E17-194T, (P,P-diethyl, monoester with 1,2 propanediol)_

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:

Jun 2020 - May 2021

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:

no

GLP compliance:

yes (incl. QA statement)

Type of method:

batch equilibrium method

Media:

soil

Specific details on test material used for the study:

17-194T, Lot #: 300567-78-7
Composition: P,P-diethyl, monoester with 1,2 propanediol - 92.9%, CAS #2230512-72-6
Physical Description: Clear, transparent liquid
pH: Neutral to slightly acidic
Stability: Test substance was expected to be stable for the duration of testing.
Expiration Date: aug 30, 2022

Radiolabelling:

no

Test temperature:

25 oC

Analytical monitoring:

yes

Details on sampling:

- Sampling interval: Samples of 0.3 mL were taken at 2, 4, 6, 21.5, 45.3, 68.5 and 141.9 hours for soil 1 and 2, not autoclaved as no equilibration was achieved. Samplings were performed for the auto-claved soils soils 3,4 and 5 at 2, 4, 6, 24 and 48 hours.
- Sample storage before analysis:no

Matrix no.:

#1

Matrix type:

sandy loam

% Clay:

8.9

% Silt:

13.9

% Sand:

77.2

% Org. carbon:

2.12

pH:

>= 5.46

CEC:

8.5 meq/100 g soil d.w.

Bulk density (g/cm³):

1.232

Matrix no.:

#2

Matrix type:

clay

% Clay:

41.2

% Silt:

35.5

% Sand:

23.3

% Org. carbon:

1.46

pH:

7.33

CEC:

23.2 meq/100 g soil d.w.

Bulk density (g/cm³):

1.299

Matrix no.:

#3

Matrix type:

silt loam

% Clay:

23.9

% Silt:

60.6

% Sand:

15.5

% Org. carbon:

5.04

pH:

5.53

CEC:

17.3 meq/100 g soil d.w.

Matrix no.:

#4

Matrix type:

clay

% Clay:

75

% Silt:

21.9

% Sand:

3.3

% Org. carbon:

3.08

pH:

5.3

CEC:

28.32 meq/100 g soil d.w.

Matrix no.:

#5

Matrix type:

loamy sand

% Clay:

6

% Silt:

12.6

% Sand:

81.6

% Org. carbon:

7.35

pH:

2.98

CEC:

6.12 meq/100 g soil d.w.

Details on test conditions:

Tier 1
In the preliminary test, the optimal soil/solution ratio was determined. The air-dried soil samples were shaken with 30 mL (blanks) resp. 27 mL of a 0.01 M CaCl2-solution over-night. 3 mL of test item stock solution (nominal concentration 5000 mg/L) was added to all 27 mL preparations to result in a test item solution with nominal concentration 100 mg/L. The following soils were used in tier 1: Refesol 03-G (S3) and Soil Eurosoil 5 (S5); with the ratios: 1.1 : 1; 1 : 1 and 0.7 : 1 for soil 3 resp. 1.2 : 1, 1 : 1 and 0.7 : 1 for soil 5.
One blank per soil and ratio with soil and CaCl2 solution (without test item) was prepared in order to determine the background signal.
Two adsorption control samples with the test item in CaCl2 solution (without soil) were included in order to check the stability of the test item in CaCl2 and the adsorption on the vessel surface.
The final volume of the aqueous phase was 30 mL for all ratios.

Tier 2
30 g of the air-dried soil samples were shaken with 30 mL resp. 27 mL of a 0.01 M CaCl2-solution overnight. 3 mL of test item stock solution (nominal concentration 5000 mg/L) was added to all 27 mL approaches to result in a test item solution with nominal concentration 500 mg/L.
Additionally, one blank per soil was prepared for the determination of the background signal, and two adsorption controls containing test item and CaCl2 solution were prepared for the determination of stability and adsorption on the vessel surface.
The final volume of the aqueous phase was 30 mL for all preparations.

Sample No.:

#1

Duration:

48 h

Initial conc. measured:

500 other: mg/L

pH:

6.09

Temp.:

>= 24.2 - <= 24.9 °C

Remarks:

Nominal concentrations t0 are reported

Sample No.:

#2

Duration:

48 h

Initial conc. measured:

500 other: mg/L

pH:

7.36

Temp.:

>= 24.2 - <= 24.9 °C

Remarks:

Nominal concentrations t0 are reported

Sample No.:

#3

Duration:

48 h

Initial conc. measured:

500 other: mg/L

pH:

5.85

Temp.:

>= 25 - <= 25.1 °C

Remarks:

Nominal concentrations t0 are reported

Sample No.:

#4

Duration:

48 h

Initial conc. measured:

500 other: mg/L

pH:

5.44

Temp.:

>= 25 - <= 25.1 °C

Remarks:

Nominal concentrations t0 are reported

Key result

Sample No.:

#1

Type:

Koc

Value:

1.49 L/kg

Key result

Sample No.:

#2

Type:

Koc

Value:

5.92 L/kg

Key result

Sample No.:

#3

Type:

Koc

Value:

1.41 L/kg

Key result

Sample No.:

#4

Type:

Koc

Value:

8.79 L/kg

Transformation products:

not measured

Remarks:

Biodegradation is presented in the not autoclaved soils. the the soils wre autoclaved

Validity criteria fulfilled:

yes

Conclusions:

No values of Kd, multiplied with the soil-solution-ratio, resulted in a value of > 0.3 cm3/g (rounded values). Therefore, tier 3 was not determined. KOC  was determined with 1.28 – 8.79 cm3/g.
Apparently, the adsorption behaviour of the test item is not strictly correlated with the or-ganic carbon content of the respective soil.
It is concluded, that only the soils with high clay content showed KOC values >2, whereby the adsorption is probably mainly caused by the clay content and not by the content of or-ganic carbon

Description of key information

Apparently, the adsorption behaviour of the test item is not strictly correlated with the organic carbon content of the respective soil.

The highest K_OCvalue was obtained with Eurosoil 1 (clay content 75%), the next highest K_OCvalue was obtained with soil Lufa 6S (clay content 41.2%). Soils with high content of clay can adsorb a higher content of humus, and clay-humus compexes occur. These complexes are able to adsorb polar organic substances.

It is concluded, that only the soils with high clay content showed K_OCvalues >2, whereby the adsorption is probably mainly caused by the clay content and not by the content of organic carbon

Key value for chemical safety assessment

Koc at 20 °C:

5.29