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Adsorption / desorption

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Reference
Endpoint:
adsorption / desorption: screening
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Study period:
Experimental start: 11/09/09, Experimental end: 15/09/09; Final report: 17/12/09
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: 1a: GLP Guideline study
Justification for type of information:
see read across rationale in Section 13.2
Reason / purpose:
read-across source
Qualifier:
according to
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. certificate)
Type of method:
HPLC estimation method
Media:
sewage sludge
Specific details on test material used for the study:
Details on properties of test surrogate or analogue material (migrated information):
No test surrogate or analogue material.
Radiolabelling:
no
Test temperature:
During the analysis, the temperature was 22 °C.
Details on study design: HPLC method:
Principle of the HPLC Method
The test item is injected on a liquid chromatography system where a partition occurs between the stationary phase of the column and the eluent phase. Chemicals are retained according to their adsorption coefficient.Therefore a relation exists between the retention time and the adsorption coefficient of a chemical product.

The distribution coefficient (Kd) is defined as the ratio of the equilibrium concentrations C of a dissolved test substance in a two-phase system consisting of a sorbent (soil or sewage sludge) and an aqueous phase.
Kd= Csoil/Cwater or Csludge/Cwater
where:

Csoil = concentration of substance in soil at equilibrium (µg.g-1)
Csludge = concentration of substance in sludge at equilibrium (µg.g-1)
Cwater = concentration of substance in water at equilibrium (µg.g-1, µg.ml-1)

The adsorption coefficient Koc is defined as the ratio of the distribution coefficient Kd to the organic carbon content of a sorbent (foc).
Koc=Kd/foc
This coefficient is dimensionless and is usually given in the form of its logarithm to base 10.

A capacity factor k’ is defined by the relation:
K’=(tr-t0)/t0
Where:
tR : HPLC retention time of test and reference substance (minutes)
t0 : HPLC dead time (minutes)
The adsorption coefficient (Koc) is determined through the relation:
LogKoc=a+blogk’
The a and b regression coefficients are obtained by linearly regressing the log of partition coefficients of reference substances against the log of capacity factors of the same substances.

Determination of the Adsorption Coefficient

Dead time t0
The dead time is measured by use of formamide, which is not retained on the column.

Regression equation
A correlation of log k’ versus log Koc is plotted for the appropriate reference substances. The regression equation is performed at regular intervals, so that account can be taken of possible changes in column performance.

At least two determinations are performed and the value retained for log Koc of the test item is the mean of the two values obtained.

For experimental procedure details see "Any other information on materials and mathods incl. tables"
Type:
Koc
Value:
>= 1 259 - <= 63 096
Type:
log Koc
Value:
>= 3.1 - <= 4.8
Details on results (HPLC method):
See "Remarks on results including tables and figures"

   

The results of the adsorption coefficient determination of1,3(4)-BIS(TERT-BUTYLPEROXYISOPROPYL)-BENZENEare given in the following tables (see also the corresponding annex 2):

Products

Mean* Retention

Time (min)

Value of the Capacity

Factor k’

Value of log k’

Value of

log Koc

Formamide

1.89

-

-

-

Acetanilide

2.54

0.3439153

-0.46354845

1.25

Methyl benzoate

3.16

0.6719576

-0.17265808

1.80

Triadimenol

4.11

1.1746033

0.06989117

2.40

Naphtalene

5.08

1.6878308

0.227328879

2.75

Phenanthrene

9.65

4.1058199

0.613399917

4.09

DDT

22.56

10.936509

1.038878672

5.63

* Values were calculated as the mean of 3 determinations.

Using the Capacity factor and the partition coefficient of the reference items, the following calibration curve was obtained:

log Koc= 2.95 log k’ + 2.34           r2= 0.9839

The following table gives the mean log Kocvalues for the 3 peaks of 1,3(4)-BIS(TERTBUTYLPEROXY-ISOPROPYL)BENZENEobtained for 3 determinations:

Peak number

Average retention time, min.

Average

area, %

Average

LogKoc

1

5.29

5.59

3.1

2

13.37

59.74

4.7

3

14.98

34.67

4.8

They were calculated using the precedent regression equation with the corresponding retention time.

These results issued from the 3 determinations are in the guideline tolerance for repeatability (+/- 0.25 log units.).

Validity criteria fulfilled:
yes
Remarks:
See conclusions
Conclusions:
Validity criteria were fulfilled:
The temperature during the measurement did not vary by more than +/- 1°C.
Repeatability - The value of log Koc derived from repeated measurements made under identical conditions and using the same set of reference substances did fall within a range of +/- 0.25 log units.
Reproducibility - If the measurements are repeated with a different set of reference substances, results may differ. Typically, the correlation coefficient for the relationship between log k’ and log Koc for a set of test substances is around 0.9. The correlation coefficient was 0.9839.

The adsorption/desorption behaviour of 1,3(4)-BIS(TERT-BUTYLPEROXYISOPROPYL)BENZENE on soil and sewage sludge was evaluated in a study performed in accordance with OECD testing guideline 121 and GLP requirements.
1,3(4)-BIS(TERT-BUTYLPEROXYISOPROPYL)BENZENE contains 3 components for which three log Koc values were estimated: 3.1; 4.7 and 4.8.
During the analysis, the temperature was 22 °C and the pH value was 6.96.

Executive summary:

The adsorption/desorption behaviour of1,3(4)-BIS(TERT-BUTYLPEROXYISOPROPYL)BENZENEon soil and sewage sludge was evaluated in a study performed in accordance with OECD testing guideline 121 and GLP requirements.

1,3(4)-BIS(TERT-BUTYLPEROXYISOPROPYL)BENZENEcontains 3 components (from 1 to 3).Quality criteria were fulfilled.

The following table gives the percentage of area and the log Kocvalues obtained for each of them.

During the analysis,the temperature was 22°Cand the pH value was 6.96.

Peak number

Average retention time, min.

Average

area, %

Average

LogKoc

1

5.29

5.59

3.1

2

13.37

59.74

4.7

3

14.98

34.67

4.8

Consequently, [1,3(or1,4)-Phenylenebis(1-methylethylidene)]bis[tert-butyl] peroxide is not considered to be mobile in soil.

Description of key information

The adsorption/desorption behaviour of analogous 25155-25-3 1,3(4)-bis(tert-butylperoxyisopropyl)benzene on soil and sewage sludge was evaluated in a study performed in accordance with OECD testing guideline 121 and GLP requirements.

1,3(4)-bis(tert-butylperoxyisopropyl)benzene contains 3 components for which three log Koc values were estimated: 3.1; 4.7 and 4.8.

Key value for chemical safety assessment

Koc at 20 °C:
63 096

Additional information

The adsorption/desorption behaviour analogous of 25155 -25 -3 1,3(4)-bis(tert-butylperoxyisopropyl)benzene on soil and sewage sludge was evaluated in a study performed in accordance with OECD testing guideline 121 and GLP requirements.

1,3(4)-bis(tert-butylperoxyisopropyl)benzene contains 3 components for which three log Koc values were estimated: 3.1; 4.7 and 4.8. During the analysis, the temperature was 22 °C and the pH value was 6.96.

Consequently, [1,3-phenylenebis(1-methylethylidene)]bis[tert-butyl] peroxide is not considered to be mobile in soil.