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Adsorption / desorption

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Reference
Endpoint:
adsorption / desorption: screening
Type of information:
(Q)SAR
Adequacy of study:
key study
Study period:
22 May 2018
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
results derived from a valid (Q)SAR model and falling into its applicability domain, with adequate and reliable documentation / justification
Justification for type of information:
1. SOFTWARE
EPI Suite v4.11 (EPA Office of Pollution Prevention Toxics and Syracuse Research Corporation (SRC))

2. MODEL (incl. version number)
KOCWIN Program (v2.00)

3. SMILES OR OTHER IDENTIFIERS USED AS INPUT FOR THE MODEL
SMILES code: c1cc(ccc1C(=O)NCCC(=O)O)NN=C2C=CC(=O)C(=C2)C(=O)O

4. SCIENTIFIC VALIDITY OF THE (Q)SAR MODEL
- Defined endpoint: Yes - adsorption coefficient
- Unambiguous algorithm: No
- Defined domain of applicability: Currently there is no universally accepted definition of model domain.  
- Appropriate measures of goodness-of-fit and robustness and predictivity: The following table gives statistical information for the MCI (Molecular Connectivity Index, first-order) training and validation Datasets. The statistics pertain to the experimental log Koc and the MCI estimated log Koc:

MCI Methodology
Training Training Validation
No Corrections with Corrections Data set
number 69 447 158
r2 corr coef 0.967 0.900 0.850
std deviation 0.247 0.340 0.583
avg deviation 0.199 0.273 0.459

The estimation accuracy of the MCI Methodology Training dataset (no corrections) is as follows:

• number = 69
• r2 = 0.967
• std deviation = 0.247
• avg deviation = 0.199

The estimation accuracy of the MCI Methodology Training dataset (with corrections) is as follows:

• number = 447
• r2 = 0.90
• std deviation = 0.34
• avg deviation = 0.273

The residual estimation error of the MCI training datasets is as follows:

Training Estimation Error:
within <= 0.20 - 44.2%
within <= 0.40 - 76.9%
within <= 0.60 - 93.0%
within <= 0.80 - 98.6%
within <= 1.00 - 100%

The estimation accuracy of the MCI Methodology Validation dataset is as follows:

• number = 158
• r2 = 0.850
• std deviation = 0.583
• avg deviation = 0.459

The minimum and maximum values for molecular weight are the following:

Training Set Molecular Weights:
Minimum MW: 32.04
Maximum MW: 665.02
Average MW: 224.4

Validation Molecular Weights:
Minimum MW: 73.14
Maximum MW: 504.12
Average MW: 277.8

- Mechanistic interpretation: Not applicable

5. APPLICABILITY DOMAIN
- Descriptor domain: The Soil Adsorption Coefficient Program (KOCWIN) estimates the soil adsorption coeffiecient (Koc) of organic compounds. The MCI methodology in the KOCWIN Program (v2.00) uses 516 compounds in the training sets and 158 compounds in the validation set. Since Balsalazide acid is an organic chemical it falls within the general applicability domain of the model. Currently there is no universally accepted definition of model domain. Log Koc estimates are less accurate for compounds outside the MW range of the training set compounds, and/or that have more instances of a given fragment than the maximum for all training set compounds.  It is also possible that a compound may have a functional group(s) or other structural features not represented in the training set, and for which no fragment coefficient or correction factor was developed. 
- Structural and mechanistic domains: Most of the functional groups/ structural features of Balsalazide acid are represented in the training set.
- Similarity with analogues in the training set: Not determined

6. ADEQUACY OF THE RESULT
The molecular weight of Balsalazide acid falls within the applicability domain of the model and most of the functional groups/ structural features are represented in the training set. Therefore, it can be considered that the KOCWIN Program (v2.00) result is indicative of the adsorption coefficient of Balsalazide acid.
Qualifier:
no guideline followed
Principles of method if other than guideline:
- Software tool used including version: EPI Suite v4.11 (EPA Office of Pollution Prevention Toxics and Syracuse Research Corporation (SRC))
- Model(s) used: KOCWIN Program (v2.00)
- Model description: see field 'Justification for type of information'
- Justification of QSAR prediction: see field 'Justification for type of information'
GLP compliance:
no
Specific details on test material used for the study:
SMILES code: c1cc(ccc1C(=O)NCCC(=O)O)NN=C2C=CC(=O)C(=C2)C(=O)O
Key result
Sample No.:
#1
Type:
Koc
Value:
89.3 L/kg
Remarks on result:
other: QSAR predicted value
Validity criteria fulfilled:
not applicable
Conclusions:
The adsorption coefficient of Balsalazide acid was estimated to be 89.3 L/kg.

Description of key information

The adsorption coefficient of Balsalazide acid was estimated to be 89.3 L/kg using prediction software.

Key value for chemical safety assessment

Koc at 20 °C:
89.3

Additional information