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Environmental fate & pathways

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
Justification for type of information:
REPORTING FORMAT FOR THE ANALOGUE APPROACH
In this justification, the read-across (bridging) concept is applied. Please refer to a full version of Read-across statement attached in the section 13 "Assessment reports".

1. HYPOTHESIS FOR THE ANALOGUE APPROACH
The underlying hypothesis for the read-across is that the target and the source substance have similar toxicological properties (including the same target organs) due to their structural similarity, resemblance to their chemical reactivity, and therefore a similar mode of action.
The source substance 1,4-diisopropylbenzene is a structural isomer of the target substance 1,3- diisopropylbenzene. The only difference between the target and this source substance is the position of the two isopropyl groups. While for 1,4-diisopropylbenzene both isopropyl groups are in para position at the benzene ring for 1,3-diisopropylbenzene they are in meta position.
The justification is based on similarity of chemical structure, physical-chemical properties and toxicokinetic behavior. As a conclusion, it is scientifically justified to address the endpoint Adsorption / desorption with data on this substance.

2. SOURCE AND TARGET CHEMICAL(S) (INCLUDING INFORMATION ON PURITY AND IMPURITIES)


source substance: 1,4-diisopropylbenzene (or p-DIPB)
structural formula: C12H18
Smiles: CC(C)c1ccc(cc1)C(C)C
Molecular weight: 162
CAS 100-18-5
EC No 202-826-9
purity: not specified

target substance: 1.3-diisopropylbenzene (or m-DIPB)
structural formula: C12H18
Smiles: CC(C)c1cccc(c1)C(C)C
Molecular weight: 162 g/mol
CAS 99-62-7
EC No 202-773-1
purity: not specified

No additional information is available on purity of the source and the target substances. Both substances are normally of high purity, containing only minor amounts of impurities that do not influence the read-across validity.

3. ANALOGUE APPROACH JUSTIFICATION
Please refer to the full version of the read-across statement attached in the section 13 "Assessment reports".


4. DATA MATRIX
Please refer to the full version of the read-across statement attached in the section 13 "Assessment reports".
Reason / purpose for cross-reference:
read-across source
Type:
log Koc
Value:
3.8
Temp.:
30 °C
Remarks on result:
other: Recorded temperature was column temperature.
Details on results (HPLC method):
- Retention times of reference substances used for calibration:
Formamide: 1.985 min. (Dead-time)
acetanilide: 2.343 min.
phenol: 2.405 min.
atrazine: 2.743 min.
isoproturon: 2.971 min.
triadimenol: 3.141 min.
linuron: 3.503 min.
naphthalene: 4.451 min.
endosulfan-diol: 3.489 min.
phenanthrene: 5.258 min.
α-endosulfan: 6.006 min.
phenanathrene: 7.315 min.
DDT: 14.818 min.
- Details of fitted regression line (log k' vs. log Koc):
y = 0.3374 x- 1.0141 R^2 = 0.9554
- Average retention data for test substance: 5.658 min.

The retention times, capacity factors and logio Koc values determined for the sample are shown in the following table:

 Peak    Retention time (mins)        Capacity factor (k)      Log10 k     Log10 Koc    
injection 1  injection 2  Mean 
 1 5.661  5.656  5.658  1.85  0.267  3.80 

 

Log10 Koc : 3.80

Adsorption coefficient: 6.28* 103

Discussion

The mobile phase was used at an approximately neutral pH as the test item had no dissociation constants within the environmentally relevant pH range.

Conclusions:
The adsorption coefficient (Koc) of the test item has been determined to be 6.28 x 103, log10 Koc 3.80.
Executive summary:

6.28 x 103, log10Koc 3.80, 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.

Description of key information

6.28 x 103, log10Koc 3.80, 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.

Key value for chemical safety assessment

Koc at 20 °C:
6 280

Additional information

The adsorption coefficient (Koc) of p-diisopropylbenzene, a close analogue of m-diisopropylbenzene has been determined in a study according to EU Method C.19 (Estimation of the Adsorption Coefficient (KOC) on Soil and Sewage Sludge Using High Performance Liquid Chromatography (HPLC)). The mobile phase was used at an approximately neutral pH as the test item had no dissociation constants within the environmentally relevant pH range.


The adsorption coefficient (Koc) of the test item has been determined to be 6.28 x 10E3, log10 Koc 3.80.