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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
Justification for type of information:
Experimental test result performed using standard OECD test guidelines
Qualifier:
according to guideline
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:
Reverse Phase High Performance Liquid Chromatography on Octadecyl-modified silica based stationary phase is used.
Partitioning on the column occurs in order of hydrophobicity when a suitable mobile phase is used. From relationship between the measured retention times and the adsorption coefficient on organic matter of reference substances, the sorption coefficient of the test substance is calculated.
GLP compliance:
no
Type of method:
HPLC estimation method
Media:
soil/sewage sludge
Specific details on test material used for the study:
-Name of the test material: 2,4,6-trichloroaniline
- Molecular formula :C6H4Cl3N
- Molecular weight :196.464
- Smiles notation:Nc1c(Cl)cc(Cl)cc1Cl
- InChl :1/C6H4Cl3N/c7-3-1-4(8)6(10)5(9)2-3/h1-2H,10H2
-Substance type: Organic
-Physical state: solid
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 substances and test substance were analysed by HPLC at 210 nm.
After equilibration of the HPLC system,Urea was injected first, the reference substanceswere 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 substanceswas observed.
Retention time tR were measured, averaged and the decimal logarithms of the capacity factors k were calculated. The graph was plotted between log Kocversus 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.

Chromatographic Conditions:
•HPLC Model No. :Agilent Technologies,1260 Infinity
•Flow Rate :1.0ml/min
•Column :ZORBAX Eclipse Plus C18, 4.6×250mm, 5 µm
•Mobile phase :Methanol:water (55:45)
•Temperature :25°C
•Detector :Diode Array Detector @210nm
•Injector :Autosampler
•Injector volume :20µl
•Data Acquisition software :ChemStationOpen lab Control Panel
•Analysis time :30min
Analytical monitoring:
not specified
Key result
Type:
log Koc
Value:
3.466 dimensionless
Temp.:
25 °C
Remarks on result:
other: other details not avaiable
Transformation products:
not specified

Reference substance

Log Koc

tR1

tR2

tR3

MeantR± S.D.

k

Log k

Urea

-

2.367

2.368

2.365

2.366±0.001

-

-

Benzamide

1.239

3.326

3.322

-

3.324±0.002

0.4049

-0.392

N-methylbenzamide

1.3

3.603

3.608

-

3.6055±0.003

0.5238

-0.28

4-Nitrobenzamide

1.43

3.744

3.751

-

3.7475±0.004

0.5838

-0.233

N,N-dimethylbenzamide

1.52

4.294

4.296

-

4.295±0.001

0.8153

-0.088

4-methylaniline(p-Tolouidine)

1.9

5.192

5.2

-

5.196±0.001

1.196

0.077

4-chloroaniline

1.96

6.072

6.068

-

6.07±0.005

1.5655

0.194

N-methylaniline

2.28

6.548

6.559

-

6.5535±0.002

1.7698

0.247

Nitrobenzene

2.35

7.703

7.697

-

7.7±0.004

2.254

0.352

2 - nitrophenol

2.47

7.558

7.551

-

7.5545±0.004

2.192

0.34

phenanthrene

4.09

128.943

128.869

-

128.906±0.052

53.482

1.728

Test substance

2,4,6-trichloroaniline

K

Log k

Log Koc

by Generalized Calibration Graph

Mean of LogKoc± S.D.

tR1

41.027

16.340

1.213

3.469

3.466± 0.004

tR2

40.664

16.186

1.209

3.463

Validity criteria fulfilled:
not specified
Conclusions:
The adsorption coefficient of test substance 2,4,6-trichloroaniline(CAS No.634-93-5)was determined as per the HPLC method (OECD Guideline-121). The Log Koc value was determined to be 3.466± 0.004 at 25°C. By considering log Koc value it can be concluded that test chemical has moderate sorption to soil and sediment and therefore has slow migration potential to ground water.
Executive summary:

The adsorption coefficient (Log Koc) on soil and on sewage of 2,4,6-trichloroaniline(CAS No.634-93-5) 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 estimated Kocrange of the test substance and generalized calibration graph was prepared. The reference substances were 4 chloroaniline, 4 methylaniline, N methylaniline, 2 Nitrophenol, Nitrobenzene, 4-Nitrobenzamide, N,N-dimethylbenzamide, N-methylbenzamide, Benzamide, phenanthrene having Kocvalue ranging from 1.239 to 4.09.

TheLog Kocvalue was determined to be 3.466± 0.004 at 25°C temperature. By considering log Koc value it can be concluded that test chemical has moderate sorption to soil and sediment and therefore has slow migration potential to ground water.

Description of key information

The adsorption coefficient of test substance 2,4,6-trichloroaniline (CAS No.634-93-5) was determined as per the HPLC method (OECD Guideline-121). The Log Koc value was determined  to be 3.466± 0.004 at 25°C. By considering log Koc value it can be concluded that test chemical has moderate sorption to soil and sediment and therefore has slow migration potential to ground water.

Key value for chemical safety assessment

Koc at 20 °C:
2 924

Additional information

Various experimental studies from different journals and experimental report have been reviewed for adsorption and desorption endpoint of test chemical 2,4,6-trichloroaniline(CAS No.634-93-5).

 

The first study was experimental report (2015) in this study the adsorption coefficient (Log Koc) on soil and on sewage of 2,4,6-trichloroaniline(CAS No.634-93-5) 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 estimated Kocrange of the test substance and generalized calibration graph was prepared. The reference substances were 4 chloroaniline, 4 methylaniline, N methylaniline, 2 Nitrophenol, Nitrobenzene, 4-Nitrobenzamide, N,N-dimethylbenzamide, N-methylbenzamide, Benzamide, phenanthrene having Kocvalue ranging from 1.239 to 4.09.

The Log Kocvalue was determined to be 3.466± 0.004 at 25°C temperature.

By considering log Koc value it can be concluded that test chemical has moderate sorption to soil and sediment and therefore has slow migration potential to ground water.

 

 

Next study was reviewed from jouranal Environmental Pollution (2005) in this study the Batch experiments have been performed in order to evaluate the ability of the two reference clays kaolinite (KGa-1) and Na montmorillonite (SWy-1) to retain 2, 4, 6-trichloroaniline. 100 mL of solutions of test chemical 2,4,6-trichloroaniline was put in contact under constant agitation with 2.0 g of, respectively kaolinite and Na-montmorillonite. The experiments have been performed at four concentration levels (1.0, 2.5, 5.0 and 10.0 mg/L) in a pH range between 5.0 and 5.5 for kaolinite and between 8.8 and 9.3 for Na montmorillonite.

The Kd (L g-1) value for the test substance 2, 4, 6- trichloroaniline were determined to be 0.0389 and 0.0488 for kaolinite (KGa-1) and Na montmorillonite (SWy-1) clays respectively. The test chemical 2, 4, 6- trichloroaniline is sorbed by clay standard kaolinite and Na-montmorillonite at different extents and likely by different mechanisms. The test chemical 2,4,6-trichloroaniline showed 8 % adsorption on clay standard kaolinite at all four concentrations of test chemicals (10, 5, 2.5 and 1.0 mg/L) , 10 % adsorption on clay Na-montmorillonite at 10 and 5 mg/L concentrations.X-ray analysis suggests that the 2, 4, 6 trichloroaniline investigated is preferentially sorbed on mineral surface on kaolinite, while when sorption on montmorillonite is considered, a progressive swelling of the structure can be observed, due to sorption processes that also take place in the interlayer, as shown by the study carried out on the dehydrated Na-montmorillonite system.

 On the basis of percent adsorbed it can be concluded that test chemical 2, 4, 6- trichloroaniline has low sorption on clay standard kaolinite and Na-montmorillonite.

 

Another experimental study was reviwed from Environmental Science and Pollution Research journal (2006) in this study the sorption experiments were carried out by immersing 2.00 g of clay mineral namely kaolinite KGa-1 and montmorillonite in 100.0 mL of test chemical solutions at concentrations of 10.0, 50.0, 100.0 and 200.0 mg/L. Experiments with kaolinite KGa-1 were carried outat both pH 4.8 (the natural pH of kaolinite in water) and at pH 9.9 (to compare the sorption results with those of montmorillonite). The systems were electromagnetically stirred for at least 1 week and, at regular intervals, 500μLof the suspension were collected, centrifuged (4500 rpm, 6 minutes), filtered(0.45μm) and analysed by HPLC analysis to deduce the amount of test chemical retained.

For the desorption experiments, suspensions resulting from the sorption experiments were centrifuged (4500 rpm, 10 minutes), and the solid phase containing the sorbed test chemical was air-dried and then submerged in ultra pure water at the same solid/liquid ratio as in the sorption experiments (2.00 g/100.0 mL) The new system was stirred electromagnetically for 7 days and then 500μL of the suspension were collected, filtered and injected into the HPLC system for direct determination of the desorbed fraction.The substance 2, 4, 6-trichloronailine was strongly retained, with sorption of up to 8 mg/g, by the soil clays kaolinite KGa-1 and Na montmorillonite SWy-1. In desorption experiments, 2,4,6-trichloroaniline was the least desorbed from montmorillonite irreversibly retained on kaolinite.

 For sorption on kaolinite (KGa-1),equilibrium is achieved in less than four days 2, 4, 6-trichloroaniline is sorbed (from an initial concentration of 200.0 mg/L) at a rate of 7.3 mg per gram of mineral clay, comparable with that sorbed by montmorillonite. The desorption experiments carried out on the adsorbed kaolinite for the 2, 4, 6-trichloroaniline reveal no significant desorption, at least as detected by the HPLC method. This suggests that the test chemical and the clay mineral form irreversible interactions, capable of resisting the desorption strength of simulated leaching.

 

 

Last experimental study was reviewed from chemosphere journal (2008) in this study the sorption experiments are carried out in triplicate by putting in batch conditions 2.00 g of the sorbing material in 100.00 mL of test material aqueous solution at concentration 200.00 mg/L. The systems are electromagnetically stirred for a total time of 15 days, 1.00 mL of the surnatant is collected, centrifuged (4500 rpm, 6 min), filtered on 0.20 µm polypropylene membrane (VWR International, West Chester, PA, USA) and submitted to HPLC analysis for the determination of the amount of test chemical still present in solution. From the amount initially present the quantity retained is calculated and expressed as mg of test chemical retained in batch conditions by 1.00 g of sorbent material.

 To evaluate the amount of test chemical desorbed by the different leaching agents, the suspension obtained after 15 d of contact is centrifuged (4500 rpm, 10 min) and the solid phase (that contains the pollutant sorbed) is air-dried, weighed and submerged in the leaching solution in the same solid/liquid ratio as in the sorption experiments (2.00 g/100.00 mL). The new system is electromagnetically stirred for 15 d and then 1.00 mL of the supernatant is collected, filtered and injected into the HPLC system for the direct determination of the desorbed fraction of the test chemical. All the experiments are performed in triplicate.

 The test chemical 2,4,6-trichloroaniline adsorbed on clay Na-montmorrilonite(SWy-2) were 10.0 ± 0.6 and 3.1 ± 0.7 mg/g , on clay kaolinite (KGa-1b) 7.3 ± 0.9 and 5.5 ± 1.3 mg/g and on clay BCR_-700 10.0 ± 1.5 and 3.3 ± 0.4 mg/g of clay.

Further, the test chemical desorbed from all three types of clays was < 0.1 %.

Thus on the basis of adsorption values on all three types of clays it can be conclude that test chemical2,4,6-trichloroaniline shows capability to adsorb on different types of clays.

 

By considering results of all the studies mentioned above it can be concluded that test chemical 2,4,6-trichloroaniline(CAS No.634-93-5) shows moderate to low sorption to different types of clays and soil.

[LogKoc: 3.466]