1,2,3,4,4a,7,8,8a-octahydro-2,4a,5,8a-tetramethyl-1-naphthyl formate

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:

The study was conducted between 09 June 2014 and 06 October 2014.

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

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

GLP compliance:

yes (incl. QA statement)

Type of method:

HPLC estimation method

Media:

other: No data

Specific details on test material used for the study:

Batch: SC00010054
Purity: 96.5% (sum of four peaks)
Appearance / Physical Description: Clear colorless liquid

Radiolabelling:

no

Test temperature:

The determination was performed at 30°C (column temperature), however the values can be considered to represent the values at an unspecified, probably ambient temperature since no mention is made in the guidelines of the temperature at which the tabulated reference substances log Koc values were determined. Adsorption coefficients of the test and reference substances are assumed to vary with temperature in the same way.

Details on study design: HPLC method:

The test system utilized a high performance liquid chromatograph. A commercially available cyanopropyl reverse phase HPLC column containing lipophilic and polar moieties was used.

Preparation of sample solution
Test item (0.0485 g) was diluted to 100 ml with methanol to give a concentration of 485 mg/L.

Preparation of dead time solution
The dead time was determined by measuring the retention time of formamide (purity quoted by the supplier 99.94 %, 698 mg/L solution in 55:45 v/v methanol: purified water).

HPLC System: Agilent Technologies, incorporating autosampler and workstation
Column: Waters XSelect HSS Cyano 5 µm (150 x 4.6 mm id)
Column temperature: 30 ºC
Mobile phase: 5:45 v/v methanol: purified water
pH of mobile phase: 6.02
Flow-rate: 1.0 mL/min
Injection volume: 10 µL
UV detector wavelength : 210 nm

Type:

log Koc

Value:

3.38

Temp.:

30 °C

Remarks on result:

other: 1.94% area normalisation

Type:

log Koc

Value:

4.02

Temp.:

30 °C

Remarks on result:

other: 78.3% area normalisation

Type:

log Koc

Value:

4.13

Temp.:

30 °C

Remarks on result:

other: 1.76% area normalisation

Type:

log Koc

Value:

4.31

Temp.:

30 °C

Remarks on result:

other: 12.4% area normalisation

Details on results (HPLC method):

The chromatograms of Oxyoctaline Formate show four main peaks at retention times of 7.1 minutes (1.94% area normalization); 10.5 minutes (78.3% ); 11.3 minutes (1.76%) and 12.7 minutes (12.4%) corresponding to Log Koc values of 3.38, 4.02, 4.13 and 4.32 and adsorption coefficients Koc values of 2410, 10400, 13500 and 20300.

A number of additional peaks present at < 1% were also observed (see attached fiull study report and the section "any other information on results incl.tables)")

The determination was performed at 30°C (column temperature), however the values can be considered to represent the values at an unspecified, probably ambient temperature since no mention is made in the guidelines of the temperature at which the tabulated reference substances log Koc values were determined. Adsorption coefficients of the test and reference substances are assumed to vary with temperature in the same way.

Calibration

The retention times of the dead time and the retention times, capacity factors (k') and log₁₀K_ocvalues for the reference standards are shown in the two following tables:

Dead Time	Retention Time (mins)		Mean Retention Time (mins)
	Injection 1	Injection 2
Formamide	1.878	1.880	1.879

Standard	Retention Time (mins)		Mean Retention Time (mins)	Capacity Factor (k')	Log10k'	Log10Koc
	Injection 1	Injection 2
Acetanilide	2.603	2.606	2.604	0.386	-4.13	1.25
Phenol	2.482	2.482	2.482	0.321	-0.494	1.32
Atrazine	3.617	3.615	3.616	0.924	-3.41 x 10^-2	1.81
Isoproturon	3.884	3.884	3.884	1.067	2.82 x 10^-2	1.86
Triadimenol	5.267	5.267	5.267	1.803	0.256	2.40
Linuron	5.415	5.420	5.417	1.883	0.275	2.59
Naphthalene	4.663	4.660	4.662	1.481	0.171	2.75
Endosulfan-diol	6.771	6.769	5.770	2.603	0.415	3.02
Fenthion	8.110	8.110	8.110	3.316	0.521	3.31
a-Endosulfan	11.647	11.652	11.650	5.200	0.716	4.09
Diclofop-methyl	12.489	12.496	12.493	5.649	0.752	4.20
Phenanthrene	8.823	8.819	8.821	3.695	0.568	4.09
DDT	25.046	25.049	25.047	12.331	1.09	5.63

Adsorption coefficient of sample

The retention times, capacity factor, % area normalization and log₁₀K_ocvalues determined for the sample are shown in the following tables:

Peak	Injection No.	Retention Time (mins)	Capacity Factor (k')	Log10k'	Log10Koc	Mean Log10Koc	Adsorption Coefficient (Koc)
1	1	5.109	1.72	0.235	2.77	2.77	584
	2	5.099	1.71	0.234	2.77
2	1	6.232	2.32	0.365	3.15	3.15	1.41 x 10^3
	2	6.220	2.31	0.364	3.15
3	1	7.089	2.77	0.443	3.38	3.38	2.41 x 10^3
	2	7.113	2.79	0.445	3.39
4	1	7.889	3.20	0.505	3.56	3.56	3.63 x 10^3
	2	7.872	3.19	0.504	3.56
5	1	8.314	3.42	0.535	3.65	3.65	4.44 x 10^3
	2	8.295	3.41	0.533	3.65
6	1	10.466	4.57	0.660	4.02	4.02	1.04 x 10^4
	2	10.468	4.57	0.660	4.02
7	1	11.245	4.98	0.698	3.13	4.13	1.35 x 10^4
	2	11.254	4.99	0.698	3.13
8	1	12.661	5.74	0.759	4.31	4.31	2.03 x 10^4
	2	12.656	5.74	0.759	4.31
9	1	13.372	6.12	0.787	4.39	4.39	2.44 x 10^4
	2	13.331	6.09	0.785	4.39
10	1	14.003	6.45	0.810	4.46	4.46	2.87 x 10^4
	2	14.008	6.468	0.810	4.46

11	1	15.342	7.17	0.855	4.59	4.59	3.90 x 10^4
	2	15.325	7.16	0.855	4.59
12	1	16.693	7.88	0.897	4.71	4.71	5.18 x 10^4
	2	16.691	7.88	0.897	4.71
13	1	23.057	11.3	1.05	5.17	5.17	1.49 x10^5
	2	23.173	11.3	1.05	5.18

Overall log₁₀K_oc: 2.77 to 5.17

Adsorption coefficient: 584 to 1.49 x 10⁵

Peak	Injection No.	Retention Time (mins)	Mean Log10Koc	Adsorption Coefficient (Koc)	% Area Normalization	Mean % Normalization
1	1	5.109	2.77	584	0.70	0.69
	2	5.099			0.67
2	1	6.232	3.15	1.41 x 10^3	0.30	0.29
	2	6.220			0.28
3	1	7.089	3.38	2.41 x 10^3	1.95	1.94
	2	7.113			1.92
4	1	7.889	3.56	3.63 x 10^3	0.55	0.51
	2	7.872			0.47
5	1	8.314	3.65	4.44 x 10^3	0.32	0.30
	2	8.295			0.27
6	1	10.466	4.02	1.04 x 10^4	78.45	78.3
	2	10.468			78.19
7	1	11.245	4.13	1.35 x 10^4	1.69	1.76
	2	11.254			1.82
8	1	12.661	4.31	2.03 x 10^4	12.32	12.4
	2	12.656			12.42
9	1	13.372	4.39	2.44 x 10^4	0.75	0.81
	2	13.331			0.87
10	1	14.003	4.46	2.87 x 10^4	0.48	0.53
	2	14.008			0.57

11	1	15.342	4.59	3.90 x 10^4	0.87	0.95
	2	15.325			1.02
12	1	16.693	4.71	5.18 x 10^4	0.98	0.97
	2	16.691			0.96
13	1	23.057	5.17	1.49 x 10^5	0.64	0.60
	2	23.173			0.55

Discussion

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. As the sample is a mixture of four isomers a range of adsorption coefficient (K_oc) can be quoted alongside the adsorption coefficient specific for the main peak found, determined by percentage are normalization.

 

The test item does not contain any modes of dissociation and as such testing was performed without pH adjustment to the mobile phase. Equally the reference substances used do not require the use of a buffered eluent.

Validity criteria fulfilled:

yes

Conclusions:

The chromatograms of Oxyoctaline Formate show four main peaks at retention times of 7.1 minutes (1.94% area normalization); 10.5 minutes (78.3% ); 11.3 minutes (1.76%) and 12.7 minutes (12.4%) corresponding to Log Koc values of 3.38, 4.02, 4.13 and 4.32 and adsorption coefficients Koc values of 2410, 10400, 13500 and 20300.

Description of key information

The adsorption coefficient of the test substance was assessed using the OECD 121 HPLC screening method. The determination was performed at 30°C (column temperature), however the values can be considered to represent the values at an unspecified, probably ambient temperature since no mention is made in the guidelines of the temperature at which the tabulated reference substances log Koc values were determined. Adsorption coefficients of the test and reference substances are assumed to vary with temperature in the same way.

The chromatograms of Oxyoctaline Formate show four main peaks at retention times of 7.1 minutes (1.94% area normalization); 10.5 minutes (78.3% ); 11.3 minutes (1.76%)  and 12.7 minutes (12.4%) corresponding to Log Koc values of 3.38, 4.02, 4.13 and 4.32 and adsorption coefficients of 2410, 10400, 13500 and 20300. Based on compositional information, the lowest log Koc value of 3.38 (Koc of 2410) can be attributed to the 2,4a,5,8a-tetramethyl-1,2,3,4,4a,7,8,8a-octahydronaphthalen-1-ol impurity present in the registration substance due to the more hydrophilic nature of the alcohol functional group promoting aqueous solubility and thus mobility in soils. The remaining three peaks are attributed to the mono-constituent component of Oxyoctaline formate and its isomeric impurities. Since a single value is required for the exposure assessment and calculation of PNECsediment & PNEC soil, the value corresponding to the largest peak has been selected as the key value.

Key value for chemical safety assessment

Koc at 20 °C:

10 400

Additional information

[LogKoc: 4.02]