[No public or meaningful name is available]

Adsorption / desorption

Administrative data

Endpoint:

adsorption / desorption: screening

Type of information:

experimental study

Adequacy of study:

key study

Study period:

10 November 2020 - 08 December 2020

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Remarks:

Study conducted according OECD guideline 121, under GLP without deviation and with certificate of analysis included.

Cross-reference

Cross-reference 1

Reason / purpose for cross-reference:

reference to same study

Cross-reference 2

Reason / purpose for cross-reference:

reference to other study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2020

Report date:

2020

Materials and methods

Test guideline

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))

GLP compliance:

yes (incl. QA statement)

Remarks:

2018-11-15

Type of method:

HPLC estimation method

Media:

soil/sewage sludge

Test material

Test material information

Constituent 1

Reference substance name:

Reaction mass of (±)-(4RS,4aRS,8RS,8aRS)-4-ETHYL-8,8a-DIMETHYLOCTAHYDRO-1(2H)-NAPHTHALENONE and (±)-(4RS,4aSR,8SR,8aSR)-4-ETHYL-8,8a-DIMETHYLOCTAHYDRO-1(2H)-NAPHTHALENONE and (±)-(4RS,4aSR,8RS,8aSR)-4-ETHYL-8,8a-DIMETHYLOCTAHYDRO-1(2H)-NAPHTHALENONE

Molecular formula:

C14H24O

IUPAC Name:

Reaction mass of (±)-(4RS,4aRS,8RS,8aRS)-4-ETHYL-8,8a-DIMETHYLOCTAHYDRO-1(2H)-NAPHTHALENONE and (±)-(4RS,4aSR,8SR,8aSR)-4-ETHYL-8,8a-DIMETHYLOCTAHYDRO-1(2H)-NAPHTHALENONE and (±)-(4RS,4aSR,8RS,8aSR)-4-ETHYL-8,8a-DIMETHYLOCTAHYDRO-1(2H)-NAPHTHALENONE

Test material form:

liquid

Details on test material:

Physical state: liquid
Storage condition of test material: Dry area, protected from light, in a refrigerator (2-8ºC)
Other: Colourless liquid

Study design

HPLC method

Details on study design: HPLC method:

Reagents:

Acetone: Pestipur – for pesticides analysis, CARLO ERBA
Methanol: Baker analysed LC-MS Reagent, J.T. BAKER
Ultrapure water: deionised in the laboratory (resistivity 18.2 MΩ.cm, filtered at 0.2 μm)
Sodium Nitrate: AnalaR NORMAPUR ACS, Reag. Ph. Eur., VWR Chemicals

Analytical instruments:

HPLC-DAD: Waters 996
Column: Roc Cyano (4.6 x 150 mm, 5μm), RESTEK
Method identification: logKoc_55_45set
Apparatus: Thermometer Precision scale

Analytical parameters:

Mobile phase: Methanol: 55%
                       Ultrapure water: 45%
Injection volume: 50 μL
Column flow: 1 mL/min
Column temperature: 30 ± 1 °C
Detection wavelength: 200 nm
Duration: 15 minutes

Preparation of the test item solution:

A stock solution of the test item was be prepared at a concentration of 9.72 g/L in acetone. A diluted solution at 97.2 mg/L was prepared in the HPLC mobile phase. Sodium nitrate at 1 mg/L was added to this solution. These concentrations were adjusted depending on the response intensity of the compound on the system.

Preparation of the reference items solution:

Concerning the reference substance solutions prepared from pure analytical standard, a stock solution of each reference substance was prepared at a concentration of approximately 1 g/L in acetone. These solutions were kept at 1 - 5 °C for 6 months.
A diluted reference solution containing all the reference substances was prepared in the HPLC mobile phase. The concentrations were adjusted depending on the response intensity of each compound on the system, according to the following table. Sodium nitrate at 1 mg/L was added to this mix.

Reference item - Concentration in the mix (mg/L)
phenol: 5.35 mg/L
isoproturon: 2.5 mg/L
triazoxide: 10.5 mg/L
1,2,3-trichlorobenzene: 2.5 mg/L
pyrazophos: 10 mg/L
phenanthrene: 5 mg/L
DDT: 10 mg/L

Results and discussion

Adsorption coefficient

Type:

log Koc

Value:

> 2.79 - < 3.37 dimensionless

Temp.:

30.1 °C

Any other information on results incl. tables

RESULTS AND DISCUSSION

Retention times and capacity factors:

The retention times of the reference items are presented in the table below:

Compound	tR 1 (min)	tR 2 (min)	ΔtR (min)	tR mean (min)	ΔtR / tR mean	Equilibrium ?
phenol	2.49	2.48	0.01	2.49	0.40%	YES
isoproturon	2.97	2.96	0.01	2.97	0.34%	YES
triazoxide	3.47	3.45	0.02	3.46	0.58%	YES
1,2,3-trichlorobenzene	4.08	4.05	0.03	4.07	0.74%	YES
pyrazophos	5.09	5.05	0.04	5.07	0.79%	YES
phenanthrene	5.38	5.35	0.03	5.37	0.56%	YES
DDT	10.29	10.19	0.10	10.24	0.98%	YES

with t_R: retention time
Δt_R: absolute value of the retention times difference
The dead time (t₀) was to 1.06 min for the first injection of the reference items mix and to 1.05 min for the second injection.
The equilibrium state of the system was declared since the difference of the reference items retention times (Δt_R / t_R mean) did not exceed 5% between two analyses.

log k over log K_OC:

The following table presents for each reference item their log K_OC, the calculated retention factor for the two injections (k₁ and k₂), the mean of k₁ and k₂ (k mean), and the log (k mean):

Compound	log Koc	k1	k2	k mean	log (k mean)
phenol	1.32	1.35	1.36	1.36	0.13
isoproturon	1.86	1.80	1.82	1.81	0.26
triazoxide	2.44	2.27	2.29	2.28	0.36
1,2,3-trichlorobenzene	3.16	2.85	2.86	2.86	0.46
pyrazophos	3.65	3.80	3.81	3.81	0.58
phenanthrene	4.09	4.08	4.10	4.09	0.61
DDT	5.63	8.71	8.70	8.71	0.94

The logarithms of the adsorption coefficients, log K_OC, are plotted as a function of the mean capacity factors, log k. The linear regression obtained with the reference items is presented in the following graph with the representation of the confidence interval (in orange) calculated with a 98% confidence level: (see graphic)

The determination coefficient R₂ observed is 0.9936 and the correlation coefficient R is 0.9968. According to the guideline, a typical correlation for the relationship between log K_OC and log k for a set of test substances is around 0.95. Therefore, the obtained coefficients are satisfactory.
The equation of the line issued from this linear regression was used for the test item log K_OC calculation.

Test item:

Retention times and capacity factors:

A typical chromatogram of the test item is constituted of a set of peaks. The retention times obtained are presented below:

	Injection 1 tR (min)	Injection 2 tR (min)	tR mean (min)	Relative standard deviation
Dead time t0	1.11	1.11	1.11	0.0%
Test item, beginning of elution	3.98	3.95	3.97	0.5%
Test item, end of elution	4.72	4.76	4.74	0.6%

Calculation of k, log k and log K_OC:

The calculated values for the two peaks of the test item are presented in the following table. log K_OC is calculated using the regression equation obtained from the reference items:
log K_OC = ( log k + 0.0970 ) / 0.1815

	Test item, beginning of elution			Test item, end of elution
Measurement No.	k	log k	log KOC	log KOC	log k	log KOC
1	2.59	0.41	2.79	3.25	0.51	3.34
2	2.56	0.41	2.79	3.29	0.52	3.40
	log KOC mean		2.79	log KOC mean		3.37
	Standard deviation		0.000	Standard deviation		0.042

The pH value measured in the water used for the mobile phase was 5.
The temperature of the oven containing the HPLC column was to 30.1°C.

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Conclusions:

Using the HPLC method, the following adsorption coefficients were determined for the test item:
2.79 < log KOC < 3.37.
These values are the mean of two independent measurements.

Executive summary:

A study was performed to estimate the Adsorption Coefficient (log KOC) on Soil and Sewage Sludge of the test item using HPLC (High Performance Liquid Chromatography). The method followed was designed to be compliant with the OECD Guideline for Testing of Chemicals No. 1211.

This study was performed using the HPLC method. Seven reference items with different retention times were used to produce the calibration curve. They were chosen in relation with the expected retention time of the test item. For each reference item, two determinations were performed. The capacity factor k was calculated from the retention time of sodium nitrate (dead time) and the retention time of the respective reference item. A calibration function (log k versus log KOC, linear fit) was determined based on literature values of KOC for the reference items.

The following adsorption coefficients were determined for the test item:
2.79 < log KOC < 3.37.
These values are the mean of two independent measurements.