acetalization product between glucose and C16-18(even numbered)- alcohol

Adsorption / desorption

Link to relevant study record(s)

Reference

Endpoint:

adsorption / desorption, other

Type of information:

experimental study

Adequacy of study:

key study

Study period:

09/07/2013 - 12/09/2014

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: The study was conducted according OECD guideline 106 and in compliance with the Good Laboratory Practice (GLP).

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

Radiolabelling:

no

Test temperature:

All the experiments were performed at laboratory ambient temperature (temperature between 20°C and 25°C).

Analytical monitoring:

yes

Details on sampling:

Adsorption Kinetic:
The samples were collected sequentially at 0.5, 1, 2, 4 and 6 hours for five soils.
Freundlich Adsorption Isotherm The samples were collected at equilibrium time (0.5 hour) for the five soils.
Desorption Kinetic:
The samples were collected sequentially at 0.5, 1, 2, 4 and 6 hours.
Freundlich Adsorption Isotherm The samples were collected at equilibrium time (0.5 hour) for the five soils.

Details on matrix:

The supplier of soils is LUFA SPEYER located in Germany. Five soils were used:
- Soil n°2.1: Sand [pH 5.1; organic carbon 0.65 %; clay particule size <0.002 mm: 2.8 %],
- Soil n°2.2: Loamy sand [pH 5.5; organic carbon 1.77 %; clay particule size <0.002 mm: 7.3 %],
- Soil n°2.3: Sandy loam [pH 6.8; organic carbon 0.94 %; clay particule size <0.002 mm: 8.5 %],
- Soil n°2.4: Loam [pH 7.2; organic carbon 2.26 %; clay particule size <0.002 mm: 25.9 %]
- Soil n°6S: Clay [pH 7.1; organic carbon 1.64 %; clay particule size <0.002 mm: 40.5 %].

Details on test conditions:

Tier 1 - Preliminary study

The soil samples was equilibrated by shaking with a minimum volume of 45 mL of 0.01 M CaCl2 overnight (12h) before the day of experiment. Afterwards, a certain volume of the stock solution of the test item was added in order to adjust the final volume at 50 mL. This volume of the stock solution added should preferably result in an initial concentration of the test item being with the soil (C0: 10 mg/L (initial concentration)) at least two orders of magnitude higher than the detection limit of the analytical method. The mixture was shaken until adsorption equilibrium was reached. The samples were collected sequentially over a 48 h period of mixing (3, 6, 24, 48h). Then, the samples were separated by centrifugation, the aqueous phase was analysed according to the validated method. One control sample with only the test item in 0.01 M CaCl2 solution (no soil) was subjected to precisely the same steps, in order to check the stability of the test item in CaCl2 solution and its possible adsorption on the surfaces of the tests vessels. A blank run per soil with the same amount of soil and total volume of 50 mL 0.01 M CaCl2 solution (without test item) was subjected to the same procedure. This serves as a background control during the analysis to detect interfering compounds. The pH of the aqueous phase was measured before and after contact with the soil. All the experiments, including controls and blanks were performed in duplicate. The mass balance was performed on both soils and for one soil/solution ratio 1:5 (w:v) after the ratio-finding experiment is completed (measurement of depletion in solution more than 20% at equilibrium). After 48h of equilibrium, the phases were separated by centrifugation and the test item concentration in the aqueous phase was determined. The amount of test item absorbed to the soil was measured after two extractions with a mixture of solvents ( Hexan: Aceton (50:50)(v:v). Then, the extracts were quantified according to the validated method by GC/FID. The data was calculated with the calibration curve using for the chemical analysis of test item in aqueous phase. The quantity of test item in the soil and aqueous phase was determined and the mass balance was calculated. If the mass balance of the test item is less than 90%, the test item is considered to be unstable in the time scale of test which will have to be taken into account for the following tests. The percentage adsorption was calculated at each time on the basis of the nominal initial concentration and the measured concentration at the sampling time corrected for the value of the blank if relevant. Plots of the percentage adsorption versus time were performed in order to estimate the achievement of equilibrium plateau. The Kd value at equilibrium was also calculated. Based on this Kd value, appropriate soil/solution ratios was selected, so the percentage adsorption reaches above 20 %.


Tier 2 - Adsorption kinetics at one concentration

The soil samples were equilibrated by shaking with a minimum volume of 45 mL of 0.01 M CaCl2 overnight (12h) before the day of experiment. Following pre-equilibration, the samples with and without soil were spiked with the test item at a nominal concentration of 10 mg/L and shaken for 6 hours until adsorption equilibrium was reached. The samples were collected sequentially at 0.5, 1, 2, 4 and 6 hours. Then, the samples were separated by centrifugation and then, the aqueous phase was analysed according to the validated method by GC/FID. One control sample with only the test item in 0.01 M CaCl2 solution (no soil) was subjected to precisely the same steps, in order to check the stability of thetest item in CaCl2 solution and its possible adsorption on the surfaces of the tests vessels. A blank run per soil with the same amount of soil and total volume of 50 mL 0.01 M CaCl2 solution (without test item) was subjected to the same procedure. This serves as a background control during the analysis to detect interfering compounds. The pH of the aqueous phase was measured before and after contact with the soil. All the experiments, including controls and blanks were performed in duplicate. The percentage adsorption was calculated at each time on the basis of the nominal initial concentration and the measured concentration at the sampling time corrected for the value of the blank if relevant. Plots of the percentage adsorption versus time were performed in order to estimate the achievement of equilibrium plateau. The distribution coefficient Kd value at equilibrium, as well as the organic carbon normalized adsorption coefficient Koc (for non-polar organic chemicals) were also calculated.


Tier 3 - Adsorption isotherm and desorption kinetics/desorption isotherms

Adsorption isotherms

The Freundlich adsorption isotherms were determined for 5 test item concentrations (0 .25 mg/L – 1 mg/L – 2.5 mg/L – 5 mg/L and 10 mg/L) at a constant soil/solution ratio (1:100), at adsorption equilibrium (0.5 hour ) and for five soils. The adsorption test was performed as follow with the only difference that the aqueous phase was analysed only once at the time necessary to reach equilibrium as determined before tier 2.
The soil samples were equilibrated by shaking with a minimum volume of 45 mL of 0.01 M CaCl2 overnight (12h) before the day of experiment. Afterwards, a certain volume of the stock solution of the test item was added in order to adjust the final volume at 50 mL.
The mixture was shaken during 0.5 hour (adsorption equilibrium). The samples were collected and separated by centrifugation and then, the aqueous phase was analysed according to the validated method.

The equilibrium concentrations in the solution were determined and the amount was calculated from the depletion of the test item in the solution.
The adsorbed mass per unit mass of soil was plotted as a function of the equilibrium concentration of test item.
One control sample with only the test item in 0.01 M CaCl2 solution (no soil) was subjected to precisely the same steps, in order to check the stability of the test item in CaCl2 solution and its possible adsorption on the surfaces of the tests vessels. A blank run per soil with the same amount of soil and total volume of 50 mL 0.01 M CaCl2 solution (without test item) were subjected to the same procedure. This serves as a background control during the analysis to detect interfering compounds.
The pH of the aqueous phase was measured before and after contact with the soil.
All the experiments, including controls and blanks were performed in duplicate and at laboratory ambient temperature (temperature between 20°C and 25°C). The temperature was recorded during the experiments.

Desorption Kinetics

Five soils were used and selected. (Standard soil type no. 2.1 ‘sand ; 2.2 loamy sand; 2.3 sandy loam; 2.4 loam ; 6S clay).
The equilibration time (0.5 hour), the soil /solution ratio (1:100), the weight of the soil sample (0.5g), the volume of the aqueous phase in contact with soil (50 cm3) and the concentration of the test item in the solution (10 µg/cm3) were chosen based on the Tier 2 results.
The soil samples were equilibrated by shaking with a minimum volume of 45 mL of 0.01 M CaCl2 overnight (12h) before the day of experiment. Afterwards, a certain volume of the stock solution of the test item was added in order to adjust the final volume at 50 mL. The mixture was shaken during 0.5 hour (adsorption equilibrium). The samples were separated by centrifugation, then the aqueous phases were removed as much as possible and were replaced by the same amount of fresh 0.01 M CaCl2 without test item and the new mixtures will be agitated again. The samples were collected sequentially over a 24 h period of mixing (0.5, 1, 2, 4 and 6 hours) until the desorption equilibrium was reached. Then, the samples were separated by centrifugation and then, the aqueous phase was analysed according to the validated method.
One control sample with only the test item in 0.01 M CaCl2 solution (no soil) was subjected to precisely the same steps, in order to check the stability of the test item in CaCl2 solution and its possible adsorption on the surfaces of the tests vessels.
A blank run per soil with the same amount of soil and total volume of 50 mL 0.01 M CaCl2 solution (without test item) was subjected to the same procedure. This serves as a background control during the analysis to detect interfering compounds.
All the experiments, including controls and blanks were performed in duplicate and at laboratory ambient temperature (temperature between 20°C and 25°C). The temperature was recorded during the experiments.
The percentage desorption was calculated at each time point and plotted versus time and the desorption coefficient Kdes at equilibrium was also calculated.
Common plots of the percentage desorption D and adsorption A versus time allowed estimation of the reversibility of the adsorption process. If the desorption equilibrium is attained even within twice the time of the adsorption equilibrium, and the total desorption is more than 75% of the amount adsorbed, the adsorption is considered to be reversible.

Desorption isotherms

Freundlich desorption isotherms were determined on the soils used in the adsorption isotherms experiment. Desorption Kinetics with the difference that the test item was performed at different concentrations and that the aqueous phase was analysed only once, at desorption equilibrium. The amount of test item desorbed was calculated. The content of test item remaining adsorbed on soil at desorption equilibrium was plotted as a function of the equilibrium concentration of the test item in solution. All the experiments, including controls and blanks were performed in duplicate and at laboratory ambient temperature (temperature between 20°C and 25°C). The temperature was recorded during the experiments.

Type:

Kd

Value:

>= 1 147.9 - <= 2 744.5

Temp.:

20 °C

% Org. carbon:

>= 0.65 - <= 2.26

Remarks on result:

other: The Kd range of the Acetalization product between glucose and C16/18 (even numbered) – alcohol is 1147.9 to 2744.5 depending on the soil (All the experiments were performed in duplicate at laboratory ambient temperature (temperature between 20°C to 25°).

Type:

Koc

Value:

>= 50 792 - <= 371 369

Temp.:

20 °C

% Org. carbon:

>= 0.65 - <= 2.26

Remarks on result:

other: The Koc range of the Acetalization product between glucose and C16/18 (even numbered) – alcohol is 50792 to 371369 depending on the soil. (All the experiments were performed in duplicate at laboratory ambient temperature (temperature between 20°C to 25°).

Type:

log Koc

Value:

>= 4.71 - <= 5.57

Temp.:

20 °C

% Org. carbon:

>= 0.65 - <= 2.26

Remarks on result:

other: Log Koc range of the Acetalization product between glucose and C16/18 (even numbered) – alcohol is 4.71to 5.57 depending on the soil (All the experiments were performed in duplicate at laboratory ambient temperature (temperature between 20°C to 25°).

Transformation products:

no

Adsorption Kinetic

The tables below summarize the results of Kd, Koc and Log Koc for the five soils

 Matrice

       Soil 6S (Clay)

       Soil 2.1 (Sand)

 

 Kd

 % OC

 Koc

 Log Koc

Kd

 % OC

 Koc

 Log Koc

 C16 Alcohol

 1860.9

 1.64

113470

 5.05

 2413.9

 0.65

 371369

 5.57

 C18 Alcohol

 1389.4

 1.64

 84720

 4.93

 1917.9

 0.65

 295062

 5.47

 

 Matrice

       Soil 2.2 (Loamy sand)

       Soil 2.3 (Sandy loam)

 

 Kd

 % OC

 Koc

 Log Koc

 Kd

 % OC

 Koc

 Log Koc

 C16 Alcohol

 2069.6

 1.77

 116927

 5.07

 2744.5

 0.94

 291968

 5.47

 C18 Alcohol

 1607.9

 1.77

 90842

 4.96

 1764.4

 0.94

 187702

 5.27

 

 Matrice

       Soil 2.4 (Loamy )

 

 Kd

 % OC

 Koc

 Log Koc

 C16 Alcohol

 1644.0

 2.26

 72743

 4.86

 C18 Alcohol

 1147.9

 2.26

 50792

 4.71

 

For the glucosides and for all soils, no kinetic curve obtained because these compounds were strongly adsorbed in soils as the alcohol and they do not have the same sensivity in GC/FID compared to alcohols. Nevertheless, in view of results, the C16 mono- and di- glucosides had the same behaviour that the alcohols. 

The four compounds C16 alcohol, C18 alcohol, C16 monoglucoside and C16 diglucoside were strongly adsorbed saturating the soil from 0.5 hour of exposure.

Consequently, for the Tier 3 - Adsorption Isotherm, the time at 0.5 hour of exposure was taken as equilibrium time with a soil:solution ratio 1:100

The Log Koc range of the Acetalization product between glucose and C16/18 (even numbered) – alcohol is 4.71 to 5.57 depending on the soil.

 

Freundlich adsorption isotherm

No Freundlich adsorption isotherms were obtained for C16 Alcohol, C18 Alcohol, C16 monoglucoside and C16 Diglucoside in all soils and the analytical measures indicates mainly contents inferior to LOQ or No detected.

In the range concentration studied, the following compounds C16 Alcohol, C18 Alcohol, C16 monoglucoside and C16 Diglucoside were strongly adsorbed in the 5 soils.

This suggests that the end points determined at this step for Alcohol and Glucoside can be extrapolate to the test Item itself “Acetalization product between glucose and C16/18 (even numbered)” and those for all soils.

In conclusion, the test item “Acetalization product between glucose and C16/18 (even numbered) adsord strongly in all the soils.

 

Desorption Kinetic

The table below summarizes the results of Kdes for the five soils

 Matrice

 Clay

 Sand

 Loamy sand

 Sandy Loam

 Loam

 

 Kdes (cm3.g-1)

 Kdes (cm3.g-1)

Kdes (cm3.g-1) 

 Kdes (cm3.g-1)

 Kdes (cm3.g-1)

 C16 Alcohol

 958

3137

476

433

308

 C18 Alcohol

 718

2609

384

344

234

 

The percentage of desorption ranged from 4.87 - 13.52 %, 1.22 - 3.82 %, 2.89 – 22.69 %, 7.66 – 31.26 % for the clay, sand, loamy sand, sandy loam and loam soils, respectively for C16 alcohol and C18 alcohol during the desorption kinetic.

In view of C^des_aq(ti) values obtained during the desorption kinetics for C16 monoglucosidel and C16 diglucoside in comparaison with the Alcohols, the desorption profile are similar and can be extrapolated to Alcohols.

 The adsorption of the Acetalization product between glucose and C16/18 (even numbered) – alcohol is considered to be irreversible in all soils.

The Kdes range of the Acetalization product between glucose and C16/18 (even numbered) alcohol is 234 to 3137 depending on the soil.

 

 

Freundlich Desorption Isotherm

For the C16 Alcohol, C18 Alcohol, C16 monoglucoside and C16 diglucoside, no Freundlich desorption isotherm was obtained in all test soils because the adsorption isotherm did not allow to obtain C^ads_aq(eq) values for the concentrations studied at the equilibrium of adsorption or C^des_aq (eq) values obtained in desorption isotherm were inferior to LOQ or No detected.

Regarding the Freundlich Desorption Isotherm , a priori, C16 Alcohol, C18 Alcohol, C16 monoglucoside and C16 diglucoside have a similar desorption profile.

 This suggests that the end points determined at this step for Alcohols and Glucosides can be extrapolated to the test Item itself and those for all the soils.

According to Freundlich Desorption Isotherm, the test item, Acetalization product between glucose and C16/18 (even numbered) – alcohol, is strongly adsorbed in all the soils but desorbs slightly in all the soils.

Validity criteria fulfilled:

yes

Conclusions:

In the conditions of the test, based on the behaviour of four representative compounds of the test UVCB test substance (C16 alcohol, C18 alcohol, C16 monoglucoside and C16 diglucoside), it can be concluded that Acetalization product between glucose and C16/18 (even numbered) - alcohol was strongly adsorbed, saturating the soil from 0.5 hour of exposure. The Log Koc range of the Acetalization product between glucose and C16/18 (even numbered) – alcohol is 4.71 to 5.57 depending on the soil. Based on the FAO mobility classification, the Acetalization product between glucose and C16/18 (even numbered) alcohol was thus considered as hardly mobile to immobile depending on the soil. No Freundlich adsorption isotherms were obtained for C16 Alcohol, C18 Alcohol, C16 monoglucoside and C16 Diglucoside in all soils and the analytical measures indicates mainly contents inferior to LOQ or No detected. In the range concentration studied, the following compounds C16 Alcohol, C18 Alcohol, C16 monoglucoside and C16 Diglucoside were strongly adsorbed in the 5 soils.
For the 5 soils and for all representative compounds, the desorption was less than 75 % of the amount adsorbed. The adsorption was considered to be irreversible for the C16 Alcohol, C18 Alcohol, C16 monoglucoside and C16 Diglucoside. The Kdes range of the Acetalization product between glucose and C16/18 (even numbered) – alcohol was 234 to 3137 depending on the soil.
Therefore, according to the results obtained for adsorption/desorption isotherms of Acetalization product between glucose and C16/18 (even numbered) – alcohol, desorption was lower than adsorption in all the test soils indicating easy and strong adsorption and low desorption.

Executive summary:

The adsorption desorption behaviour of Acetalization product between glucose and C16/18 (even numbered) - alcohol were studied in five different soils, including a sandy soil (Speyer 2.1, 0.65% o.c.), a loamy sand (Speyer 2.2; 1.77% o.c.), a sandy loam (Speyer 2.3; 0.94% o.c.), a loam (Speyer 2.4, 2.26% o.c.) and a clay soil (Speyer 6S; 1.64% o.c.). As the test item was a UVCB composed by different chemical structures, the analytical determinations were performed on four representative constituents: C16 alcohol, C18 alcohol, C16 monoglucoside and C16 diglucoside.

Adsorption/Desorption was studied using the batch equilibrium method (OECD 106, 2000) and calculated as the difference between the initial constituents concentrations and the concentrations at sampling. All experiments were carried out at 20 -25°C.

Based on results of a preliminary test, soil solution ratios of 1:100 was selected for the adsorption and desorption kinetics experiment.

Adsorption and desorption kinetics were determined at an initial concentration of approximately 10 mg/L. After 0.5 hour, equilibrium was reached. For all soils, the adsorption coefficients were based on the Freundlich equation.

The Log Koc range of the Acetalization product between glucose and C16/18 (even numbered) – alcohol is 4.71 to 5.57 depending on the soil.
Based on the FAO mobility classification, the Acetalization product between glucose and C16/18 (even numbered) alcohol was thus considered as hardly mobile to immobile depending on the soil.

No Freundlich adsorption isotherms were obtained for C16 Alcohol, C18 Alcohol, C16 monoglucoside and C16 Diglucoside in all soils and the analytical measures indicates mainly contents inferior to LOQ or No detected. In the range concentration studied, the following compounds C16 Alcohol, C18 Alcohol, C16 monoglucoside and C16 Diglucoside were strongly adsorbed in the 5 soils.

For the 5 soils and for all representative compounds, the desorption was less than 75 % of the amount adsorbed. The adsorption was considered to be irreversible for the C16 Alcohol, C18 Alcohol, C16 monoglucoside and C16 Diglucoside.

The Kdes range of the Acetalization product between glucose and C16/18 (even numbered) – alcohol was 234 to 3137 depending on the soil.

Therefore, according to the results obtained for adsorption/desorption isotherms of Acetalization product between glucose and C16/18 (even numbered) – alcohol, desorption was lower than adsorption in all the test soils indicating easy and strong adsorption and low desorption.

Description of key information

The Koc range of the Acetalization product between glucose and C16/18 (even numbered) – alcohol is 50792 to 371369 depending on the soil. (All the experiments were performed in duplicate at laboratory ambient temperature (temperature between 20°C to 25°) according to the OECD 106.

Key value for chemical safety assessment

Koc at 20 °C:

371 369