Acylation product between cocoyl chloride and aminoacids

Adsorption / desorption

Link to relevant study record(s)

Reference

Endpoint:

adsorption / desorption: screening

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Qualifier:

according to guideline

Guideline:

OECD Guideline 121 (Estimation of the Adsorption Coefficient (Koc) on Soil and on Sewage Sludge using High Performance Liquid Chromatography (HPLC))

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Type of method:

HPLC estimation method

Media:

soil/sewage sludge

Radiolabelling:

no

Test temperature:

The temperature during the analytical phase was around 22°C.

Details on study design: HPLC method:

ANALYTICAL QUANTIFICATION

1. Objective of the test
The objective of the test was to estimate the adsorption/desorption coefficient on soil and on sewage sludge of LCE08116 using (HPLC) High Performance Liquid Chromatography following the test method (OECD Guideline No. 121, 2001).


2. Principle
The adsorption/desorption coefficient is defined as the ratio between the concentration of the test substance in the soil/sludge and the concentration of the test substance in the aqueous phase at adsorption equilibrium.
The adsorption coefficient Koc normalised to the organic carbon of the soil is a useful indicator of the binding capacity of a substance on organic matter of soil or sewage sludge.

Koc = Kd/foc

Where Kd = C soil / C water or C sludge / C water

With C soil, C sludge and C water = Concentration of the substance at equilibrium


3. Experimental procedure
3.1. Principle of the HPLC method
The experimental method uses HPLC for the estimation of the adsorption coefficient Koc in soil and in sewage sludge.
HPLC is performed on a column packed with a cyanopropyl phase containing lipophilic and polar moieties. While passing through the volume along with the mobile phase, the test substance interacts with the stationary phase. The dual-composition of the stationary phase having polar and non-polar sites allows for interaction of polar and non-polar groups of
a molecule in a similar way as is the case for organic matter in soil or sewage sludge matrices. This enable the relationship between the retention time on the column and the adsorption coefficient on organic matter to be established. Cela permet donc d’établir une relation entre le temps de retention et le coefficient d’adsorption de la matière organique.

3.2. Determination of the adsorption/desorption coefficient The adsorption/desorption coefficient is given by the following equation:

log k’ = m log Koc + b

Where k’ is the capacity factor of the chromatographic column ; m and b the coefficient of the calibration curve

The coefficients of the calibration curve are obtained through the chromatographic analysis of at least six analytical reference items with known adsorption coefficient.

3.3. Experimental procedure
The chromatographic determination of the retention time of the analytical reference items and of LCE08116 was done during the study.


4. Analytical method for the adsorption/desorption coefficient determimation
*Reagents:
- Acetone for analysis
- Methanol for HPLC
- Water for HPLC
- All the glassware was rinsed with acetone for analysis and air dried before use.

*Apparatus:
- Autosampler: Hitachi AS2000A
- HPLC pump: Hitachi L-6200A
- UV visible detector: Hitachi L-4250
- Ultrasonic tank: Transonic Type T425H
- Magnetic stirrer: Heidolph 94360
- Balance: Accuracy ± 0.1 mg Mettler AE 100S
- Usual laboratory apparatus

*Safety instructions:
The chemicals, solvents and equipment were used with caution. The safety rules defined within DEFITRACES were strictly followed.

*Preparation of the mobile phase:
A volume of 275 mL of water was transferred into a 500-mL graduated cylinder. A volume of 225 mL of methanol was added. The solution was treated with ultrasounds for 5 minutes and left to stand for 10 minutes before analysis.

* Preparation of the thiourea solution:
The thiourea solution was prepared at a concentration of about 800 mg/L and diluted 100 then 1.5 fold with methanol/eau 5/5 before analysis.
This diluted solution was used for the t0 determination.

*Preparation of the mixed analytical reference item solutions:
Acetanilide, methylbenzoate, isoproturon, 1,2,3-trichlorobenzene, pyrazophos and 4,4’-DDT are the six reference items solutions chosen within the method recommended reference substances for the HPLC method.
Each reference item solution was prepared separately at a concentration of about 100 mg/L (for acetanilide, 1,2,3-trichlorobenzene, pyrazophos, 4,4’-DDT), about 200 mg/L (for isoproturon) and about 800 mg/L (for methylbenzoate) in methanol.

The reference items were mixed and diluted to about 20 mg/L (for 1,2,3-trichlorobenzene, pyrazophos and 4,4’-DDT) and about 5 mg/L (acetanilide, methylbenzoate, isoproturon) for with a mixture of methanol/water 5/5 v/v.
This solution was used as the reference item solution to obtain the calibration curve.

*Preparation of the test item solution:
A quantity of about 100 mg of LCE08116 was accurately weighed into a 100-mL volumetric flask and the volume was made with methanol. The solution was treated with ultrasounds for 5 minutes and left to cool.
The solution was diluted 10 times in methanol and a vial was prepared for analysis.

*Instrumental analysis
The experimental conditions used for the determination of the retention times of the analytical reference items and of the test item by high pressure liquid chromatography equipped with an ultraviolet detector are as following:

*Column
Column: Supelco ; Length (cm) 25
Particle size (μm): 5.0 ; Internal diameter (mm) 4.6
Stationary phase: Supelcosil LC-CN
Mobile phase: Methanol / water 45/55 v/v
Flow rate (mL/min): 0.9
Injected volume (μL): 40 ; Wave length analysis (nm) 210

*Injection sequence
Mixture of the analytical reference items, test item, mixture of the analytical reference items, test item, mixture of the analytical reference items, individual analytical reference items.
The temperature during the analytical phase was around 22°C.

Type:

log Koc

Value:

< 1.25

Temp.:

22 °C

Details on results (HPLC method):

Variation in the retention times of the reference items are very small. Therefore a stable configuration of the HPLC column can be assumed.
The correlation logk’/ log koc is accurate as calibration gave a coefficient of correlation near r2 = 0.965.
Under the normal chromatographic conditions, the test item peak showed nearly no retention on the column and no reference item with lower retention time was available.
Therefore, the log koc of the test item peak must be stated as < 1.25 (lowest value of calibration).

Results
The results of the adsorption coefficient determination of LCE08116 are given in the following tables:
First run:

Products	Mean Retention Time (min)	Value of the Capacity factor k’	Value of log k’	Value of log koc
Acetanilide	4.66	0.28	-0.56	1.25
Methyl benzoate	5.78	0.58	-0.23	1.80
Isoproturon	6.71	0.84	-0.077	1.86
1,2,3-trichlorobenzene	12.30	2.37	0.37	3.16
Pyrazophos	20.19	4.53	0.66	3.65
4,4’ DDT	56.58	14.5	1.16	5.63
Test item	2.28	-	-	< 1.25

Mean t₀ = 3.65 min

Using the Capacity factor and the adsorption coefficient of the reference items, the following calibration curve was obtained: log k’ = 0.384 log k_oc – 0.889 r² = 0.9650

Second run:

Products	Mean Retention Time (min)	Value of the Capacity factor k’	Value of log k’	Value of log koc
Acetanilide	4.66	0.28	-0.55	1.25
Methyl benzoate	5.78	0.58	-0.24	1.80
Isoproturon	6.71	0.84	-0.076	1.86
1,2,3-trichlorobenzene	12.30	2.37	0.37	3.16
Pyrazophos	20.15	4.52	0.66	3.65
4,4’ DDT	56.54	14.5	1.16	5.63
Test item	2.27	-	-	< 1.25

Mean t₀ = 3.65 min

Using the Capacity factor and the adsorption coefficient of the reference items, the following calibration curve was obtained: log k’ = 0.383 log koc – 0.888 r² = 0.9659

Validity criteria fulfilled:

not applicable

Conclusions:

The adsorption / desorption coefficient of the test item is lower then 1.25.

Executive summary:

Determination of the adsorption / desorption coefficient of the test item In compliance with OECD Guideline No. 121 (2001)

The objective of this study was to estimate the adsorption/desorption coefficient on soil and on sewage sludge using (HPLC) High Performance Liquid Chromatography following the test method (OECD Guideline No. 121, 2001).

Using this procedure, it was shown that the adsorption / desorption coefficient of the test item is lower then 1.25.

Description of key information

The objective of this study was to estimate the adsorption/desorption coefficient on soil and on sewage sludge using (HPLC) High Performance Liquid Chromatography following the test method (OECD Guideline No. 121, 2001). Using this procedure, it was shown that the adsorption / desorption coefficient of LCE08116 is lower then 1.25.

Key value for chemical safety assessment

Koc at 20 °C:

1.25