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Reference
Endpoint:
adsorption / desorption: screening
Type of information:
experimental study
Adequacy of study:
key study
Study period:
30 November 2017 to 01 December 2017
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))
Version / remarks:
OECD Guideline for Testing of Chemicals No. 121., “Estimation of the Adsorption Coefficient (KOC) on Soil and on Sewage Sludge using High Performance Liquid Chromatography (HPLC)” (Original Guideline, adopted 22nd January 2001).
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))
Version / remarks:
Commission Regulation (EC) No 440/2008, Part C, C.19 “Estimation of the Adsorption Coefficient (KOC) on Soil and on Sewage Sludge Using High Performance Liquid Chromatography (HPLC)”, Official Journal of the European Union L 142 of 31 May 2008.
Deviations:
no
GLP compliance:
yes (incl. QA statement)
Type of method:
HPLC estimation method
Media:
soil
Specific details on test material used for the study:
No further details specified in the study report.
Radiolabelling:
no
Test temperature:
25°C
Details on study design: HPLC method:
APPARATUS
HPLC system: Knauer Azura HPLC-UV
Balance: Sartorius BP221S
Ultrasonic bath: ELMA Elmasonic S300
Water purification system: Millipore, Direct-Q 8 UV
Refrigerator: Zanussi

HPLC Conditions:
Column: LiChrospher 100 CN 250 × 4.6 mm, 5 µm
Mobil Phase: Acetonitrile : ultrapure water = 6 : 4
Flow: 1 mL/min
Detector (UV): 210 nm
Injection volume: 50 µL
Temperature: 25°C

PERFORMANCE OF THE TEST
Preparation of the Test Solutions:
Sodium nitrate was dissolved with the eluent in about 1 mg/mL concentration. Reference substances and test item were dissolved in acetonitrile. Concentration of reference stock solutions was about 1 mg/mL, the concentration of test item was about 0.5 µg/mL. The reference and the test item stock solutions were diluted with eluent resulting about 10 µg/mL solution, the sodium nitrate was diluted with eluent to about 100 µg/mL.

Determination of the retention times:
Three series of the above reference solutions and the test item solution were measured alternately, with two replicate injections.
For the determination of t0 (t0 = retention time of the unretarded component) sodium nitrate solution was injected.
The retention times were determined.
Key result
Type:
log Koc
Value:
5.4 dimensionless
Temp.:
25 °C
Details on results (HPLC method):
The three calibration series and three test item series were measured alternately. The adsorption coefficient Koc was determined based on a calibration curve using 6 reference items.
The capacity factors were calculated from the dead time and retention times of the reference substances. The log k data of the reference substances were plotted against their log Koc values.
log k = 0.0844 × log Koc – 0.0838 (R2= 0.9762)

Based on the chromatograms, one peak was detected from the test item at 6.29 min retention time. Based on the calibration, the log Koc of 6,6’-di-tert-butyl-2,2’-thiodi-p-cresol is to estimated 5.40 ± 0.005 (with 95% confidence interval).

Measured and calculated data of the reference substances

Chemical name

Log Koc

Retention time (min)

Logk

log Koc

Repeatability ∆logKoc, log unit

Accuracy log unit

From OECD 121

Calculated

Calculated

Sodium nitrate

-

1.88

For determination of dead time

1.87

1.88

1.88

1.87

1.87

Mean

1.88

CV%

0.3

Methyl benzoate

1.80

4.03

0.060

1.71

0.02

0.1

4.02

0.058

1.69

4.03

0.060

1.71

4.02

0.058

1.69

4.03

0.060

1.71

4.02

0.058

1.69

Mean

4.03

0.059

1.70

CV%

0.1

-

-

Isoproturon

1.86

3.98

0.050

1.59

0.05

0.27

3.99

0.052

1.61

3.98

0.050

1.59

3.98

0.050

1.59

3.97

0.048

1.56

3.98

0.050

1.59

Mean

3.98

0.050

1.59

CV%

0.1

-

-

Naphthalene

2.75

4.65

0.170

3.01

0.02

0.26

4.65

0.170

3.01

4.65

0.170

3.01

4.66

0.172

3.03

4.65

0.170

3.01

4.65

0.170

3.01

Mean

4.65

0.171

3.01

CV%

0.1

-

-

Fenthion

3.31

4.92

0.211

3.49

0.02

0.18

4.93

0.212

3.51

4.92

0.211

3.49

4.92

0.211

3.49

4.92

0.211

3.49

4.92

0.211

3.49

Mean

4.92

0.211

3.49

CV%

0.1

-

-

α-Endosulfan

4.09

5.41

0.275

4.26

0.03

0.15

5.40

0.274

4.24

5.40

0.274

4.24

5.39

0.273

4.23

5.41

0.275

4.26

5.39

0.273

4.23

Mean

5.40

0.274

4.24

RDS%

0.2

-

-

DDT

5.63

6.29

0.372

5.40

0.01

0.22

6.30

0.373

5.41

6.30

0.373

5.41

6.29

0.372

5.40

6.29

0.372

5.40

6.30

0.373

5.41

Mean

6.30

0.372

5.41

RSD%

0.1

-

-

 

Measured and calculated data of the test item

Test item

Log Kocfrom OECD 121

Retention time (min)

Logk

Log Koc

Repeatability ∆logKoclog unit

Calculated

Calculated

6,6’-di-tert-butyl-2,2’-thiodi-p-cresol

-

6.29

0.372

5.40

0.01

6.29

0.372

5.40

6.29

0.372

5.40

6.29

0.372

5.40

6.29

0.372

5.40

6.30

0.373

5.41

Mean

6.29

0.372

5.40

CV%

0.06

-

0.09

Conf. 95%

0.04

-

0.005

 

Validity criteria fulfilled:
yes
Conclusions:
Based on the chromatograms, one peak was detected from the test item at 6.29 min retention time. Based on the calibration, the log Koc of 6,6’-di-tert-butyl-2,2’-thiodi-p-cresol is to estimated 5.40 ± 0.005 (with 95% confidence interval).
Executive summary:

In the course of this study the adsorption coefficient (Koc) of 6,6’-di-tert-butyl-2,2’-thiodi-p-cresol was estimated using high performance liquid chromatography.

The estimated log Koc is found to be 5.40 ± 0.005 (with 95% confidence interval).

Description of key information

The estimated log Koc is found to be 5.40 ± 0.005 (with 95% confidence interval).

 

Key value for chemical safety assessment

Koc at 20 °C:
251 189

Additional information

In the course of this study the adsorption coefficient (Koc) of 6,6’-di-tert-butyl-2,2’-thiodi-p-cresol was estimated using high performance liquid chromatography.

The estimated log Koc is found to be 5.40 ± 0.005 (with 95% confidence interval).