cis-4-tert-butylcyclohexyl acetate

Adsorption / desorption

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

adsorption / desorption: screening

Type of information:

experimental study

Adequacy of study:

key study

Study period:

From 29 August 2012 to 02 October 2012

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Remarks:

This study was performed according to OECD Guideline 121 and EU Method C.19 with GLP statement. This study is well documented and all validity criteria were fulfilled. No deviations were observed.

Justification for type of information:

TBD
Validation applies with restrictions, as the test substance is not the registered substance. However, read-across is justified as data relates to mixture of isomers of the registered substance (monoconstituent). Indeed, the test substance is a mixture of two diastereomers, approximately 1:2 (cis:trans) which cis-diastereomer corresponds to the registered substance.

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

Qualifier:

according to guideline

Guideline:

EU Method C.19 (Estimation of the Adsorption Coefficient (KOC) on Soil and Sewage Sludge Using High Performance Liquid Chromatography (HPLC))

Deviations:

no

Principles of method if other than guideline:

Not applicable

GLP compliance:

yes (incl. QA statement)

Remarks:

UK GLP Compliance Programme (inspected on 10 July 2012 / signed on 30 Nov. 2012)

Type of method:

HPLC estimation method

Media:

soil/sewage sludge

Radiolabelling:

no

Test temperature:

30°C (Column temperature)

Details on study design: HPLC method:

EQUIPMENT
- Apparatus: HPLC System
- Type: Agilent Technologies 1100, incorporating autosampler and workstation.
- Type, material and dimension of analytical (guard) column: Column = Xselect HSS cyano 5 µm (150 x 4.6 mm id)
- Detection system: UV detector wavelength (210 nm)

MOBILE PHASES
- Type: Methanol:water (55:45 v/v)
- pH: 5.4
- Solutes for dissolving test and reference substances: The test item and reference standards were prepared in methanol. The dead time solution was diluted in methanol:water (55:45 v/v).

DETERMINATION OF DEAD TIME
- Method: by inert substances which are not retained by the column (formamide, purity 99.94%)

REFERENCE SUBSTANCES
- Identity: Phenol, Atrazine, Isoproturon, Triadimenol, Linuron, Naphthalene, Endosulfan-diol, Fenthion, alpha-Endosulfan, Phenanthrene, Diclofop-methyl, DDT.

DETERMINATION OF RETENTION TIMES
- Quantity introduced in the column: Injection volume 10 µL; Flow rate 1.0 mL/min.

REPETITIONS
- Number of determinations: The sample, dead time and reference standard solutions were injected in duplicate.

EVALUATION
- Calculation of capacity factors k' = (tr - t0) / t0, which tr = retention time (min) and t0 = dead time (min).
- Determination of the log Koc value = (log k' - A) / B, which A = intercept of the calibration curve and B = slope of the calibration curve.

Details on sampling:

Not applicable

Details on matrix:

Not applicable

Details on test conditions:

Not applicable

Computational methods:

Not applicable

Key result

Type:

log Koc

Value:

> 3.51 - < 3.66 dimensionless

Temp.:

30 °C

Remarks on result:

other: The definitive test was a range based on two values as the test item contained 2 isomeric forms.

Key result

Type:

Koc

Value:

> 3 243 - < 4 603 L/kg

Temp.:

30 °C

Remarks on result:

other: The definitive test was a range based on two values as the test item contained 2 isomeric forms.

Details on results (HPLC method):

- Retention times of reference substances used for calibration: See table 5.4.1/1 in "Any other information on results incl. tables".
- Details of fitted regression line (log k' vs. log Koc): A = -0.489; B = 0.299; r²=0.979.
- Graph of regression line attached: Yes. See in "Illustration"
- Average retention data for test substance: See table 5.4.1/2 in "Any other information on results incl. tables".

The definitive test was a range based on two values as the test item contained 2 isomeric forms. The two peaks at approximately 6 and 8 minutes were considered to be impurities (see typical chromatography in "Attached background material").

Adsorption and desorption constants:

Not applicable

Recovery of test material:

Not applicable

Concentration of test substance at end of adsorption equilibration period:

Not applicable

Concentration of test substance at end of desorption equilibration period:

Not applicable

Transformation products:

not measured

Details on results (Batch equilibrium method):

Not applicable

Statistics:

Not applicable

Table 5.4.1/1: The retention times of the dead time and the reference times, capacity factors and log Koc values for the reference standards

Standard	Retenion time (mins)		Mean retention time (mins)	Capacity factor (k’)	Log k’	Log Koc
	Injection 1	Injection 2
Formamide*	1.895	1.890	1.893	-	-	-
Phenol**	2.541	2.541	2.541	0.343	-0.465	1.32
Atrazine	3.756	3.756	3.756	0.985	-6.71 x 10^-3	1.81
Isoproturon	4.067	4.067	4.067	1.149	6.03 x 10^-2	1.86
Triadimenol	5.646	5.651	5.649	1.985	0.298	2.40
Linuron	5.816	5.821	5.819	2.075	0.317	2.59
Naphthalene	4.951	4.951	4.951	1.616	0.208	2.75
Endosulfan-diol	7.483	7.483	7.483	2.954	0.470	3.02
Fenthion	8.97	8.965	8.968	3.738	0.573	3.31
Apha-endosulfan	13.275	13.275	13.275	6.015	0.779	4.09
Diclofop-methyl	14.179	14.169	14.174	6.490	0.812	4.20
Phenanthrene	9.752	9.752	9.752	4.153	0.618	4.09
DDT	29.956	29.956	29.956	14.829	1.171	5.63

* Dead time

** Phenol was not used in the calibration curve, and hence to calculate the sample result, as it was considered to have poor correlation with respect to the other reference standards.

Table 5.4.1/2: The retention times, capacity factor and log Koc values determined for the sample

Peak	Injection number	Retention time (mins)	Capacity factor (k’)	Log k’	Log Koc	Mean log Koc	Adsorption coefficient
1	1	8.761	3.629	0.560	3.511	3.511	3243
	2	8.761	3.629	0.560	3.511
2	1	9.519	4.030	0.605	3.663	3.663	4603
	2	9.524	4.032	0.606	3.664

Percentage area normalization:

Peak 1 = 26.3 % (corresponding to cis isomer)

Peak 2 = 70.0 % (corresponding to trans isomer)

Total of 96.3%

Validity criteria fulfilled:

yes

Conclusions:

The adsorption coefficient (Koc) of the test substance has been determined to be in the range of 3 243 (log Koc = 3.51) to 4 603 (log Koc = 3.66), corresponding to cis and trans isomers respectively. The result indicates that the test item is environmentally slightly mobile in soils (according to P.J. McCall et al., 1980).

Executive summary:

This study was performed according to OECD Guideline 121 and EU Method C.19 with GLP statement, to assess the adsorption coefficient of the test substance. The test utilized a high performance liquid chromatograph. A commercially available cyanopropyl reverse phase HPLC column containing lipophilic and polar moieties was used.

As the slope of the calibration curve for the reference standards showed good first order correlation and as the retention times between duplicate injections for each solution was consistent, the HPLC method was considered valid for the determination of adsorption coefficient. Based on the chromatographic data, the test item was considered to be stable during the test procedure.

All validity criteria were fulfilled.

The adsorption coefficient (Koc) of the test substance has been determined to be in the range of 3 243 (log Koc = 3.51) to 4 603 (log Koc = 3.66), corresponding to cis and trans isomers. The two peaks at approximately 6 and 8 minutes were considered to be impurities.

The result indicates that the test item is environmentally slightly mobile in soils (according to P.J. McCall et al., 1980).

Reference 2

Endpoint:

adsorption / desorption: screening

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Justification for type of information:

REPORTING FORMAT FOR THE ANALOGUE APPROACH
[further information is included as attachment to Iuclid section 13]

1. HYPOTHESIS FOR THE ANALOGUE APPROACH
This read-across approach is based on the hypothesis that the source and target substances have similar physico-chemical, (eco)toxicological and environmental fate properties because of their structural similarity.

2. SOURCE AND TARGET CHEMICAL(S) (INCLUDING INFORMATION ON PURITY AND IMPURITIES)
The target and source substances are structurally related, in that both are 4-tert-butylcyclohexyl acetate. They differ by the spatial position of the acetate and tert-butyl substituents to the cycle, and by the composition ratio. The source substance is a reaction-mass of both cis and trans isomers whereas the target substance is mainly the cis isomer, the trans- form being considered as an impurity up to 20%. This impurity being part of the source substance, it is concluded that it will not affect the validity of the read-across.

3. ANALOGUE APPROACH JUSTIFICATION
Adsorption coefficient was not available for the individual isomers, but a HPLC study was conducted in 2012 on the source substance, which contains both the cis and trans forms. Two peaks were detected and therefore two adsorption coefficients were determined, corresponding to both cis and trans isomers. Hence, it’s considered suitable and scientifically justified to read-across the data between the two substances to fill the adsorption endpoint in the present dossier. The adsorption coefficient determined for the cis-isomer was considered for the target substance.

4. DATA MATRIX
See attached document in Iuclid section 13.

Reason / purpose for cross-reference:

read-across source

Reason / purpose for cross-reference:

read-across: supporting information

Remarks:

Read-across justification document

Key result

Type:

log Koc

Value:

3.51 dimensionless

Temp.:

30 °C

Remarks on result:

other: Result based on the cis-isomer

Key result

Type:

Koc

Value:

3 243 L/kg

Temp.:

30 °C

Remarks on result:

other: Result based on the cis-isomer

Table 5.4.1/1: The retention times, capacity factor and log Koc values determined for the sample

Peak	Injection number	Retention time (mins)	Capacity factor (k’)	Log k’	Log Koc	Mean log Koc	Adsorption coefficient
1	1	8.761	3.629	0.560	3.511	3.511	3243
	2	8.761	3.629	0.560	3.511
2	1	9.519	4.030	0.605	3.663	3.663	4603
	2	9.524	4.032	0.606	3.664

Percentage area normalization:

Peak 1 = 26.3 % (corresponding to cis isomer)

Peak 2 = 70.0 % (corresponding to trans isomer)

Total of 96.3%

Validity criteria fulfilled:

yes

Conclusions:

The adsorption coefficient (Koc) of the source substance has been determined to be in the range of 3 243 (log Koc = 3.51) to 4 603 (log Koc = 3.66), corresponding to cis and trans isomers respectively. As cis-isomer corresponds to the target substance (monoconstituent), the key Koc value at 3 243 (log Koc = 3.51) is considered for the registered substance. The result indicates that the substance is environmentally slightly mobile in soils (according to P.J. McCall et al., 1980).

Executive summary:

This study was performed according to OECD Guideline 121 and EU Method C.19 with GLP statement, to assess the adsorption coefficient of the test substance. The test utilized a high performance liquid chromatograph. A commercially available cyanopropyl reverse phase HPLC column containing lipophilic and polar moieties was used.

As the slope of the calibration curve for the reference standards showed good first order correlation and as the retention times between duplicate injections for each solution was consistent, the HPLC method was considered valid for the determination of adsorption coefficient. Based on the chromatographic data, the test item was considered to be stable during the test procedure.

All validity criteria were fulfilled.

The adsorption coefficient (Koc) of the test (source) substance has been determined to be in the range of 3 243 (log Koc = 3.51) to 4 603 (log Koc = 3.66), corresponding to cis and trans isomers, respectively. The two peaks at approximately 6 and 8 minutes were considered to be impurities. As cis-isomer corresponds to the target substance (monoconstituent), the key Koc value at 3 243 (log Koc = 3.51) is considered for the registered substance. The result indicates that the substance is environmentally slightly mobile in soils (according to P.J. McCall et al., 1980).

Description of key information

Read-Across, OECD Guideline 121, EU Method C.19, GLP, key study, validity 1:

Koc = 3 243 (for cis isomer); log Koc = 3.51 (for cis isomer)

Slightly mobile in soils (according to P.J. McCall et al., 1980).

Key value for chemical safety assessment

Koc at 20 °C:

3 243

Additional information

No adsorption study is available on the registered (target) substance, therefore good quality data for a related source substance have been read-across for this endpoint. The target and the source substances

The target and source substances are structurally related, in that both are 4-tert-butylcyclohexyl acetate. They differ by the spatial position of the acetate and tert-butyl substituents to the cycle, and by the composition ratio. The source substance is a reaction-mass of both cis and trans isomers whereas the target substance is mainly the cis isomer, the trans- form being considered as an impurity up to 20%. This impurity being part of the source substance, it is concluded that it will not affect the validity of the read-across.

Adsorption coefficient was not available for the individual isomers, but a HPLC study was conducted in 2012 on the source substance, which contains both the cis and trans forms. Two peaks were detected and therefore two adsorption coefficients were determined, corresponding to both cis and trans isomers. Hence, it’s considered suitable and scientifically justified to read-across the data between the two substances to fill the adsorption endpoint in the present dossier. The adsorption coefficient determined for the cis-isomer was considered for the target substance.

The experimental study was performed on the source substance,according to OECD Guideline 121 and EU Method C.19 with GLP statement, to estimate the adsorption coefficient Koc in soil and sewage sludge of the substance using HPLC method. Under the conditions of the test, two adsorption coefficients (Koc) of the test substance were found: one at 3 243 (log Koc = 3.51) and the second at 4 603 (log Koc = 3.66), corresponding to cis and trans isomers respectively. As the registered substance is a monoconstituent, corresponding to the cis isomer, the adsorption coefficient (Koc) can be determined to be 3 243 (log Koc = 3.51). The result indicates that the registered substance is environmentally slightly mobile in soils(according to P.J. McCall et al., 1980).