Di-tert-dodecyl disulphide

Adsorption / desorption

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

adsorption / desorption: screening

Type of information:

experimental study

Adequacy of study:

supporting study

Study period:

09-12-2016 to 03-13-2017

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))

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 consisted of a mass spectrometer fitted with a time of fly mass analyzer and a UV spectrometer placed in series.

UPLC System: Waters UPLC System including binary solvent manager, sample manager, column heater and PDA detector
LCT Premier Mass Spectrometer
Column: Agilent technologies ZORBAX CN 5µm, dim: 2.1 x 150 mm
Column temperature: 30ºC
Mobile phase: Methanol : Water (55.0:45.0 v/v)
pH of mobile phase: 6.6 at 25°C, 6.7 at 30°C
Flow-rate: 0.8 mL/min
Injection volume: 5 µL
UV detector wavelength: 210 nm


DEFINITIVE TEST

The calibration curve was prepared from a reference item stock solution (Formamide, phenanthrene, DDT, acetanilide, methyl benzoate, triadimenol, naphtalene) diluted in methanol.

Key result

Type:

log Koc

Value:

> 5.63

pH:

6.7

Temp.:

30 °C

Details on results (HPLC method):

Using the capacity factor k’ and the partition coefficient log Koc of the reference items, the following calibration curve was obtained:

log Koc = 2.9442 log k’ + 2.2328 r2 = 0.983

The log Koc value for the test item was determined from this equation.
The log Koc value is > 5.63.

Test item results

Measure	Retention time (min)	Log k'	Log Koc	Average Log Koc
1	11.91	1.3233667	>5.63	>5.63
2	11.91	1.3233667	>5.63
3	11.90	1.32298457	>5.63

 

Validity criteria fulfilled:

yes

Conclusions:

The definitive test met the validity criteria of the test guideline detailed as follows: the value of log Koc derived from three repeated measurements made under identical conditions and using the same set of reference substances fell within a range of +/- 0.25 log units, the test is thus considered as valid.
The partition coefficient log Koc of the test item is >5.63.

Executive summary:

The definitive test met the validity criteria of the test guideline detailed as follows: the value of log Koc derived from three repeated measurements made under identical conditions and using the same set of reference substances fell within a range of +/- 0.25 log units, the test is thus considered as valid.

The partition coefficient log Koc of the test item is >5.63.

Reference 2

Endpoint:

adsorption / desorption: screening

Type of information:

experimental study

Adequacy of study:

key study

Study period:

June 15, 2010

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: see 'Remark'

Remarks:

Most of the validity criteria were met, but no reference data were available with results above the obtained value and the purity of the reference substances are not reported. Results for the test substance were extrapolated. GLP-compliant, guideline study. Reliable with restrictions.

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:

yes

Remarks:

A reference item with a Koc above the obtained value was not available so the Koc was extrapolated on the basis of the available reference items.

GLP compliance:

yes (incl. QA statement)

Type of method:

HPLC estimation method

Media:

other: cyanopropyl in the stationary phase

Specific details on test material used for the study:

Details on properties of test surrogate or analogue material (migrated information):
No data reported

Radiolabelling:

not specified

Test temperature:

25 +/- 1°C

Details on study design: HPLC method:

HPLC using DAD detector and cyanopropyl in the stationary phase and tetrahydrofuran/pure water (55%/45% v/v) in the mobile phase. 10 mg/l each of 7 structurally heterogeneous reference substances from the guidelines, with reported log Kocs, were used to calibrate the elution time. Retention times were recorded after the injection of both separate and mixed reference items. The mixed reference item was injected before and after each of the three injections of test item. Sodium nitrate was also injected three times in order to determine dead time.

Analytical monitoring:

no

Details on sampling:

No data reported

Details on matrix:

No data reported

Details on test conditions:

Test item was dissolved in Tetrahydrofuran to a concentration of 1 g/l, and this was further diluted with mobile phase to concentrations of 10 and 100 mg/l.

Sample No.:

#1

Duration:

7.653 min

Initial conc. measured:

10 other: mg/L test substance

Temp.:

25 °C

Sample No.:

#2

Duration:

7.653 min

Initial conc. measured:

10 other: mg/L test substance

Temp.:

25 °C

Sample No.:

#3

Duration:

7.573 min

Initial conc. measured:

10 other: mg/L test substance

Temp.:

25 °C

Computational methods:

No data reported

Type:

log Koc

Value:

8.5

Temp.:

25 °C

Remarks on result:

other: synthetic solid phase used

Details on results (HPLC method):

The log Koc of the test item is above the highest value of the reference items (4.09) and was extrapolated to a value of 8.5.

Transformation products:

not measured

Statistics:

A calibration curve determined from the 7 reference substances was used to determine the adsorption coefficient. Between the log Koc range of 1.25 and 4.09, the linearity of the method was proven. The log Koc of the test item is above the highest value of the reference items (4.09) and was extrapolated to a value of 8.5.

Sample	Retention Time (min)	Capacity factor	log K	log Koc
10mg/l test substance	7.653	6	0.78	8.5
10mg/l test substance	7.653	6	0.78	8.5
10mg/l test substance	5.573	5.93	0.77	8.4
Mean Value	7.63	5.98	0.78	8.5

Reference Item	Retention Time (min)	Log Koc
Sodium nitrate (dead time)	1.09	n.a.
Acetanilide	2.86	1.25
Methylbenzoate	3.39	1.8
Triadimenol	3.39	2.4
Linuron	3.39	2.59
1,2,3-Trichlorobenzene	3.81	3.16
Pyrazophos	4.04	3.65
Phenanthrene	4.04	4.09

Validity criteria fulfilled:

no

Remarks:

Most of the validity criteria were met, but no reference data were available with results above the obtained value and the purity of the reference substances were not reported.

Conclusions:

The log Koc of the test item is above the highest value of the reference items (4.09) and was extrapolated to a value of 8.5.

Executive summary:

Mollandin (2010) is a GLP-compliant study following OECD guideline 121. The validity criteria were not met as no reference data were available with results above the obtained value and the purity of the reference substances were not reported. The log Koc of the test substance has therefore been extrapolated. This study is considered reliable and suitable as a key study for this endpoint.

Description of key information

The partition coefficient log Koc of di-tert-dodecyl disulfide was determined to be higher than 5.63 in an OECD 117 test. By read-across with di-tert-dodecyl polysulfides, log Koc is considered to be equal to 8.5

Key value for chemical safety assessment

Koc at 20 °C:

316 227 766

Additional information

[LogKoc: 8.5]