact with the surface of mineral particles or with negative charges of humic substances.

The number of soils which was used in this test deviates from the recommendation in OECD guideline 106 (2000) in that three soils were used instead of the recommended five soils. In addition is the partitioning to soil is not based on a Freundlich isotherm but evaluated based on only one test concentration. These deviations are based on results of earlier adsorption desorption tests with cationic surfactants. 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 hydrophobic partitioning with organic matter. The log Koc is therefore considered as a poor predictor of the partitioning behaviour of cationic surfactants in the environment. These earlier results showed that using three soils with at least one loamy sand and a clay soil, can give as much information as using the full number of soils. These earlier tests also revealed that only rarely linear adsorption isotherms were obtained for cationic surfactants and that extrapolation to lower concentrations based on these non-linear isotherms leads to unrealistic results (e.g. RAR primary fatty amines Oct. 2008). According to the Danish EPA (2004) a more reliable method of extrapolation to lower concentrations, is to use the data originating from the lowest measured concentration and to assume that the coefficient remains constant at lower concentrations. The test as described is therefore performed using only one concentration which is as low as reasonably possible in relation to the detection limit.

The initial concentration used for the determination of the soil partitioning constant were 0.26, 2.5 and 1 mg/L for respectively Speyer 2.2, S6 and Eurosoil 4. The observed aquatic equilibrium concentrations in the experiment range from 34 to 96 µg/L.

For the prediction of the partitioning of the etherdiamine in soil, sediment and suspended matter not the K_d based on organic matter will used but the uncorrected K_d because the relation between the organic matter concentration and the sorption observed alone is not sufficient. Research sponsored by APAG CEFIC is currently performed at University of Leipzich (UFZ, K.U. Goss, S. Droge) and Utrecht (IRAS, J. Hermens) to improve the knowledge on bioavailability and partitioning to soil and sediment.

Because there is no principal difference between soil and sediments considering the sorption properties and because for cationic surfactants the degree of sorption is not related to the organic carbon content, the value for soil will also be used for sediment and suspended particles.

 

In table below the distribution constants (mean values of the 3 tested soils) used in this assessment is summarized:

Table. :Distribution constants for etherdiamine

Kpsoil		2010 L^.kg^-1		Ksoil-water		3015 m^3.m^-3
Kpsusp		4020 L^.kg^-1		Ksusp-water		1005 m^3.m^-3
Kpsed		2010 L^.kg^-1		Ksed-water		1005 m^3.m^-3

 

With a Kp_suspof 4020 L/kg and a concentration of 15 mg/L suspended matter in surface waters, the adsorbed fraction is calculated as ±7%.