1,8-naphthylenediamine

Adsorption / desorption

Link to relevant study record(s)

Reference

Endpoint:

adsorption / desorption: screening

Remarks:

adsorption

Type of information:

(Q)SAR

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

accepted calculation method

Justification for type of information:

1. SOFTWARE
Individual model KOCWIN included in the Estimation Programs Interface (EPI) Suite.

2. MODEL (incl. version number)
KOCWIN v2.00 included in EPISuite v 4.11, 2000-2012.

3. SMILES OR OTHER IDENTIFIERS USED AS INPUT FOR THE MODEL
A SMILES notation was entered in the initial data entry screen. In the structure window, the molecular weight, structural formula and the structure of the input SMILES notation is shown.

4. SCIENTIFIC VALIDITY OF THE (Q)SAR MODEL
a. Defined endpoint: Organic carbon partition coefficient, given as log Koc.
b. Dependent variable: KOCWIN estimates log Koc with two separate estimation methodologies: (1) Estimation using first order Molecular Connecitivity Index (MCI), (2) Estimation using log Kow (octanol-water partition coefficient)
c. Algorithm:
Log Koc according to MCI method is calculated using the formula:
log Koc = 0.5213 MCI + 0.60 + ΣPfN
(ΣPfN is the sum of all relevant correction factor coefficients multiplied by the number (N) of that factor in each chemical structure)
Log Koc according to the log Kow method is calculated using two formulas (depending on the polarity of the substance):
log Koc = 0.8679 log Kow - 0.0004 (Non-polar substances)
log Koc = 0.55313 log Kow + 0.9251 + ΣPfN (polar substances)
d. Descriptor values:
Log Kow method:
For estimation of log Koc according to log Kow method an experimentally determined log Kow of 1.78 was used (MITI-online, 2012).
e. Applicability domain: The minimum and maximum values for molecular weight are the following:
Training Set Molecular Weights: 32.04-665.02 g/mol,
Validation Set Molecular Weights: 27.03-991.15 g/mol
f. Statistics for goodness-of-fit:

Statistical accuracy of MCI methodology for training and validation set:
i. Training without corrections:
Number: 69
R^2 correction coefficient: 0.967
Standard deviation (log Koc): 0.247
Average deviation (log Koc): 0.199
ii. Training with corrections:
Number: 447
R^2 correction coefficient: 0.900
Standard deviation (log Koc): 0.340
Average deviation (log Koc): 0.273
iii. Validation data set:
Number: 158
R^2 correction coefficient: 0.850
Standard deviation (log Koc): 0.583
Average deviation (log Koc): 0.459

Statistical accuracy of Log Koc methodology:
i. Training without corrections:
Number: 68
R^2 correction coefficient: 0.877
Standard deviation: 0.478
Average deviation: 0.371
ii. Training with corrections:
Number: 447
R^2 correction coefficient: 0.855
Standard deviation (log Koc): 0.396
Average deviation (log Koc): 0.307
iii. Validation data set:
Number: 150
R^2 correction coefficient: 0.778
Standard deviation (log Koc): 0.679
Average deviation (log Koc): 0.494

g. Mechanistic interpretation: Log Koc is estimated based on the likeliness of a substance for sorption to surfaces of soil/sediment particles. This characteristic is triggered by lipophilic character of substances but may be modified by certain molecular fragments that need to be considered by application of correction factors. The Log Koc is a physical inherent property used extensively to describe a chemical’s likeliness to adsorb to organic carbon.
h. The uncertainty of the prediction (OECD principle 4): 1,8-naphthylenediamine is not highly complex and the rules applied for the substance appear appropriate. An individual uncertainty for the investigated substance is not available.

5. APPLICABILITY DOMAIN
a. Descriptor domains:
i. Molecular weights: With a molecular weight of 158.2 g/mole the substance is within the range of the training set (32-665 g/mole) as well as in the range of the validation set (27-991 g/mole).
ii. Structural fragment domain: Regarding the structure of 1,8-naphthalenediamine the fragment descriptors found by the program are complete and listed in Appendix D (KOCWIN Fragment and Correction Factor descriptors). For log Koc estimation according to MCI method no fragment descriptors were applied. For estimation of log Koc according to log Kow method the log Kow of 1.78 (experimentally determined, MITI-online, 2012) was used.
iii. Mechanism domain: No information available.
iv. Metabolic domain: Not relevant.
b. Structural analogues: No information available
i. Considerations on structural analogues: No information available

6. ADEQUACY OF THE RESULT
a. Regulatory purpose: The data may be used under any regulatory purpose.
b. Approach for regulatory interpretation of the model result: If no experimental data are available, the estimated value may be used to fill data gaps needed for hazard and risk assessment, classification and labelling and PBT / vPvB assessment. Further the value is used for other calculations.
c. Outcome: The prediction of organic carbon partition coefficient yields a useful result for further evaluation.
d. Conclusion: The result is considered as useful for regulatory purposes.

Guideline:

other: REACH guidance QSARs R6, May/July 2008

Principles of method if other than guideline:

Estimation Program Interface EPI-Suite version 4.11: KOCWIN (v2.00) for the estimation of the organic carbon-normalized sorption coefficient for soil and sediment (Koc).
The Estimation Program Interface was developed by the US Environmental Agency's Office of Pollution Prevention and Toxics, and Syracuse Research Corporation (SRC). © 2000 - 2012 U.S. Environmental Protection Agency for EPI SuiteTM (Published online in November 2012).

GLP compliance:

no

Type of method:

other: Estimation

Media:

soil

Radiolabelling:

no

Type:

log Koc

Value:

3.62 dimensionless

Remarks on result:

other: calculation (MCI method)

Type:

log Koc

Value:

1.54 dimensionless

Remarks on result:

other: calculation (Log Kow method)

Phase system:

other: Koc

Type:

other: Koc

Value:

35.03 L/kg

Remarks on result:

other: calculation (logKow method)

Phase system:

other: Koc

Type:

other: Koc

Value:

4 140 L/kg

Remarks on result:

other: calculation (MCI method)

Validity of the model:

1. Defined Endpoint: Organic carbon partition coefficient, given as logarithmic Koc and Koc

2. Unambigous algorithm:

For Log Koc estimation according to MCI method no fragment descriptors were applied.

For estimation of logKoc according to the logKow method the estimated logKow of 1.78 as calculated by the program was used.

3. Applicable domain: With a molecular weight of 158.2 g/mol the substance is within the range of the training set (32 - 665 g/mole) as well as in the validation set (27 - 991 g/mole). Regarding the structure of 1,8-Naphthylenediamine, the fragment descriptors found by the program are complete.

4a. Statistical characteristics (MCI method): N training set without corrections = 69; N training set with correction = 447; N validation set = 158; Correction coefficient of the total training set without corrections r² = 0.967; Correlation coefficient of the total training set with corrections r² = 0.900; Correlation coefficient of the total validation set r² = 0.850.

4b. Statistical characteristics (Kow method): N training set without corrections = 68; N training set with correction = 447; N validation set = 150; Correction coefficient of the total training set without corrections r² = 0.877; Correlation coefficient of the total training set with corrections r² = 0.855; Correlation coefficient of the total validation set r² = 0.778.

5. Mechanistic interpretation: Log Koc is estimated based on the likeliness of a substance for sorption to surfaces of soil/sediment particles. The log Koc is a physical inherent property used extensively to describe a chemical's likeliness to adsob to organic carbon.

6. Adequacy of prediction: The result for 1,8-Naphthylenediamine falls within the applicability domain described above and the estimation rules applied for the substance appears appropriate.

Validity criteria fulfilled:

not applicable

Conclusions:

The QSAR determination of the carbon partition coefficient for 1,8-naphthylenediamine using the model KOCWIN included in the Estimation Program Interface (EPI) Suite v4.11 revealed values of 35.03 L/kg (logKow method) and 4.14 x 10E3 L/kg (MCI method) for the unaffected molecule of the substance as any decomposition (e.g. hydrolysis) of the substance is not taken into account by the program.

Executive summary:

The organic carbon partition coefficient (Koc) for 1,8-naphthylenediamine was predicted using the QSAR calculation of the Estimation Program Interface (EPI) Suite v 4.11. The Koc was estimated to be 35.03 L /kg (logKow method), and 4.14 x 10E3 L/kg (MCI method). The results relate to the unaffected molecule of the substance as any decomposition (e.g. hydrolysis) of the substance is not taken into account by the program.

Based on structural properties of 1,8-naphthylenediamine, the predicted vale for log Koc = 3.62 using MCI method is more likely than the predicted value using log Kow method. It is assumed that the amino groups of 1,8-Naphthylenediamine cause ionic interactions with soil components that seem to be predicted more reliable by MCI method.

Description of key information

The organic carbon partition coefficient (Koc) for 1,8-naphthylenediamine was predicted using the QSAR calculation of the Estimation Program Interface (EPI) Suite v 4.11. The Koc was estimated to be 35.03 L /kg (logKow method), and 4.14 x 10E3 L/kg (MCI method). The results relate to the unaffected molecule of the substance as any decomposition (e.g. hydrolysis) of the substance is not taken into account by the program.

Based on structural properties of 1,8 -naphthylenediamine, the predicted vale for log Koc = 3.62 using MCI method is more likely than the predicted value using log Kow method. It is assumed that the amino groups of 1,8-naphthylenediamine cause ionic interactions with soil components that seem to be predicted more reliable by MCI method.

Key value for chemical safety assessment

Koc at 20 °C:

4 140

Additional information

[LogKoc: 3.62]