2,6-bis(4-ethylphenyl)perhydro-1,3,5,7-tetraoxanaphth-4-ylethane-1,2-diol

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:

Experimental starting date: 04 March 2020; Experimental completion date: 13 March 2020

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

Test temperature:

30°C

Details on study design: HPLC method:

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

Performance of the Test:
Preparation of dead time solution: The dead time was determined by measuring the retention time of a solution of formamide (purity 99.6%) at 708 mg/L in methanol:water (55:45 v/v).

Preparation of reference standard solutions:
Solutions of reference standards (see below) were prepared in methanol.
Standard Purity (%) Concentration (mg/L)
Acetanilide 99+ 108
Phenol 99 106
Atrazine 99 107
Isoproturon >98.0 109
Triadimenol 97.8 102
Linuron 99.7 106
Naphthalene 99 113
Endosulfan-diol 99.9 109
Fenthion 98.6 109
Endosulfan 99.8 116
Diclofop-methyl 99.8 146
Phenanthrene ≥99.5 100
DDT 98.7 123

Preparation of sample solution:
Test item (0.0997g) was diluted to 100 mL with dimethyl sulfoxide and diluted by a factor of 2 with methanol to give a concentration of 499 mg/L.

Determination of retention time:
The sample, dead time and reference standard solutions were injected in duplicate using the following HPLC parameters:
HPLC System: Agilent Technologies 1100, incorporating workstation and autosampler
Detector type: variable wavelength (VW)
Column: XSelect HSS Cyano 5µ (150 x 4.6 mm id)
Column temperature: 30 °C
Mobile phase: methanol:water (55:45 v/v)
pH of mobile phase: 7.2
Flow-rate: 1.0 mL/min
Injection volume: 10 µL
VW detector wavelength: 210 nm

Evaluation of Data:
Capacity factor:
The capacity factor for each reference standard was calculated using the following equation:
k' = tr - t0 / t0
where:
k' = capacity factor
tr = retention time (min)
t0 = dead time (min)

Construction of the calibration curve:
A correlation of log10 k' versus log10 Koc of the reference standards was plotted using linear regression. The capacity factors (k') for the reference standards were calculated using the previous equation. Log10 Koc values are those quoted in Method 121 of the OECD Guidelines for Testing of Chemicals, 22 January 2001.

Adsorption coefficient:
The adsorption coefficient was then calculated using the following equation with reference to the calibration curve.
lgo10Koc = log10 k' - A / B
where:
Koc = adsorption coefficient
k' = capacity factor
A = intercept of the calibration curve
B = slope of the calibration curve

Type:

Koc

Value:

1 890 dimensionless

pH:

7.2

Temp.:

30 °C

Type:

log Koc

Value:

3.28 dimensionless

pH:

7.2

Temp.:

30 °C

Calibration:

The retention times of the dead time and the retention times, capacity factors and log₁₀K_ocvalues for the reference standards are shown in the following table:

Standard	Retention Time (min)		Mean Retention Time (min)	Capacity Factor (k')	Log10k'	Log10Koc
	Injection 1	Injection 2
Formamide (dead time)	1.969	1.969	1.969	-	-	--
Acetanilide	2.695	2.695	2.695	0.369	-0.433	1.25
Phenol	2.574	2.576	2.575	0.308	-0.511	1.32
Atrazine	3.712	3.714	3.713	0.886	-5.26 x 10^-2	1.81
Isoproturon	3.960	3.957	3.959	1.011	4.66 x 10^-3	1.86
Triadimenol	5.314	5.318	5.316	1.700	0.231	2.40
Linuron	5.444	5.449	5.446	1.766	0.247	2.59
Naphthalene	4.720	4.725	4.722	1.399	0.146	2.75
Endosulfan-diol	6.744	6.752	6.748	2.428	0.385	3.02
Fenthion	8.035	8.049	8.042	3.085	0.489	3.31
a-Endosulfan	11.406	11.411	11.408	4.795	0.681	4.09
Diclofop-methyl	12.336	12.359	12.348	5.272	0.722	4.20
Phenanthrene	8.809	8.819	8.814	3.477	0.541	4.09
DDT	24.152	24.267	24.210	11.297	1.05	5.63

Adsorption Coefficient

The retention time, capacity factor and log₁₀K_ocvalues determined for the sample are shown in the following table:

Table 3

Injection	Retention Time (min)	Capacity Factor (k')	Log10k'	Log10Koc
1	6.685	2.40	0.379	3.28
2	6.689	2.40	0.380	3.28

Mean log₁₀K_oc:                    3.28
Adsorption coefficient:          1.89 x 10³

Validity criteria fulfilled:

yes

Conclusions:

The adsorption coefficient of the test item has been determined to be 1890, log10 Koc 3.28.

Executive summary:

The adsorption coefficient of EDBS has been determined to be 1.89 x 10³, log₁₀K_oc 3.28, using the HPLC screening method, designed to be compatible with Method C.19 Adsorption Coefficient of Commission Regulation (EC) No 440/2008 of 30 May 2008 and Method 121 of the OECD Guidelines for Testing of Chemicals, 22 January 2001.

Description of key information

The adsorption coefficient of EDBS has been determined to be 1.89 x 10³, log₁₀K_oc 3.28, using the HPLC screening method.

Key value for chemical safety assessment

Koc at 20 °C:

1 890