hydrogenation products of (esterification products of 2-ethylhexan-1-ol with (Estolide formation products of oleic acid and Fatty acids, C8-18 and C18-unsatd. (branched or linear)).

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: 10 March 2015, Experimental Completion Date: 30 March 2015

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: 1= Reliable without restriction o GLP guideline study

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: HPLC method

Details on study design: HPLC method:

Test System
The determination was carried out using the HPLC screening method, designed to be compatible with Method C19 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.
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 sample solution
Test item (0.1514 g) was diluted to 100 mL with acetonitrile to give a concentration of 1.514 g/L.
-Preparation of dead time solution
The dead time was determined by measuring the retention time of formamide (purity 99.94%, 644 mg/L solution in 55:45 acetonitrile: purified water).
-Preparation of reference standard solutions
Solutions of reference standards (see the table) were prepared in methanol.

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 1200 series, incorporating autosampler and workstation
- Polymer Laboratories Evaporative Light Scattering Detector 1000 (ELSD)
Column :
- Waters XSelect HSS Cyano 5mm (150 x 4.6 mm id)
Column temperature :
- 40ºC
Mobile phase :
- 55:45 v/v Acetonitrile: purified water 100% Acetonitrile post 15 minutes (after DDT peak elution) pH of mobile phase : 8.18
Flow-rate :
- 1.0 mL/min
Injection volume :
- 10 μl (samples)
- 100 mL (standards)
UV detector wavelength (standards) :
- dead time and reference standards: 210 nm
ELS detector (samples) :
- Evap temperature : 80 °C
- Nebulizer temperature: 40 °C
- Gas flow: 1.0 mL /min

Calculation
Construction of calibration curve
A calibration curve was constructed from the retention time data of the dead time and reference standard solutions. The capacity factors k' for the reference standards were calculated using the equation below.

Adsorption coefficient of sample
The capacity factor was calculated using the following equation:
k' = ( tr – t₀ ) / t₀
where:
k' = capacity factor
tr = retention time (min)
t₀ = dead time (min)

and the log₁₀Koc value determined using the following equation with reference to the calibration curve.
Log₁₀ Koc = ( log₁₀ k' – A ) / B
where:
Koc = adsorption coefficient
k' = capacity factor
A = intercept of the calibration curve
B = slope of the calibration curve

A correlation of log k' versus log Koc of the calibration standards was plotted using linear regression.

The mobility classification of the test item was obtained by comparing the calculated Koc value to the mobility classes according to P.J. McCall, R.L. Swann, D.A. Laskowski, S.M. Unger, S.A. Vrona and H.J. Dishburger “Estimation of Chemical Mobility in Soil from Liquid Chromatography Retention Times”; Bull. Environm. Contam. Toxicol. 24, 190-195 (1980).

Range of Koc // Mobility Class
0-50 = Very high
50-150 = High
150-500 = Medium
500-2000 = Low
2000-5000 = Slightly
>5000 = Immobile

Key result

Type:

log Koc

Value:

> 5.63 dimensionless

Type:

Koc

Value:

> 427 000 dimensionless

Details on results (HPLC method):

Adsorption coefficient of sample
The retention times, capacity factor and log10 Koc value determined for the sample are shown in the table below.
Overall log10 Koc: >5.63
Adsorption coefficient: >4.27 x 10^5

Discussion
As the test item had a high affinity for the stationary phase of the column, the mobile phase was adjusted to 100% acetonitrile shortly after the retention time of DDT to elute the sample. All peaks for the test item eluted after the adjustment to 100% acetonitrile, therefore the test item adsorption coefficient has been quoted as greater than DDT.
The test item has a very low solubility in methanol and water, therefore acetonitrile was chosen as a suitable organic solvent for the mobile phase in order to maintain solubility of the test item.
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 there was no shift in retention time.

Conclusion
The adsorption coefficient (Koc) of the test item has been determined to be greater than 5.63, greater than log₁₀Koc 4.27 x 10^5. These values indicate that the test item will be immobile in the environment.

Adsorption coefficient of sample

Peak	Injection	Retention Time (mins)	Capacity Factor (k')	Log10K'	Log10Koc	Mean Log10Koc	Adsorption Coefficient
TI	1	16.517	8.38	0.923	>5.63	>5.63	>4.27 x 10^5
TI	2	16.517	8.38	0.923	>5.63
TI2	1	16.683	8.47	0.928	>5.63	>5.63	>4.27 x 10^5
TI2	2	16.683	8.47	0.928	>5.63

Validity criteria fulfilled:

yes

Conclusions:

The adsorption coefficient (Koc) of the test item has been determined to be greater than 4.27 x 10^5, greater than log₁₀Koc 5.63. These values indicate that the test item will be immobile in the environment.

Description of key information

The adsorption coefficient (Koc) of the test item has been determined to be greater than 4.27 x 10^5, greater than log₁₀Koc 5.63 . These values indicate that the test item will be immobile in the environment.

Key value for chemical safety assessment

Koc at 20 °C:

427 000

Additional information

The adsorption coefficient (Koc) of the test item has been determined to be greater than 4.27 x 10^5, greater than log₁₀Koc 5.63. These values indicate that the test item will be immobile in the environment.

[LogKoc: 5.63]