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Reference
Endpoint:
adsorption / desorption: screening
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
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))
Principles of method if other than guideline:
To determine Adsorption coefficient (KOC) on soil and on sewage sludge of the 4-nitro-o-toluidine (CAS No. 99-52-5) using HPLC.
GLP compliance:
no
Type of method:
HPLC estimation method
Media:
soil/sewage sludge
Specific details on test material used for the study:
- IUPAC name 2-methyl-4-nitroaniline
- Name of test material: 4-nitro-o-toluidine
- Molecular formula: C7H8N2O2
- Molecular weight: 152.152 g/mol
- Physical state: Solid
- SMILES: c1(cc(c(N)cc1)C)[N+](=O)[O-]
- InChI: 1S/C7H8N2O2/c1-5-4-6(9(10)11)2-3-7(5)8/h2-4H,8H2,1H3

SOURCE OF TEST MATERIAL
- Source and lot/batch No.of test material:M975

STABILITY AND STORAGE CONDITIONS OF TEST MATERIAL
- Storage condition of test material:Ambient Temp (23 to 27 °C) (Keep container tightly closed in a dry & wellventilated place. Store in cool place. Do not expose to air, light & moisture.)
- Stability under test conditions:Stable in recommended storage conditions
Radiolabelling:
not specified
Test temperature:
25°C
Details on study design: HPLC method:
The solutions of the test substance and reference substances were prepared in the mobile phase. Each of the reference substance and test substance were analysed by HPLC at 210 nm.
After equilibration of the HPLC system, Urea was injected first, the reference substances were injected in duplicate, followed by the test chemical solution in duplicate. Reference substances were injected again after test sample, no change in retention time of reference substances was observed.
Retention time tR were measured, averaged and the decimal logarithms of the capacity factors k were calculated. The graph was plotted between log Koc versus log k(Annex - 2).The linear regression parameter of the relationship log Koc vs log k were also calculated from the data obtained with calibration samples and therewith, log Koc of the test substance was determined from its measured capacity factor.
Operating Conditions:
HPLC Model No. : Agilent Technologies,1260 Infinity
Flow Rate : 1.0 mL/min
Column : ZORBAX Eclipse Plus C18, 4.6×100mm, 3.5 μm
Mobile phase : Acetonitrile: water (55:45)
Temperature : 25°C
Detector : Diode Array Detector @210nm
Injector : Autosampler
Injector volume : 10μl
Data Acquisition software : ChemStationOpen lab Control Panel
Details on test conditions:
A test item solution was prepared by accurately weighing 4 mg of test item and diluted with acetonitrile up to 10 ml. Thus, the test solution concentration was 400 mg/l. The pH of test substance was 4.78.
Key result
Type:
log Koc
Value:
2.087 dimensionless
pH:
4.78
Temp.:
25 °C
Remarks on result:
other: reported as 2.0875 ± 0.0002
Transformation products:
not specified

Test substance

4-nitro-o-toluidine

K

Log k

Log Koc

by Generalized Calibration

Graph

Mean of Log Koc ± S.D.

tR1

1.807

1.0372

0.0159

2.0873

2.0875 ± 0.0002

tR2

1.808

1.0372

0.0163

2.0876

Validity criteria fulfilled:
yes
Conclusions:
The Adsorption Coefficient of test substance 4-nitro-o-toluidine (CAS No. 99-52-5) was determined as per the HPLC method (OECD Guideline-121). The Log Koc value was found to be 2.0875 ± 0.0002 at 25°C.
Executive summary:

The adsorption coefficient Koc in soil and in sewage sludge 4-nitro-o-toluidine(CAS No.99-52-5) was determined by the Reverse Phase High Performance Liquid Chromatographic method according to OECD Guideline No. 121 for testing of Chemicals. The reference substances were chosen according to functional group similarity with the test substance and calibration graph prepared. The reference substances were 4 -methylaniline, aniline, nitrobenzene, xylene, ethylbenzene and toluene, having Koc value ranging from 1.9 to 2.649. The Log Koc value was found to be 2.0875 ± 0.0002 at 25°C.

Description of key information

The adsorption coefficient Koc in soil and in sewage sludge 4-nitro-o-toluidine(CAS No.99-52-5) was determined by the Reverse Phase High Performance Liquid Chromatographic method according to OECD Guideline No. 121 for testing of Chemicals. The reference substances were chosen according to functional group similarity with the test substance and calibration graph prepared. The reference substances were 4 -methylaniline, aniline, nitrobenzene, xylene, ethylbenzene and toluene, having Koc value ranging from 1.9 to 2.649. The Log Koc value was found to be 2.0875 ± 0.0002 at 25°C.

Key value for chemical safety assessment

Koc at 20 °C:
122.32

Additional information

Four studies including experimental study and predicted data from validated models for adsorption (KOC) endpoint of target chemical 2-methyl-4-nitroaniline (Cas no. 99-52-5) were summarized as follows:

 

First study from experimental report by UERL laboratory; 2017 which suggest the adsorption coefficient Koc in soil and in sewage sludge 4-nitro-o-toluidine(CAS No.99-52-5) was determined by the Reverse Phase High Performance Liquid Chromatographic method according to OECD Guideline No. 121 for testing of Chemicals. The reference substances were chosen according to functional group similarity with the test substance and calibration graph prepared. The reference substances were 4 -methylaniline, aniline, nitrobenzene, xylene, ethylbenzene and toluene, having Koc value ranging from 1.9 to 2.649. The Log Koc value was found to be 2.0875 ± 0.0002 at 25°C.

 

Above results also supported by prediction using KOCWIN model (v2.00) of EPI suite which indicated the adsorption value of 2-methyl-4-nitroaniline was estimated as Koc 178.6 L/kg (log Koc = 2.25) by means of MCI method at 25 deg.C. This Koc value indicates that the substance 2-methyl-4-nitroaniline has a low sorption to soil and sediment and therefore have moderate migration potential to groundwater.

 

Another prediction model i.e Chemspider - ACD/PhysChem Suite for target indicate the soil adsorption coefficient i.e Koc value of test substance 2-methyl-4-nitroaniline was estimated to be 161.70 (log koc: 2.20) at pH 5.5 and 7.4 and temp.25 deg.C Koc values at mentioned pH indicates that the substance 2-methyl-4-nitroaniline has slow sorption to soil and sediment and therefore have moderate migration potential to groundwater.

Last study from Scifinder database suggest the soil adsorption coefficient i.e Koc value of test substance 2-methyl-4-nitroaniline was estimated to be 71.0 (Log koc: 1.85) at pH 1, 120 (Log koc: 2.07)at pH 2 and  130 (Log koc:2.11) at pH 3-10 at temperature 25 deg.C. This Koc value at all range of pH condition indicates that the substance 2-methyl-4-nitroaniline has low sorption to soil and sediment and therefore have moderate migration potential to groundwater.

Thus all available studies for adsorption endpoint gives the common conclusion that the test substance 2-methyl-4-nitroaniline (Cas no. 99-52-5) is expected to have moderate mobility in soil and sediment compartment.

[LogKoc: 2.0875]