C16-18 (evennumbered, C18 unsaturated) alkyl bis(2-hydroxyethyl) amine oxide

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:

2017-08-14 to 2017-09-28

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

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

Version / remarks:

The number of soils which were used deviates from the guideline recommendation in the guideline as three soils were used instead of the recommended five soils. The Freundlich isotherms were not determined and the adsorption / desorption behavior was investigated based on one test item concentration. This was the lowest reasonable test concentration which could be used in relation to the detection limit. These deviations from the guideline were on request of the sponsor and are based on earlier adsorption / desorption studies with cationic surfactants

Samples were centrifuged < 3000 g if glass vessels had to be used. Higher centrifugation forces would have destroyed these vials.

Deviations:

yes

Remarks:

see above at "Version / remarks"

Qualifier:

according to guideline

Guideline:

other: Council Regulation (EC) No. 440/2008, Method C.18 (2008)

GLP compliance:

yes (incl. QA statement)

Type of method:

batch equilibrium method

Media:

soil

Radiolabelling:

no

Test temperature:

Nominal: 20 ± 2 °C

Analytical monitoring:

yes

Details on sampling:

Test Procedure

Test vessels
120 mL disposable glass bottles with aluminium tops with butyl/PTFE seals.
50 mL disposable centrifugation tubes during Tier 1 for soil / solution ratio of 1:40.

Concentration for adsorption / desorption experiments
1.5 mg/L test item; The concentration was found to be suitable for measurements above the limit of quantification of the analytical method (20 µg/L test item) which was assigned with regard to the three analytes.

Stock solutions
A stock solution of 1.5 g/L of the test substance in 50 mL acetonitrile was prepared. 0.1 volume-% (0.1 mL) of this stock solution, related to the volume of the aqueous phase in the soil suspensions, were used for spiking.

Preparation of the soil samples (conditioning)
The soils were weighed into the test vessels and anappropriate volume of 0.01 M CaCl2-solution was added. After agitation overnight (12 h minimum), the samples were used for adsorption experiments.

Preparation of the samples for adsorption experiments
The soil samples were conditioned as described above.0.1 volume-% of the stock solutions, related to the volume of the aqueous phase in the soil suspensions was added in order to adjust the test concentrations. Afterwards, the samples were agitated.

Preparation of the samples for desorption experiments
Samples at adsorption equilibrium were used for this purpose. After completion of the adsorption experiments the test vessels were centrifuged, weighed and the supernatant was replaced by fresh 0.01 M CaCl2-solution. Then the test vessels were agitated again to investigate the desorption behavior of the test item.
 
Samples for analysis
The soil suspensions were centrifuged after agitation at ≥ 3000 rpm (1881 g) to separate the phases, followed by analysing the concentration of the analytes in aqueous phase by LC-MS/MS. For analysis of the soil, the aqueous phase was decanted and the soil was extracted, if feasible. During Tier 2, test vessels were extracted / rinsed with acetonitrile to determine test vessel adsorption. Extracts were also analysed by LC-MS/MS.

Replicates
All samples were prepared in duplicate.

CONTROLS
CaCl2-solution was conditioned as described above, followed by separation of the aqueous phase by centrifugation and filtration. Then the aqueous phase was fortified acc. to the concentrations used for the test item samples to verify the stability of the test item in the aqueous phase under test conditions. The samples were agitated as long as the test item sample with the longest agitation period.

Replicates
Duplicates


BLANK
Blank samples were prepared for all soils as described for the test item samples but without fortification with the test item. The samples were agitated as long as the samples with the longest agitation period.

Replicates
Duplicates (Tier 1), single (Tier 2 and Tier 3)

Sample Preparation

Dilution medium
Acetonitrile : HPLC-water (50:50)

Standards
A stock solution of 1.5 g/L of Tallow Bis(2-hydroxyethyl) amineoxide in 50 mL acetonitrile was prepared. The solution was diluted to 7 calibration standards in the range of 5 to 100 µg/L with dilution medium.

Aqueous phase
All samples were centrifuged ≥ 3000 rpm (1881 g). An aliquot of each aqueous sample was stabilized by dilution with acetonitrile (factor 2). Samples were diluted to calibration range with dilution medium, if necessary.

Test vessel adsorption
After sampling of the aqueous phase during Tier 1 and Tier 2, the test vessels were emptied and rinsed with demineralized water. Acetonitrile was used for extraction of the test item from the test vessel. Therefore ultrasound was used for 10 min and the vessel was shaken 30 min on a shaker. HPLC-water was used to dilute by factor 2. Acetonitrile : HPLC-water (50:50) was used for further dilutions to calibration range, if necessary.


Soil extraction (Tier 1)
After removal of the aqueous phase, 30 mL acetonitrile containing 1 % trifluoro acetic acid was used to rinse the soil from the test vessel into centrifugation tubes. Ultrasound was used for 15 min and the vessel was shaken 30 min on a shaker. The suspensions were centrifuged at 10000 g for 5 min. The extraction was repeated twice with 20 mL acetonitrile containing 1 % trifluoro acetic acid without using ultrasound. The extracts were transferred quantitatively into a 100 mL measuring flask and filled up with acetonitrile containing 1 % trifluoro acetic acid. HPLC-water was used to dilute by factor 2. Acetonitrile : HPLC-water (50:50) was used for further dilutions to calibration range. Prior to using acetonitrile containing 1 % trifluoro acetic acid the extraction was once conducted containing 2 % formic acid.

 
Soil extraction (“fresh spikes”)
To prove feasibility of extraction, conditioned soil was spiked with the test item and extracted directly after spiking:
The soil was weighed into 50 mL centrifugation tube and was spiked with the test item. Then the samples were extracted with acetonitrile containing 1 % trifluoro acetic acid. For parameters of the extraction method see above. Extracts were transferred quantitatively into a 100 mL measuring flask and filled up with acetonitrile containing 1 % trifluoro acetic acid. HPLC-water was used to dilute by factor 2. Acetonitrile : HPLC-water (50:50) was used for further dilutions to calibration range.

Samples for method validation
Samples were prepared as described above. The aqueous phases were decanted and spiked with test item at 1 x LOQ level. Additional aqueous phase conditioned with LUFA soil 2.4 was spiked with test item at 10 x LOQ level. All samples were diluted with acetonitrile by factor 2. The samples of 10 x LOQ level were additionally diluted with acetonitrile : HPLC-water (50:50) by factor 10 to calibration range for analysis of Tallow bis(2-hydroxyethyl)amineoxide.

Matrix no.:

#1

Matrix type:

loamy sand

% Clay:

8.5

% Silt:

11.3

% Sand:

80.2

% Org. carbon:

1.47

pH:

7.1

CEC:

7.6 other: mval/100 g

Matrix no.:

#2

Matrix type:

other: silty sand

% Clay:

8.6

% Silt:

29.3

% Sand:

62.1

% Org. carbon:

0.412

pH:

7

CEC:

4.9 other: mval/100 g

Matrix no.:

#3

Matrix type:

clay loam

% Clay:

25.2

% Silt:

42.3

% Sand:

32.6

% Org. carbon:

1.74

pH:

7.2

CEC:

22 other: mval/100 g

Details on matrix:

Relevant Characteristics of Test Matrices

Reason for the selection
The content of organic carbon of the selected soils differ significantly. These matrices are suitable for the conduction of the study because all parameters with impact on the adsorption / desorption behavior of a chemical substance were considered.

Origin of soils
Landwirtschaftliche Untersuchungs- und Forschungsanstalt LUFA Speyer, Obere Langgasse 40, 67346 Speyer, Germany

Storage at test facility
Room temperature, in closed containers

Expiry date
LUFA 2.2 (batch: F2.2 4016): 2021-10-24
LUFA 2.3 (batch: F2.3 4116): 2021-10-24
LUFA 2.4 (batch: F2.4 4116): 2021-10-24

Details on test conditions:

CaCl2 solution:
Deionised water was used to prepare the CaCl2 solution (0.01 M).

Soil / Solution ratio
Tier 1: 1:40 and 1:100
Tier 2 and Tier 3: 1:100

Agitation
By overhead shaker for soil / solution ratio of 1:40.
By horizontal shaker for soil / solution ratio of 1:100.
Frequency was adjusted to avoid sedimentation of soil particles during treatment.

Test temperature:
20 +/- 2 °C 

Key result

Sample No.:

#10

Type:

Kd

Value:

2 517 L/kg

pH:

7

Temp.:

20 °C

Matrix:

LUFA 2.2: Loamy sand

% Org. carbon:

1.47

Remarks on result:

other: Mean of three main constituents

Key result

Sample No.:

#11

Type:

Kd

Value:

1 157 L/kg

pH:

7.3

Temp.:

20 °C

Matrix:

LUFA2.3: Silty sand

% Org. carbon:

0.412

Remarks on result:

other: Mean of three main constituents

Key result

Sample No.:

#12

Type:

Kd

Value:

3 139 L/kg

pH:

8

Temp.:

20 °C

Matrix:

LUFA 2.4: Clayey loam

% Org. carbon:

1.74

Remarks on result:

other: Mean of three main constituents

Sample No.:

#1

Type:

Kd

Value:

2 160 L/kg

pH:

7

Temp.:

20 °C

Matrix:

LUFA 2.2 soil/solution ratio 1:100

% Org. carbon:

1.47

Remarks on result:

other: Tallow Bis(2-hydroxyethyl) amineoxide C16 saturated compound

Sample No.:

#1

Type:

Koc

Value:

146 959 L/kg

pH:

7

Temp.:

20 °C

Matrix:

LUFA 2.2 soil/solution ratio 1:100

% Org. carbon:

1.47

Remarks on result:

other: Tallow Bis(2-hydroxyethyl) amineoxide C16 saturated compound

Sample No.:

#1

Type:

other: Kdes

Value:

2 123 L/kg

pH:

7

Temp.:

20 °C

Matrix:

LUFA 2.2 soil/solution ratio 1:100

% Org. carbon:

1.47

Remarks on result:

other: Tallow Bis(2-hydroxyethyl) amineoxide C16 saturated compound

Sample No.:

#2

Type:

Kd

Value:

349 L/kg

pH:

7.3

Temp.:

20 °C

Matrix:

LUFA 2.3 soil/solution ratio 1:100

% Org. carbon:

0.412

Remarks on result:

other: Tallow Bis(2-hydroxyethyl) amineoxide C16 saturated compound

Sample No.:

#2

Type:

Koc

Value:

84 739 L/kg

pH:

7.3

Temp.:

20 °C

Matrix:

LUFA 2.3 soil/solution ratio 1:100

% Org. carbon:

0.412

Remarks on result:

other: Tallow Bis(2-hydroxyethyl) amineoxide C16 saturated compound

Sample No.:

#2

Type:

other: Kdes

Value:

552 L/kg

pH:

7.3

Temp.:

20 °C

Matrix:

LUFA 2.3 soil/solution ratio 1:100

% Org. carbon:

0.412

Remarks on result:

other: Tallow Bis(2-hydroxyethyl) amineoxide C16 saturated compound

Sample No.:

#3

Type:

Kd

Value:

1 151 L/kg

pH:

8

Temp.:

20 °C

Matrix:

LUFA 2.4 soil/solution ratio 1:100

% Org. carbon:

1.74

Remarks on result:

other: Tallow Bis(2-hydroxyethyl) amineoxide C16 saturated compound

Sample No.:

#3

Type:

Koc

Value:

66 134 L/kg

pH:

8

Temp.:

20 °C

Matrix:

LUFA 2.4 soil/solution ratio 1:100

% Org. carbon:

1.74

Remarks on result:

other: Tallow Bis(2-hydroxyethyl) amineoxide C16 saturated compound

Sample No.:

#3

Type:

other: Kdes

Value:

1 135 L/kg

pH:

8

Temp.:

20 °C

Matrix:

LUFA 2.4 soil/solution ratio 1:100

% Org. carbon:

1.74

Remarks on result:

other: Tallow Bis(2-hydroxyethyl) amineoxide C16 saturated compound

Sample No.:

#4

Type:

Kd

Value:

2 598 L/kg

pH:

7

Temp.:

20 °C

Matrix:

LUFA 2.2 soil/solution ratio 1:100

% Org. carbon:

1.47

Remarks on result:

other: Tallow Bis(2-hydroxyethyl) amineoxide C18 unsaturated compound

Sample No.:

#4

Type:

Koc

Value:

176 714 L/kg

pH:

7

Temp.:

20 °C

Matrix:

LUFA 2.2 soil/solution ratio 1:100

% Org. carbon:

1.47

Remarks on result:

other: Tallow Bis(2-hydroxyethyl) amineoxide C18 unsaturated compound

Sample No.:

#4

Type:

other: Kdes

Value:

2 240 L/kg

pH:

7

Temp.:

20 °C

Matrix:

LUFA 2.2 soil/solution ratio 1:100

% Org. carbon:

1.47

Remarks on result:

other: Tallow Bis(2-hydroxyethyl) amineoxide C18 unsaturated compound

Sample No.:

#5

Type:

Kd

Value:

455 L/kg

pH:

7.3

Temp.:

20 °C

Matrix:

LUFA 2.3 soil/solution ratio 1:100

% Org. carbon:

0.412

Remarks on result:

other: Tallow Bis(2-hydroxyethyl) amineoxide C18 unsaturated compound

Sample No.:

#5

Type:

Koc

Value:

110 408 L/kg

pH:

7.3

Temp.:

20 °C

Matrix:

LUFA 2.3 soil/solution ratio 1:100

% Org. carbon:

0.412

Remarks on result:

other: Tallow Bis(2-hydroxyethyl) amineoxide C18 unsaturated compound

Sample No.:

#5

Type:

other: Kdes

Value:

697 L/kg

pH:

7.3

Temp.:

20 °C

Matrix:

LUFA 2.3 soil/solution ratio 1:100

% Org. carbon:

0.412

Remarks on result:

other: Tallow Bis(2-hydroxyethyl) amineoxide C18 unsaturated compound

Sample No.:

#6

Type:

Kd

Value:

1 454 L/kg

pH:

8

Temp.:

20 °C

Matrix:

LUFA 2.4 soil/solution ratio 1:100

% Org. carbon:

1.74

Remarks on result:

other: Tallow Bis(2-hydroxyethyl) amineoxide C18 unsaturated compound

Sample No.:

#6

Type:

Koc

Value:

83 582 L/kg

pH:

8

Temp.:

20 °C

Matrix:

LUFA 2.4 soil/solution ratio 1:100

% Org. carbon:

1.74

Remarks on result:

other: Tallow Bis(2-hydroxyethyl) amineoxide C18 unsaturated compound

Sample No.:

#6

Type:

other: Kdes

Value:

1 516 L/kg

pH:

8

Temp.:

20 °C

Matrix:

LUFA 2.4 soil/solution ratio 1:100

% Org. carbon:

1.74

Remarks on result:

other: Tallow Bis(2-hydroxyethyl) amineoxide C18 unsaturated compound

Sample No.:

#7

Type:

Kd

Value:

2 772 L/kg

pH:

7

Temp.:

20 °C

Matrix:

LUFA 2.2 soil/solution ratio 1:100

% Org. carbon:

1.47

Remarks on result:

other: Tallow Bis(2-hydroxyethyl) amineoxide C18 saturated compound

Key result

Sample No.:

#7

Type:

Koc

Value:

188 584 L/kg

pH:

7

Temp.:

20 °C

Matrix:

LUFA 2.2 soil/solution ratio 1:100

% Org. carbon:

1.47

Remarks on result:

other: Tallow Bis(2-hydroxyethyl) amineoxide C18 saturated compound

Sample No.:

#7

Type:

other: Kdes

Value:

1 722 L/kg

pH:

7

Temp.:

20 °C

Matrix:

LUFA 2.2 soil/solution ratio 1:100

% Org. carbon:

1.47

Remarks on result:

other: Tallow Bis(2-hydroxyethyl) amineoxide C18 saturated compound

Sample No.:

#8

Type:

Kd

Value:

2 721 L/kg

pH:

7.3

Temp.:

20 °C

Matrix:

LUFA 2.3 soil/solution ratio 1:100

% Org. carbon:

0.412

Remarks on result:

other: Tallow Bis(2-hydroxyethyl) amineoxide C18 saturated compound

Sample No.:

#8

Type:

Koc

Value:

660 354 L/kg

pH:

7.3

Temp.:

20 °C

Matrix:

LUFA 2.3 soil/solution ratio 1:100

% Org. carbon:

0.412

Remarks on result:

other: Tallow Bis(2-hydroxyethyl) amineoxide C18 saturated compound

Sample No.:

#8

Type:

other: Kdes

Value:

3 783 L/kg

pH:

7.3

Temp.:

20 °C

Matrix:

LUFA 2.3 soil/solution ratio 1:100

% Org. carbon:

0.412

Remarks on result:

other: Tallow Bis(2-hydroxyethyl) amineoxide C18 saturated compound

Sample No.:

#9

Type:

Kd

Value:

6 939 L/kg

pH:

8

Temp.:

20 °C

Matrix:

LUFA 2.4 soil/solution ratio 1:100

% Org. carbon:

1.74

Remarks on result:

other: Tallow Bis(2-hydroxyethyl) amineoxide C18 saturated compound

Sample No.:

#9

Type:

Koc

Value:

398 782 L/kg

pH:

8

Temp.:

20 °C

Matrix:

LUFA 2.4 soil/solution ratio 1:100

% Org. carbon:

1.74

Remarks on result:

other: Tallow Bis(2-hydroxyethyl) amineoxide C18 saturated compound

Sample No.:

#9

Type:

other: Kdes

Value:

6 759 L/kg

pH:

8

Temp.:

20 °C

Matrix:

LUFA 2.4 soil/solution ratio 1:100

% Org. carbon:

1.74

Remarks on result:

other: Tallow Bis(2-hydroxyethyl) amineoxide C18 saturated compound

Concentration of test substance at end of adsorption equilibration period:

At an initial test substance concentration of 1.5 mg/L using a soil solution ratio of 1:100 after an equilibrium time of 24 hours
The following concentrations were observed at the end of the equilibration time:
LUFA 2.2: C16: 1.08 µg/L; C18=: 1.04 µg/L; C18: 0.88 µg/L
LUFA 2.3: C16: 5.20 µg/L; C18=: 4.85 µg/L; C18: 0.862 µg/L
LUFE 2.4: C16: 1.99 µg/L; C18=: 1.84 µg/L; C18: 0.367 µg/L

Transformation products:

no

Temperature

The temperature was in the range of 20 ± 2 °C during the course of the study

Soil Dry Weights

The soil dry weight of each soil type used was determined.

 

 Soil Dry Weights

Mean values (n = 3)

	Soil
	LUFA 2.2	LUFA 2.3	LUFA 2.4
soil dry weight [%]	92.3	96.1	90.4

pH Values

The pH values of the aqueous media of the test systems were measured before and after equilibration with the corresponding soils and after addition of the test item. Results are shown in the following table.

 

 pH Values of the Aqueous Media

Soil / Solution Ratio 1:100

	Soil
	LUFA 2.2	LUFA 2.3		LUFA 2.4
0.01 M CaCl2	7.1	7.0	7.2
after soil contact	6.9	7.1		7.4
after addition of the test item	7.0	7.3		8.0

 

 

Tier 1 - Adsorption

LUFA 2.2 and LUFA 2.4 were used for preliminary investigations on the adsorption behavior of the test item with soil / solution ratios of 1:40 and 1:100 at a concentration of 1.5 mg/L. An adsorption of ≥ 89% was determined for the three analytes in both soils. The equilibrium of the adsorption was reached after 24 h. Test item control samples (samples without soil) showed that test vessel adsorption is possible. For this reason, test vessel adsorption was taken into account for calculations during adsorption experiments. Concentrations and sampling points for Tier 2 have been assigned based on results in the following tables. A soil / solution ratio of 1:100 was used for the further experiments in Tier 2 and Tier 3 to reduce the test item depletion in the aqueous phase as much as possible.

 

Tier 1: LUFA 2.2 – Soil / Solution Ratios 1:40 and 1:100

Soil / Solution Ratio	Applied concentration, test item [mg/L]	Sampling point [h]	Adsorption C16:0 Compound [%]	Adsorption C18:1 Compound [%]	Adsorption C18:0 Compound [%]
1:40	1.5	24	98	99	96
1:100	1.5	24	95	96	96

 

Tier 1: LUFA 2.4 – Soil / Solution Ratios 1:40 and 1:100

Soil / Solution Ratio	Applied concentration, test item [mg/L]	Sampling point [h]	Adsorption C16:0 Compound [%]	Adsorption C18:1 Compound [%]	Adsorption C18:0 Compound [%]
1:40	1.5	24	99	100	96
1:100	1.5	24	89	92	98

 

Tier 1 - Test Vessel Adsorption

The test item adsorption to the test vessels in test item controls was determined in Tier 1 for the samples with the longest agitation period in polypropylene centrifugation tubes and in glass vials. Adsorption in these samples was lower for all analytes when glass was used. For this reason, glass vials were used for the experiments in Tier 2 and Tier 3. No adsorption on test vessels was observed in the soils suspensions (soil / solution ratio 1:100).

Nevertheless, test vessel adsorption was taken into account for the respective calculations in Tier 2.

 

Tier 1: LUFA 2.2 – Test Vessel Adsorption

Soil / Solution Ratio	Applied concentration, test item [mg/L]	Sampling point [h]	Adsorption C16:0 Compound [%]	Adsorption C18:1 Compound [%]	Adsorption C18:0 Compound [%]
1:100 gl	1.5	24	0	0	0

 

Tier 1:LUFA 2.4 – Test Vessel Adsorption

Soil / Solution Ratio	Applied concentration, test item [mg/L]	Sampling point [h]	Adsorption C16:0 Compound [%]	Adsorption C18:1 Compound [%]	Adsorption C18:0 Compound [%]
1:100 gl	1.5	24	0	0	0

 

Tier 1: LUFA 2.2 – Test Vessel Adsorption – Test Item Control Samples

0.01 M CaCl₂was conditioned with LUFA 2.2

Soil / Solution Ratio	Applied concentration, test item [mg/L]	Sampling point [h]	Adsorption C16:0 Compound [%]	Adsorption C18:1 Compound [%]	Adsorption C18:0 Compound [%]
1:40 pp	1.5	24	22	25	41
1:40 gl	1.5	24	10	13	28
1:100 gl	1.5	24	8	9	16

 

Tier 1: LUFA 2.4 – Test Vessel Adsorption – Test Item Control Samples

0.01 M CaCl₂was conditioned with LUFA 2.4

Soil / Solution Ratio	Applied concentration, test item [mg/L]	Sampling point [h]	Adsorption C16:0 Compound [%]	Adsorption C18:1 Compound [%]	Adsorption C18:0 Compound [%]
1:40 pp	1.5	24	18	25	43
1:40 gl	1.5	24	10	10	37
1:100 gl	1.5	24	2	2	13

pp                    = 50 mL polypropylene centrifugation tube as test vessel

gl                     = 50 mL disposable glass bottle as test vessel

 

Tier 1 - Extraction from Soil / Mass Balance

Different solvents have been tested for soil extraction during method development (non-GLP). During Tier 1, samples were extracted after 24 h. The best results were achieved with acetonitrile containing 1 % trifluoro acetic acid. In addition, freshly spiked samples were extracted by the same method, to prove feasibility of extraction. Recovery rates of 105% to 110% of the nominal concentration for the analytes from LUFA 2.2 and 100% to 108% from LUFA 2.4 were obtained.

 

Tier 1:Mass Balance LUFA 2.2 Soil / Solution Ratio 1:100
applied test item concentration: 1500 µg/L, n=2

	Sampling point [h]	Recovery rate from aqueous phase [%]	Recovery rate from test vessel^2) [%]	Recovery rate from solid phase [%]	Mass balance^1) [%]
C16:0 Compound	24 III	6	< LCL	93	95
	24 IV	5	< LCL	85
C18:1 Compound	24 III	5	< LCL	91	91
	24 IV	4	< LCL	82
C18:0 Compound	24 III	5	0	105	107
	24 IV	3	< LCL	101

 

Tier 1: Mass Balance LUFA 2.4 Soil / Solution Ratio 1:100
applied test item concentration: 1500 µg/L, n=2

	Sampling point [h]	Recovery rate from aqueous phase [%]	Recovery rate from test vessel^2) [%]	Recovery rate from solid phase [%]	Mass balance^1) [%]
C16:0 Compound	24 III	11	< LCL	79	92
	24 IV	11	< LCL	84
C18:1 Compound	24 III	8	< LCL	81	90
	24 IV	8	< LCL	82
C18:0 Compound	24 III	2	< LCL	98	103
	24 IV	2	< LCL	104

III, IV                = replicate number

1)                      =Sum of aqueous phase, solid phase and test vessel, mean value

2)                      = obtained from replicates I and II

< LCL               = measured value below lowest calibration level

 

Tier 2 - Adsorption Kinetics

The determination for adsorption kinetics was performed with a nominal test item concentration of 1.5 mg/L. A soil / solution ratio of 1:100 was used and concentrations of the test item were measured in aqueous phase and in extracts of the test vessels at defined sampling points. The equilibrium was reached within 24 hours. The following tables show the percentage of adsorption at equilibrium, the time needed to reach the adsorption equilibrium as well as the obtained distribution coefficients K_d and their corresponding organic carbon normalized distribution coefficients K_OC. The test item shows high adsorption within a few hours to all tested soils.

 

Equilibrium Time, Measured Amounts in Aqueous Phase and Soil Extracts, Percent of Adsorption and Distribution Coefficients K_d, K_OC for C16:0 Compound

Applied concentration, test item:          1.5 mg/L

Applied amount, test item:                     150 µg

Applied amount, a.i.:22.6 µg

n = 2; soil / solution ratio: 1:100

V_aq= 100 mL

Soil Type	teq [h]	msoil  [g]	m^adsaq(eq) [µg]	m^adss(eq) [µg]	Kd [mL/g]	%OC	KOC[mL/g]	Adsorption [%]
LUFA 2.2	24	0.923	1.08	21.6	2160	1.47	146959	95
LUFA 2.3	24	0.961	5.20	17.4	349	0.412	84739	77
LUFA 2.4	24	0.904	1.99	20.7	1151	1.74	66134	91

V_aq            =used volume of aqueous phase

t_eq              =time to reach equilibrium

m_soil          =used amount of soil (dry weight)

m^ads_aq        =amount of a.i. in the aqueous phase at equilibrium

m^ads_s          =amount of a.i. in the soil at equilibrium

%OC         =percentage of organic carbon content in the soil

 

Equilibrium Time, Measured Amounts in Aqueous Phase and Soil Extracts, Percent of Adsorption and Distribution Coefficients K_d, K_OC for C18:1 Compound

Applied concentration, test item:          1.5 mg/L

Applied amount, test item:                     150 µg

Applied amount, a.i.:26.1 µg

n = 2; soil / solution ratio: 1:100

V_aq= 100 mL

Soil Type	teq [h]	msoil [g]	m^adsaq(eq) [µg]	m^adss(eq) [µg]	Kd[mL/g]	%OC	KOC [mL/g]	Adsorption [%]
LUFA 2.2	24	0.923	1.04	25.0	2598	1.47	176714	96
LUFA 2.3	24	0.961	4.85	21.2	455	0.412	110408	81
LUFA 2.4	24	0.904	1.84	24.2	1454	1.74	83582	93

 

 

Equilibrium Time, Measured Amounts in Aqueous Phase and Soil Extracts, Percent of Adsorption and Distribution Coefficients K_d, K_OC for C18:0 Compound

Applied concentration, test item:          1.5 mg/L

Applied amount, test item:                     150 µg

Applied amount, a.i.:23.4 µg

n = 2; soil / solution ratio: 1:100

V_aq= 100 mL

Soil Type	teq[h]	msoil[g]	m^adsaq(eq) [µg]	m^adss(eq) [µg]	Kd[mL/g]	%OC	KOC[mL/g]	Adsorption [%]
LUFA 2.2	24	0.923	0.880	22.5	2772	1.47	188584	96
LUFA 2.3	24	0.961	0.862	22.5	2721	0.412	660354	96
LUFA 2.4	24	0.904	0.367	23.0	6939	1.74	398782	98

V_aq            =used volume of aqueous phase

t_eq              =time to reach equilibrium

m_soil          =used amount of soil (dry weight)

m^ads_aq        =amount of a.i. in the aqueous phase at equilibrium

m^ads_s          =amount of a.i. in the soil at equilibrium

%OC         =percentage of organic carbon content in the soil

Tier 3 - Desorption Kinetics

The desorption behavior of the test item was determined after 24 h adsorption. The following tables show the desorption coefficient K_des. The results show that the test item adsorption is not completely reversible since the desorption is only between 2 % und 16 %. Details are showen in the tables below.

 

Percent of Desorption and Desorption Coefficient K_des for C16:0 Compound

Applied concentration, test item:          1.5 mg/L

Applied amount, test item:                     150 µg

Applied amount, a.i.:22.6 µg

n = 2; soil / solution ratio: 1:100

V_aq= 100 mL

Soil Type	teq[h]	msoil[g]	m^desaq(eq) [µg]	m^adss(eq) [µg]	Kdes[mL/g]	Desorption [%]
LUFA 2.2	6	0.923	1.05	21.6	2123	5
LUFA 2.3	2	0.961	2.84	17.9	552	16
LUFA 2.4	2	0.904	1.80	20.3	1135	9

 

Percent of Desorption and Desorption Coefficient K_des for
C18:1 Compound

Applied concentration, test item:          1.5 mg/L

Applied amount, test item:                     150 µg

Applied amount, a.i.:26.1 µg

n = 2; soil / solution ratio: 1:100

V_aq= 100 mL

Soil Type	teq[h]	msoil[g]	m^desaq(eq) [µg]	m^adss(eq) [µg]	Kdes[mL/g]	Desorption [%]
LUFA 2.2	6	0.923	1.16	25.1	2240	5
LUFA 2.3	2	0.961	2.79	21.5	697	13
LUFA 2.4	2	0.904	1.63	24.0	1516	7

 

 

Percent of Desorption and Desorption Coefficient K_des for
C18:0 Compound

Applied concentration, test item:          1.5 mg/L

Applied amount, test item:                     150 µg

Applied amount, a.i.:23.4 µg

n = 2; soil / solution ratio: 1:100

V_aq= 100 mL

Soil Type	teq[h]	msoil[g]	m^desaq(eq) [µg]	m^adss(eq) [µg]	Kdes[mL/g]	Desorption [%]
LUFA 2.2	6	0.923	1.33	22.5	1722	6
LUFA 2.3	24	0.961	0.609	22.7	3783	3
LUFA 2.4	4	0.904	0.369	22.9	6759	2

V_aq            =used volume of aqueous phase

t_eq              =time to reach equilibrium

m_soil          =used amount of soil (dry weight)

m^des_aq        =amount a.i. measured in the aqueous phase after desorption step

(entrained water taken into account)

m^ads_s          =amount of a.i. adsorbed to soil at equilibrium

Validity criteria fulfilled:

yes

Conclusions:

Valid guideline study with slightly adapted conditions. Adaptations are justified based on specific type of sorption behaviour of the cationic surfactant. Droge et al 2013 (RSS included) showed that sorption of cationic surfactants is mainly driven by ionic interaction. This explains the non-linear sorption observed. In case non-linear sorption is observed extrapolation to lower environmentally realistic concentrations from a Freundlich isotherm is useless and can lead to erroneous predictions. As an alternative the approach as suggested by the Danish EPA (RSS included) is used where the Kd is determined at a concentration as low as reasonably possible and it is assumed that at this low concentration the Kd can linearly be extrapolated to lower concentrations.

Executive summary:

The adsorption / desorption behavior of Tallow Bis(2 -hydroxyethyl) amineoxide was investigated in three different soils according to OECD guideline 106. Distribution coefficients K_d and organic carbon normalized distribution coefficients K_OC were determined with a single concentration. In addition, the desorption behavior / reversibility of the adsorption from the soils was investigated. The distribution coefficients K_des were calculated for this purpose.

 

RelevantCharacteristics of Test Matrices

	Soils
	LUFA 2.2	LUFA 2.3	LUFA 2.4
Soil Type^1)	Loamy sand	Silty sand	Clayey loam
pH (0.01 M CaCl2)^2)	7.1	7.0	7.2
Organic Carbon [%]^3)	1.47	0.412	1.74
Clay (<0.002 mm) [%]^3)	8.5	8.6	25.2
Silt (0.002-0.063 mm) [%]^3)	11.3	29.3	42.3
Sand (0.063-2 mm) [%]^3)	80.2	62.1	32.6
Cation Exchange Capacity [mval/100g]^3)	7.6	4.9	22

1)according to German DIN

2) data determined during the course of the study

3)determined at Agrolab Agrar und Umwelt GmbH (non-GLP)

 

Based on results of preliminary investigations during Tier 1, a soil / solution ratio of 1:100 was used for adsorption experiments. Experiments for adsorption and desorption kinetics were conducted with a nominal test item concentration of 1.50 mg/L. Three active ingredients C16-Tallow Bis(2-hydroxyethyl) amineoxide(16:0), C18unsaturated-Tallow Bis(2-hydroxyethyl) amineoxide(18:1) and C18saturated-Tallow Bis(2-hydroxyethyl) amineoxide(18:0) were used as lead components of the test item and were analysed by LC-MS/MS.Data are given for each analyte in this report.

The table below shows obtained distribution coefficients K_d and their corresponding organic carbon normalized distribution coefficients K_OC. Furthermore, the mobility of the test item in the investigated matrices was classified according to Mc Call et al(1980). Additionally, the desorption coefficient K_des ispresented in the summarizing table. A mean weighted average value was calculated for all endpoints. A typical distribution of the lead components of 29.8% (C16:0), 34.3% (C18:1) and 30.8% (C18:0) was considered for this purpose.

 

Summarized Endpoints forTallow Bis(2-hydroxyethyl) amineoxideand the Active Ingredients

Mobility according to Mc Call et al. (1980): K_OC 0 – 50 very high, K_OC 50 – 150 high, K_OC 150 – 500 medium, K_OC 500 – 2000 low, K_OC 2000 – 5000 slight, K_OC > 5000 immobile

	caq(eq) [µg/L]	Kd [mL/g]	KOC [mL/g]	Kdes [mL/g]	Mobility according to McCall et al.
Soil/Solution Ratio	1:100
C16:0 Compound
LUFA 2.2	1.08	2160	146959	2123	immobile
LUFA 2.3	5.20	349	84739	552	immobile
LUFA 2.4	1.99	1151	66134	1135	immobile
C18:1 Compound
LUFA 2.2	1.04	2598	176714	2240	immobile
LUFA 2.3	4.85	455	110408	697	immobile
LUFA 2.4	1.84	1454	83582	1516	immobile
C18:0 Compound
LUFA 2.2	0.880	2772	188584	1722	immobile
LUFA 2.3	0.862	2721	660354	3783	immobile
LUFA 2.4	0.367	6939	398782	6759	immobile
Tallow Bis(2-hydroxyethyl) amineoxide– Weighted Average Value
LUFA 2.2	-	2517	171223	2035	immobile
LUFA 2.3	-	1157	280834	1653	immobile
LUFA 2.4	-	3139	180402	3098	immobile

c_aq(eq)            = concentration in the aqueous phase at adsorption equilibrium; value was calculated for
  Tallow Bis(2-hydroxyethyl) amineoxide from measured
  concentrations of the active ingredients and taking the respective contents into account

 

The results show that Tallow Bis(2 -hydroxyethyl) amineoxide adsorbs strongly to all tested soils with Koc values > 5000 and is therefore considered to be immobile in soils according to Mc Call et al. The desorption was not completely reversible. The Freundlich isotherm was not determined and the adsorption / desorption behavior was investigated based on one test item concentration. These deviations from the guideline were on request of the sponsor and are based on earlier adsorption / desorption studies with cationic surfactants and the conclusions from the Danish EPA (see RSS).

Description of key information

A refined sorption/desorption test according to OECD 106 with tallow bis(2hydroxyethyl)amineoxide resulted in equilibrium constants (Kd's) of 2517, 1157 and 3139 L/kg for loamy sand, silty sand and clayey loam soil. As there is no direct relationship with the sorption behaviour of the substance and the organic carbon content of the soil because other soil properties like the Cation Exchange Capacity and the pH are maybe even more important to predict the sorption behaviour, no Koc's are given.

The mean Kd of 2271 L/kg is used for risk assessment.

 

Key value for chemical safety assessment

Other adsorption coefficients

Type:

log Kp (solids-water in soil)

Value in L/kg:

3.356

at the temperature of:

20 °C

Other adsorption coefficients

Type:

log Kp (solids-water in sediment)

Value in L/kg:

3.356

at the temperature of:

20 °C

Other adsorption coefficients

Type:

log Kp (solids-water in suspended matter)

Value in L/kg:

3.657

at the temperature of:

20 °C

Additional information

Due to the cationic surface-active properties will tallow bis(2 -hydroxyethyl) amineoxide adsorb relatively strongly onto the solid phase of soil and sediments. These substances 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.

The sorption test is performed according to OECD 106 with some adaptations. These adaptations are considered justified based on specific type of sorption behaviour of the cationic surfactant. Droge et al 2013 showed that sorption of cationic surfactants is mainly driven by ionic interaction. This type of sorption explains the frequently observed non-linear sorption. In case non-linear sorption is observed extrapolation to lower environmentally realistic concentrations using the Freundlich isotherm is useless and can lead to erroneous predictions. As an alternative the approach as suggested by the Danish EPA is considered to be a better alternative where the Kd is determined at a concentration which is as low as reasonably possible and in addition it is assumed that at this low concentration the Kd can linearly be extrapolated to lower concentrations.  

Relevant Characteristics of the soils used in the sorption/desorption test

	Soils
	LUFA 2.2	LUFA 2.3	LUFA 2.4
Soil Type^1)	Loamy sand	Silty sand	Clayey loam
pH (0.01 M CaCl2)^2)	7.1	7.0	7.2
Organic Carbon [%]^3)	1.47	0.412	1.74
Clay (<0.002 mm) [%]^3)	8.5	8.6	25.2
Silt (0.002-0.063 mm) [%]^3)	11.3	29.3	42.3
Sand (0.063-2 mm) [%]^3)	80.2	62.1	32.6
Cation Exchange Capacity [mval/100g]^3)	7.6	4.9	22

1)according to German DIN

2) data determined during the course of the study

3)determined at Agrolab Agrar und Umwelt GmbH (non-GLP)

 

Based on results of preliminary investigations during Tier 1, a soil / solution ratio of 1:100 was used for adsorption experiments. Experiments for adsorption and desorption kinetics were conducted with a nominal test concentration of 1.50 mg/L. Three active ingredients C16 -Bis(2 -hydroxyethyl) amineoxide(16:0), C18 unsaturated Bis(2 -hydroxyethyl) amineoxide(18:1) and C18 saturated Bis(2-hydroxyethyl) amineoxide(18:0) were used as lead components of the test item and were analysed by LC-MS/MS.

The table below shows obtained distribution coefficients K_d and their corresponding organic carbon normalized distribution coefficients K_OC. As indicated these Koc's will not be used for risk assessment! Furthermore, the mobility of the test item in the investigated matrices was classified according to Mc Call et al(1980). Additionally, the desorption coefficient K_des is presented in the summarizing table. A mean weighted average value was calculated for all endpoints. A typical distribution of the lead components of 29.8% (C16:0), 34.3% (C18:1) and 30.8% (C18:0) was considered for this purpose.

Summarized Endpoints forTallow Bis(2-hydroxyethyl) amineoxide and the Active Ingredients

Mobility according to Mc Call et al. (1980): K_OC 0 – 50 very high, K_OC 50 – 150 high, K_OC 150 – 500 medium, K_OC 500 – 2000 low, K_OC 2000 – 5000 slight, K_OC > 5000 immobile

	caq(eq) [µg/L]	Kd [mL/g]	KOC [mL/g]	Kdes [mL/g]	Mobility according to McCall et al.
Soil/Solution Ratio	1:100
C16:0 Compound
LUFA 2.2	1.08	2160	146959	2123	immobile
LUFA 2.3	5.20	349	84739	552	immobile
LUFA 2.4	1.99	1151	66134	1135	immobile
C18:1 Compound
LUFA 2.2	1.04	2598	176714	2240	immobile
LUFA 2.3	4.85	455	110408	697	immobile
LUFA 2.4	1.84	1454	83582	1516	immobile
C18:0 Compound
LUFA 2.2	0.880	2772	188584	1722	immobile
LUFA 2.3	0.862	2721	660354	3783	immobile
LUFA 2.4	0.367	6939	398782	6759	immobile
Tallow Bis(2-hydroxyethyl) amineoxide– Weighted Average Value
LUFA 2.2	-	2517	171223	2035	immobile
LUFA 2.3	-	1157	280834	1653	immobile
LUFA 2.4	-	3139	180402	3098	immobile

c_aq(eq) = concentration in the aqueous phase at adsorption equilibrium; value was calculated for Tallow Bis(2-hydroxyethyl) amineoxide from measured   concentrations of the active ingredients and taking the respective contents into account

 

The results show that Tallow Bis(2 -hydroxyethyl) amineoxide adsorbs relatively strongly to all tested soils with Koc values > 5000 L/kg and is therefore considered to be immobile in soils according to Mc Call et al. The desorption was not completely reversible. .

For the prediction of the partitioning of Tallow bis(2 -hydroxyethyl)amineoxide in soil, sediment and suspended matter the mean K_d as observed for the three soils of 2271 L/kg will be used.

Because there is relation of the sorption of Tallow bis(2 -hydroxyethyl)amineoxide to the organic carbon fraction allone there will be also no principal difference between the sorption to soil and sediments considering the sorption properties. The Kd value for soil will also be used for sediment and suspended particles.

In the table below the distribution constants used in this assessment is summarized:

Distribution constants to be used for Tallow bis(2 -hydroxyethyl)amineoxide

Kpsoil		2271 L/kg		Ksoil-water		3406.5 m^3/m^3
Kpsusp		4542 L/kg		Ksusp-water		1135.5 m^3/m^3
Kpsed		2271 L/kg		Ksed-water		1135.5 m^3/m^3

 

With a Kp_suspof 4542 L/kg and a concentration of 15 mg/L suspended matter in surface waters, the adsorbed fraction is calculated as 6.4%.