Octadecene, reaction products with hexadecene, hydrogenated

Adsorption / desorption

Link to relevant study record(s)

Reference

Endpoint:

adsorption / desorption: screening

Remarks:

other: QSAR assessment using US EPA On-Line EPI Suite™ KOCWIN v2.00 model

Type of information:

calculation (if not (Q)SAR)

Remarks:

estimated by calculation

Adequacy of study:

key study

Study period:

January 2020

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: see 'Remark'

Remarks:

Validated QSAR calculation method, using EPIWIN suite, KOCWIN v2.00 model model. A QPRF is attached. The substance is recognised as part of the rulebase utilised by the EPI Suite model data set, and is in model Applicability Domain. Further details can be found within the appended report below or at http://www.epa.gov/oppt/exposure/pubs/episuite.htm. This system is recognised in ECHA Guidance document CHAPTER R.6 – QSARS AND GROUPING OF CHEMICALS, Pg 47

Qualifier:

no guideline followed

Principles of method if other than guideline:

The substance is a hydrocarbon UVCB. Standard tests for assessment of adsorption are intended for single substances and are not appropriate for this complex substance. It is unlikely that a study result would give anything other than a “greater than” limit value of the highest value available in the test. This endpoint is therefore characterized using quantitative structure property relationships for representative hydrocarbon structures that could be present within this UVCB substance. 18 proposed molecules are assessed, in order to provide a suitable range of likely values associated with the substance. Details on the KOCWIN v2.00 model programme are detailed below under "methods".

GLP compliance:

no

Type of method:

other: QSAR assessment using US EPA On-Line EPI Suite™ KOCWIN v2.00 model

Media:

other: QSAR assessment using US EPA On-Line EPI Suite™ KOCWIN v2.00 model

Specific details on test material used for the study:

Details on properties of test surrogate or analogue material (migrated information):Not applicable - QSAR assessment.

Radiolabelling:

no

Test temperature:

Not applicable - QSAR assessment.

Details on study design: HPLC method:

Not applicable - QSAR assessment.

Analytical monitoring:

not required

Details on sampling:

Not applicable - QSAR assessment.

Details on matrix:

Not applicable - QSAR assessment.

Details on test conditions:

Not applicable - QSAR assessment.

Computational methods:

The Soil Adsorption Coefficient Program (KOCWIN) estimates the soil adsorption coeffiecient (Koc) of organic compounds. Koc can be defined as "the ratio of the amount of chemical adsorbed per unit weight of organic carbon (oc) in the soil or sediment to the concentration of the chemical in solution at equilibrium" (Lyman, 1990); it is represented by the following equation (Lyman, 1990): Koc = (ug adsorbed/g organic carbon) / (ug/mL solution)The units of Koc are typically expressed as either L/kg or mL/g.Koc provides an indication of the extent to which a chemical partitions between solid and solution phases in soil, or between water and sediment in aquatic ecosystems. Estimated values of Koc are often used in environmental fate assessment because measurement of Koc is expensive. Traditional estimation methods rely upon the octanol/water partition coefficient or related parameters, but the first-order molecular connectivity index (MCI) has been used successfully to predict Koc values for hydrophobic organic compounds (Sabljic, 1984, 1987; Bahnick and Doucette, 1988). The original KOCWIN program (PCKOC) used MCI and a series of group contribution factors to predict Koc (Meylan et al., 1992). This group contribution method was shown to outperform traditional estimation methods based on octanol/water partition coefficients and water solubility. Since the introduction of the original PCKOC program in 1992, the number of available experimental Koc values has grown significantly. Using an expanded experimental dataset and the original PCKOC methodology, the QSAR equations were re-regressed to derive updated coefficient values. In addition, several new group contribution factors (correction factors) were added to improve estimation accuracy. Also, the updated KOCWIN program includes a separate Koc estimate based upon Log Kow (rather than MCI). A brief description of the estimation methodology and accuracy is presented in the Methodology section and Accuracy section of the programme.KOCWIN requires only a chemical structure to make these predictions. Structures are entered into KOCWIN by SMILES (Simplified Molecular Input Line Entry System) notations. The following journal article explains the MCI prediction methodology and its use:(1) Meylan, W., P.H. Howard and R.S. Boethling, "Molecular Topology/Fragment Contribution Method for Predicting Soil Sorption Coefficients", Environ. Sci. Technol. 26: 1560-7 (1992).Journal abstract:"The first-order molecular connectivity index (MCI) has been successfully used to predict soil sorption coefficients (Koc) for nonpolar organics, but extension of the model to polar compounds has been problematic. To address this, we developed a new estimation method based on MCI and series of statistically derived fragment contribution factors for polar compounds. After developing an extensive database of measured Koc values, we divided the dataset into a training set of 189 chemicals and an independent validation set of 205 chemicals. Two linear regressions were then performed. First, measured log Koc values for nonpolar compounds in the training set were correlated with MCI. The second regression was developed by using the deviations between measured log Koc and the log Koc estimated with the nonpolar equation and the number of certain structural fragments in the polar compounds. The final equation for predicting log Koc accounts for 96% and 86% of the variation in the measured values for the training and validation sets, respectively. Results also show that the model outperforms and covers a wider range of chemical structures than do models based on octanol-water partition coefficients (Kow) or water solubility."

Key result

Type:

log Koc

Value:

>= 8.714 - <= 17.01 dimensionless

Temp.:

25 °C

Remarks on result:

other: Calculated range of values using EPIWIN KOCWIN v2.00 model

Details on results (HPLC method):

Not applicable - QSAR assessment.

Adsorption and desorption constants:

Not applicable - QSAR assessment.

Recovery of test material:

Not applicable - QSAR assessment.

Concentration of test substance at end of adsorption equilibration period:

Not applicable - QSAR assessment.

Concentration of test substance at end of desorption equilibration period:

Not applicable - QSAR assessment.

Details on results (Batch equilibrium method):

Not applicable - QSAR assessment.

Statistics:

Not applicable - QSAR assessment.

Tabulated data for the QSAR assessment.

Structure	MW	Formula	Smile	KOCWIN c2.00 (Log Koc)
Dimers
1	450.88	C32H66	CCCCCCC(C)CCCCCCCCC(CCCCC)CC(CC)CCC(C)CC	8.7142
2	450.88	C32H66	CCCCC(CCC(CC)CCC)CC(C)CCCCCCCCCCCCC(C)CC	8.7142
3	450.88	C32H66	CCCCCCCCCCCCCCC(C)C(CCCC)CCCCCCC(C)CCC	8.7585
4	450.88	C32H66	CCCCC(CCCCCCCCCCCCC(C)CC)CC(CCC)CCC(C)CC	8.7142
5	450.88	C32H66	CCCCCCCCCCCCCCC(C)C(CCCC)CCCCCC(C)CCCC	8.7585
6	450.88	C32H66	CCCCCCCCCCCC(CCCC)CCCCCCCCCCCC(C)CCC	8.805
7	450.88	C32H66	CCCCCC(CCC)CCCCC(C)CC(C)CCCCCCCCCCCC(C)C	8.6745
8	450.88	C32H66	CCCCCCCCCCCCCC(C)CC(CCCC)CCCCC(C)CCCCC	8.7497
Trimers
9	675.312	C48H98	CCCCCCCCCC(CCCC)CC(CCCCC)CCCCCCCCCCCC(CC)C(CCC)CCCCCCCCC	12.933
10	675.312	C48H98	CCCCCCCCCCCC(CCCC)C(CCC)CCCCCCCCCCCCCC(CCCC)CCC(CC)CCCCC	12.933
11	675.312	C48H98	CCCCCCCCCCCCCCC(C)CCCCCCCCCCCCCCC(C)C(CCCC)CCCCCCCCCCC	12.9289
12	675.312	C48H98	CCCCCCCCCCCC(CCC)C(CCCCCCCC(C)CC)CCCCC(CCCC)CC(CCC)CCCCCC	12.617
13	675.312	C48H98	CCCCCCCCCC(CCCCCC(CCCC)CCCCCC(C)CCCC)C(CCC)CCCCCCCCCCC(C)C	12.838
14	675.312	C48H98	CCCCCCCCCCCCCCC(C)C(CCCCCCCCCCC(C)CCC)C(CCCC)CCCCCCCCCCC	12.9021
15	675.312	C48H98	CCCCCCCCCCCC(CCCC)C(CCCCCCCC(CC)CCCCCCC(CCC)CCCCC)CCC(C)CC	12.8776
16	675.312	C48H98	CCCCCCCCCCCCCCC(C)C(CCCC)CCCCCCCCC(C)CC(CCCC)CCCCC(C)CCCCC	12.838
Tetramer
17	899.744	C64H130	CCCCCCCCCCCCCCC(C)C(CCCC)C(CCCCCCCC(C)CC(CCCC)CCCCC(C)CCCCC)C(CCCCCCC)CCCCC(C)C	16.6191
18	899.744	C64H130	CCCCCCCCCCCCC(CCC)C(CCCCCCCC)CCCCCC(C)C(CCCCCCCCCCC(C)CCC)C(CCCC)CCCCCCCCCCC	17.0102

Validity criteria fulfilled:

yes

Conclusions:

Using the US EPA On-Line EPI Suite™ KOCWIN v2.00 model, the log Koc range is predicted to be 8.7142 to 17.0102. This is anticipated to be appropriate, based on the predicted water solubility and hydrocarbon nature of the substance.

Executive summary:

The substance is a hydrocarbon UVCB. Standard tests for assessment of adsorption are intended for single substances and are not appropriate for this complex substance. It is unlikely that a study result would give anything other than a “greater than” limit value of the highest value available in the test. This endpoint is therefore characterized using quantitative structure property relationships for representative hydrocarbon structures that could be present within this UVCB substance. 18 proposed molecules are assessed, in order to provide a suitable range of likely values associated with the substance.

Using the US EPA On-Line EPI Suite™ KOCWIN v2.00 model, the log Koc range is predicted to be 8.7142 to 17.0102. This is anticipated to be appropriate, based on the predicted water solubility and hydrocarbon nature of the substance.

Log Koc can provide insight as to whether a material will cling to soils or sediments in water and whether they will desorb or be tightly bound. Based on information from NTIS ((Review of Exposure Assessment Guidelines, September 1996), approximate indications of relative soil absorption potential are as follows:

Low potential: Koc = 1 to 100, log Koc = 0 - 2
Moderate potential: Koc = 100 to 10,000, log Koc = 2 - 4
High potential: Koc = 10,000 to 10,000,000, log Koc 4 - 7
A high potential would indicate that a material would bind tightly to soils and sediments and thus, reduce overall exposure potential.

Key value for chemical safety assessment

Koc at 20 °C:

0.94