Dodecyldimethylamine 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:

From Apr. 9, 2002 to Jun. 28, 2002

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)

Deviations:

yes

Remarks:

3 soil types tested instead of 5.

GLP compliance:

yes (incl. QA statement)

Remarks:

OECD principles of GLP

Type of method:

batch equilibrium method

Media:

soil

Radiolabelling:

no

Test temperature:

23.6 °C ( Range 23.4-23.7 °C)

Analytical monitoring:

yes

Details on sampling:

- Concentrations (Nominal): Adsorption test: 0, 4004 µg/L;
- Sampling interval: 1, 2, 4, 7 and 24 h (adsorption test)
- Sample storage before analysis: Not reported

Details on matrix:

COLLECTION AND STORAGE
- Geographic location: The Netherlands, a temperate climate zone (Three different soil types were obtained)
- Collection procedures: Not reported
- Sampling depth: 2 m
- Storage conditions: Ambient (room) temperature
- Storage length: Not reported
- Soil preparation: The soils were sieved (2 mm) and coarse particles, debris and plant remnants were removed. The sieved soils were air-dried.

PROPERTIES
Soil Number: 545070 (8001450710)
- Soil texture: Not reported
- % sand: Not reported
- % silt: Not reported
- % clay: 3.2
- Horizon: Not reported
- Soil taxonomic classification: Not reported
- Soil classification system: Not reported
- Soil series: Not reported
- Soil order: Not reported
- pH ( CaCl2): 6.1
- Organic matter content (%): 2.7
- CEC (meq/100 g): Not reported
- Carbonate as CaCO3: Not reported
- Insoluble carbonates (%): Not reported
- Extractable Cations (Ca, Mg, Na, K, H) (MEQ/100 g): Not reported
- Special chemical/mineralogical features: Not reported
- Clay fraction mineralogy: Not reported
- Moisture at 1/3 atm (%): Not reported
- Bulk density (g/cm3): Not reported
- Biomass (e.g. in mg microbial C/100 mg, CFU or other): Not reported

Soil Number: 543151 (8001450711)
- Soil texture: Not reported
- % sand: Not reported
- % silt: Not reported
- % clay: 11
- Horizon: Not reported
- Soil taxonomic classification: Not reported
- Soil classification system: Not reported
- Soil series: Not reported
- Soil order: Not reported
- pH ( CaCl2): 4.6
- Organic matter content (%): 0.8
- CEC (meq/100 g): Not reported
- Carbonate as CaCO3: Not reported
- Insoluble carbonates (%): Not reported
- Extractable Cations (Ca, Mg, Na, K, H) (MEQ/100 g): Not reported
- Special chemical/mineralogical features: Not reported
- Clay fraction mineralogy: Not reported
- Moisture at 1/3 atm (%): Not reported- Bulk density (g/cm3): Not reported
- Biomass (e.g. in mg microbial C/100 mg, CFU or other): Not reported

Soil Number: 545347(8001450712)
- Soil texture: Not reported
- % sand: Not reported
- % silt: Not reported
- % clay: 24
- Horizon: Not reported
- Soil taxonomic classification: Not reported
- Soil classification system: Not reported
- Soil series: Not reported
- Soil order: Not reported
- pH ( CaCl2): 7.9
- Organic matter content (%): 2.6
- CEC (meq/100 g): Not reported
- Carbonate as CaCO3: Not reported
- Insoluble carbonates (%): Not reported
- Extractable Cations (Ca, Mg, Na, K, H) (MEQ/100 g): Not reported
- Special chemical/mineralogical features: Not reported
- Clay fraction mineralogy: Not reported
- Moisture at 1/3 atm (%): Not reported
- Bulk density (g/cm3): Not reported
- Biomass (e.g. in mg microbial C/100 mg, CFU or other): Not reported

Details on test conditions:

TEST CONDITIONS
- Buffer: Not reported
- pH: 5.59 (Soil 8001450710), 4.58 (Soil 8001450711), 6.70 (Soil 8001450712)
- Suspended solids concentration: Not reported

TEST SYSTEM
- Type, size and further details on reaction vessel: 100 mL glass centrifuge tube, closed with a screw cap containing 50 mL aqueous phase and 10 g soil.
- Water filtered: No. The dry weight percentage of unsieved soils prior to air-drying was 84% (soil 543151), 93% (soil 545070), and 81 % (soil 545347). Air drying of sieved soils had reduced the moisture content considerably, therefore the contribution of residual water was considered of minor or negligible effect.
- Amount of soil/sediment/sludge and water per treatment: 10 g soil
- Soil/-water ratio: 1:5 w/w
- Number of reaction vessels/concentration: Two
- Measuring equipment: Not reported
- Test performed in closed vessels due to significant volatility of test substance: Yes
- Method of preparation of test solution: A stock test solution of ca. 1.17 g/L of the test substance (TSIN GTS02902) was prepared by accurately weighing approximately 36.6 mg test substance in 10 mL ethanol/water (1:9 v/v). A test solution of approximately 80 mg/L TSIN GTS02902 was prepared by dilution of 342 µL stock solution to 5 mL with a 0.01 mol/L CaCI2 solution in Suprapur® water. A test solution of approximately 200 mg/L TSIN GTS02902 was prepared by dilution of 3 mL stock solution to 17.55 mL with a 0.01 mol/L CaCI2 solution in Suprapur® water.
- Are the residues from the adsorption phase used for desorption: No
- Other:
- Preparation of calcium chloride solution
A 0.01 mol/L calcium chloride (CaCI2 ) solution was prepared by dissolving 1.11 grams of CaCI2.2H2O (Merck, Darmstadt, Germany, lot 315TA456782) in 1 liter of Suprapur® water.
- Adsorption test
For all three soil types, duplicate test systems were prepared with 49 mL 0.01 mol/L CaCl2 solution in Suprapur® water and 10 g of soil. Blank test systems were prepared by adding 50 mL 0.01 mol/LCaCl2 solution in Suprapur® water to soil numbers 545070 and 54315. Duplicate soilless controls were also included in the test.
After pre-equilibration at the test temperature over the week-end, the test systems (except blanks) were fortified at time zero (t =0) with the test substance by adding 1 mL of 200 mg/L TSIN# GTS02902 test solution to the aqueous phase.
Agitation was begun immediately after fortification and after 1, 2, 4, 7 and 24 h of equilibration; an aliquot of 100 µL aqueous phase was removed for analysis. The decrease in volume of the aqueous phase remaining in the test systems was considered negligible.
The pH of the test solutions was accurately measured at approximately t = 72 h, according to relevant Analytico Medinet SOP (OPOOO3NL) to a precision of at least 0.1 pH unit using a calibrated pH meter.

Sample No.:

#1

Duration:

7 h

Initial conc. measured:

4 004 other: µg/L; Soil No. 8001450710 (545070)

pH:

5.59

Temp.:

23.6 °C

Sample No.:

#2

Duration:

7 h

Initial conc. measured:

4 004 other: µg/L; Soil No. 8001450711 (543151)

pH:

4.58

Temp.:

23.6 °C

Sample No.:

#3

Duration:

7 h

Initial conc. measured:

4 004 other: µg/L; Soil No. 8001450712 (545347)

pH:

6.7

Temp.:

23.6 °C

Computational methods:

- Adsorption and desorption coefficients (Kd):
Kd = Cs(eq)/ Caq (eq)
Caq(eq) = concentration (µg/L) of the test substance remaining in the aqueous phase at equilibrium corrected for the soilless control
Cs(eq) = content of test substance adsorbed onto soil at equilibrium (µg/kg); which is in formula
Cs (eq) = V X (C soilless control-C (eq)/1000)/m in which ‘V’ is the volume (mL) of aqueous phase of the test systems and m the amount (kg) of soil employed.
- Adsorption coefficient per organic carbon (Kom): The adsorption coefficient related to the soil organic matter (om) content (Kom, liter/kilogram) was also calculated:
Kom = (Kd * 100%)/% Organic matter (om)

Type:

Kd

Value:

8.3

Temp.:

23.6 °C

% Org. carbon:

2.7

Remarks on result:

other: C12 homologue (soil 545070)

Type:

Kd

Value:

> 16.9

Temp.:

23.6 °C

% Org. carbon:

0.8

Remarks on result:

other: C12 homologue (soil 543151)

Type:

Kd

Value:

> 16.1

Temp.:

23.6 °C

% Org. carbon:

2.6

Remarks on result:

other: C12 homologue (soil 545347)

Type:

Koc

Value:

307

Temp.:

23.6 °C

% Org. carbon:

2.7

Remarks on result:

other: C12 homologue (soil 545070)

Type:

Koc

Value:

> 2 113

Temp.:

23.6 °C

% Org. carbon:

0.8

Remarks on result:

other: C12 homologue (soil 543151)

Type:

Koc

Value:

> 619

Temp.:

23.6 °C

% Org. carbon:

2.6

Remarks on result:

other: C12 homologue (soil 545347)

Adsorption and desorption constants:

For details on the adsorption values, please refer Table 1. under section ‘Any other information on results incl. tables’
Desorption constants were not measured in the study.

Recovery of test material:

- 0.01 mol/L CaCl2 solution in Suprapur® water + 4006 µg/L TSIN GTS02902 (Soilless control): 98.5% for C12-homologue and 76.7% for C14-homologue
- Soil extract 8001450712 + 4006 µg/L TSIN GTS02902: 97.9% for C12 homologue and 59.0 % for C14-homologue
- Recoveries of TSIN GTS02902 C12- and C14-homologue in the soilless were ranging from 94.3 to 114% and 90 to 119%, respectively

Concentration of test substance at end of adsorption equilibration period:

C12 homologue: For soil No. 8001450710 = 1536; 8001450711 = <1000 (467); 8001450712 = <1000 (838)
C14 homologue: For soil No. 8001450710 = <1000 (779); 8001450711 = 1109; 8001450712 = <1000(496)
Values in the bracket: The measured concentrations in the aqueous phases were below the detection limit, i.e. < 1000 µg/L

Transformation products:

not measured

Details on results (Batch equilibrium method):

PRELIMINARY TEST
- Sample purity: Not reported
- Weighed soil: 10 g
- Volume of CaCl2 solution: 49 mL of 0.01 mol/L CaCl2 solution in Suprapur® water
- Initial test substance concentration: 200 mg/L
- Test substance concentration in final solution: 4004 µg/L
- Analytical test substance concentration in final solution:
C12 homologue: 8001450710=1536; 8001450711=<1000 (467); 8001450712:<1000 (838)
C14 homologue: 8001450710= <1000(779); 8001450711= 1109; 8001450712: <1000(496}
Other:

MAIN TEST: PERFORMANCE
- Test material stability during adsorption/desorption phase: Stable
- Experimental conditions maintained throughout the study: Yes
- Buffer/test substance interactions affecting sorption: Not applicable
- Further chemical interactions: Not applicable
- Buffer: Not applicable
- Catalyzed degradation of test substance: Not applicable

TRANSFORMATION PRODUCTS: not measured.

RESIDUES: not measured

VOLATILIZATION: not measured

Statistics:

Not reported

Table 1. Results of the adsorption test at equilibrium for the C12 and C14 homologue of amine oxide (TSIN# GTS02902) (Study# 52865)

Soil Type	C12 homologue		C14 homologue
	Mean adsorption coefficient Kd(L/kg)	Mean adsorption coefficient related to the soil organic matter Kom (L/kg)	Mean adsorption coefficient Kd(L/kg)	Mean adsorption coefficient related to the soil organic matter Kom (L/kg)
8001450710 (soil 545070)	8.3	307	>16.8	>622 (906)
8001450711 (soil 543151)	>16.9 (56.1)	>2113	>15.8	>1969 (2151)
8001450712 (soil 545347)	>16.1 (18.3)	>619	>16.8	>646 (1281)

K values between brackets are calculated using the actual measured concentrations below the detection limit yet they provide reliable values of K.

Adsorption equilibrium was obtained after 7 h of incubation.

Validity criteria fulfilled:

not applicable

Conclusions:

The adsorption behaviour of C12/14 alkyl dimethyl amine oxide was determined in three different soil types. The mean adsorption coefficient (Kd) for soil 5545070, soil 543151 and soil 545347 was 8.3, >16.9, and >16.1 L/kg, respectively. The mean adsorption coefficient related to the soil organic matter (Kom), for soil 5545070, soil 543151 and soil 545347 was 307, >2113, and >619 L/Kg, respectively.

Executive summary:

The adsorption coefficient study of C12/14 alkyl dimethylamine oxide was determined in three different soil types, following OECD 106 guideline. Two homologues (C12 and C14) of the test material were evaluated for adsorption in the study.

Good reproducibility was obtained between the duplicates in the adsorption test. For all three soil types, adsorption equilibrium was reached at 7 h of incubation. The applied soil:solution ratio was 1:5. The test material adsorbed well onto the three soil types with adsorption percentages in the range of 68 - 100% after 7 h of equilibration. Reversibility of the adsorption process (desorption) was evaluated in this study.

The recovery of the duplicate soilless control solutions was 109 and 110 % for the C12-homologue and 109% (2x) for the C14 homologue at equilibrium (7 hrs), indicating no adsorption onto the container occurred. No matrix effect of the soil onto analytical results was observed for the measurement of test material in aqueous phase after equilibration of 0.01 M CaCI2 solution in Suprapur® water with soil number 545347. Results of the blanks were therefore not taken into account when calculating the results for the test substance.

The influence of soil on the pH of the aqueous phase was in the range of approximately 0.2 to 1.3 pH unit.

The mean adsorption coefficient (Kd) for soil 5545070, soil 543151, and soil 545347 was 8.3, >16.9, and >16.1 L/kg, respectively. The mean adsorption coefficient related to the soil organic matter (Kom), for soil 5545070, soil 543151, and soil 545347 was 307, >2113, and >619 L/Kg, respectively. This adsorption test is classified as acceptable, and satisfies the guideline requirements for the OECD 106.

Description of key information

The adsorption of C12-14 AO in three soil types was determined according to OECD TG 106. Kom values were obtained for C12 and C14 homologues, converted to Koc and these values were used to calculate Kd values normalised to 2 % organic carbon. The geometric mean of the Kd values was used to calculate the Koc for C12-14 AO of 1525 L/kg.

Key value for chemical safety assessment

Koc at 20 °C:

1 525

Additional information

The adsorption of C12-14 AO in three soil types was determined in a GLP study according to OECD TG 106 [Van de Ruit (2002)]. The soil types used were obtained from various locations in the Netherlands. Organic matter/clay contents of the three soils (labelled 545070, 543151 and 545347) were 2.7 %/3.2 %, 0.8 %/11 % and 2.6 %/24 % respectively.Two homologues (C12 and C14) of the test material were evaluated for adsorption in the study (desorption was not tested). The applied soil : solution ratio was 1:5. For all three soil types, adsorption equilibrium was reached at 7 h of incubation. Adsorption percentages were in the range of 68 - 100% after this time.

The recovery of the duplicate soiless control solutions was 109 and 110 % for the C12-homologue and 109% (2x) for the C14 homologue at equilibrium (7 hrs), indicating no adsorption onto the container occurred. No matrix effect of the soil onto analytical results was observed for the measurement of test material in aqueous phase after equilibration of 0.01 M CaCI2 solution in Suprapur® water with soil number 545347. Results of the blanks were therefore not taken into account when calculating the results for the test substance. The influence of soil on the pH of the aqueous phase was in the range of approximately 0.2 to 1.3 pH unit.

The mean adsorption coefficient (Kd) for soil 5545070, soil 543151, and soil 545347 was 8.3, >16.9 (56.1), and >16.1 (18.3) L/kg, respectively for the C12 homologue and >16.8 (24.5), >15.8 (17.2) and >16.8 (33.3) for the C14 homologue. The mean adsorption coefficient related to the soil organic matter (Kom), for soil 5545070, soil 543151, and soil 545347 was 307, >2113 (7013), and >619 (702) L/Kg, respectively for the C12 homologue and >622 (906), >1969 (2151) and >646 (1281) for the C14 homologue.

In order to calculate the Koc value for use in the exposure assessment, Kom values were converted into Koc values using the relationship soil organic matter = 1.724 x soil organic carbon content.The Kom value for the C12 homologue in soil 543151 was excluded from calculations as a suspected outlier due to the low percentage organic carbon of the soil type used, which may limit correlation with organic carbon content, and since the data failed to correlate with the increased affinity for soils anticipated to be demonstrated by the C14 homologue. The Koc values were then used to calculate the theoretical distribution coefficient Kd normalised to 2% organic carbon. The geometric mean of the Kd values was calculated as 46.8 L/kg, equivalent to a Koc of 1525 L/kg.

[LogKoc: 3.18]