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Reference
Endpoint:
adsorption / desorption: screening
Type of information:
experimental study
Adequacy of study:
key study
Study period:
From 7 June, 2012 to 18 Oct, 2012
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to
Guideline:
EU Method C.19 (Estimation of the Adsorption Coefficient (KOC) on Soil and Sewage Sludge Using High Performance Liquid Chromatography (HPLC))
Version / remarks:
(2008)
Deviations:
no
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))
Version / remarks:
(2001)
Deviations:
no
GLP compliance:
yes
Type of method:
HPLC estimation method
Media:
soil/sewage sludge
Radiolabelling:
no
Details on study design: HPLC method:
CALCULATION OF PKA
The following pKa values in the pH range of 1-14 were calculated using the Perrin calculation method (pKalc 5.0, module in Pallas 3.0, CompuDrug International San Francisco, USA): pKa acidic: none; pKa basic: none.

HPLC METHOD CONDITIONS
Based on the pKa calculations, the mobile phase was not buffered.

Instrument: Alliance Separation Module 2695 (Waters, USA)
Detector: Dual λ Absorbance Detector 2487 (Waters)
Column: Hypersil-BDS-CN, 150 mm x 4.6 mm i.d., dp= 5 µm (Thermo Fisher Scientific, USA)
Column temperature: 35°C ± 1°C
Mobile phase: 55/45 (v/v) methanol/water
Flow: 1 mL/min
Injection volume: 10 µL
UV detection: 210 nm

REFERENCE SUBSTANCES
Log Koc values based on soil adsorption data (OECD 121):
-Acetanilide, > 99.9%, CAS 103-84-4, log Koc 1.26
-Atrazine, 97.5%, CAS 1912-24-9, log Koc 1.81
-Monuron, 99.9%, CAS 150-68-5, log Koc 1.99
-2,5-Dichloroaniline, 99.8%, CAS 95-82-9, log Koc 2.55
-Benzoic acid phenylester, 99.9%, CAS 93-99-2, log Koc 2.87
-Fenthion, 96.2%, CAS 55-38-9, log Koc 3.31
-Phenanthrene, 98.1%, CAS 85-01-8, log Koc 4.09
-4,4’-DDT, 98.2%, CAS 50-29-3, log Koc 5.63

PREPARATION OF SOLUTIONS
Stock solutions of the reference substances at concentrations of approximately 1 g/L in methanol were used. The stock solutions were diluted to obtain an end solution of 55/45 (v/v) methanol/water. A 1104 mg/L stock solution of the test substance was prepared in methanol. The stock solution was diluted to obtain a final concentration of 121 mg/L. End solution: 55/45 (v/v) methanol/water. All solutions containing the test substance were protected from light. A 5.61 g/L stock solution of the unretained compound formamide (99.8%) in methanol was used. The stock solution was diluted to obtain an end solution of 55/45 (v/v) methanol/water.

PERFORMANCE OF THE STUDY
The reference substance and test substance solutions were injected in duplicate. Blank solution (55/45 (v/v) methanol/water) was analysed by single injection. The capacity factor (k') of each compound was calculated from its retention time. The log k’ values of the references substances were plotted against the known log Koc values. A linear regression program was used to calculate the calibration curve (least squares method). The log Koc value for the test substance was calculated by substituting its mean log k’ in the calibration curve: log k’ = 0.2864 x log Koc– 1.095 (r=0.974, n=16).
Key result
Type:
log Koc
Value:
ca. 3.61 dimensionless
Remarks on result:
other: Peak area: 66%. Koc= 4,000
Key result
Type:
log Koc
Value:
ca. 1.26 - ca. 5.63 dimensionless
Remarks on result:
other: Peak area: 0.02 to 11%; Koc < 18 to > 4.3E+5
Details on results (HPLC method):
In the HPLC chromatograms of the test substance solution, one major peak and several small test substance peaks were observed. Measurements and results are summarized in the table below.

Chromatogram and calibration curve: see attachment.


Table 1: Measurements and results for the Koc determination

Substance

tr,1
[min]

tr,2
[min]

mean tr
(n=2)

log Koc

Koc

Area
%

Formamide (t0)

1.964

1.963

1.964

 

  

 

Acetanilide

2.247

2.249

  

1.26

 

 

Atrazine

2.455

2.455

 

1.81

 

 

Monuron

2.531

2.531

 

1.99

 

 

2,5-Dichloroaniline

2.856

2.857

 

2.55

 

 

Benzoic acid

phenylester

3.130

3.132

 

2.87

 

 

Fenthion

4.144

4.146

 

3.31

 

 

Phenantrene

4.146

4.149

 

4.09

 

 

4,4'-DDT

7.215

7.218

 

5.63

 

 

  

  

 

 

 

 

 

Peak 1

0.822

0.832

0.827

< 1.26

<1.8 E1

0.3

Peak 2

1.262

1.258

1.260

< 1.26

<1.8 E1

0.3

Peak 3

1.977

1.985

1.981

< 1.26

<1.8 E1

0.5

Peak 4

2.242

2.243

2.243

< 1.26

<1.8 E1

0.1

Peak 5

2.522

2.530

2.526

1.93

8.4 E1

0.1

Peak 6

2.663

2.661

2.662

2.26

1.8 E2

0.2

Peak 7

2.944

2.945

2.945

2.77

5.9 E2

4.7

Peak 8

3.075

3.076

3.076

2.96

9.1 E2

0.7

Peak 9

3.193

3.193

3.193

3.11

1.3 E3

0.3

Peak 10

3.435

3.436

3.436

3.39

2.4 E3

0.3

Peak 11 (Major

compound)

3.664

3.664

3.664

3.61

4.0 E3

66

Peak 12

3.888

3.889

3.889

3.79

6.2 E3

8.3

Peak 13

4.149

4.151

4.150

3.99

9.7 E3

0.8

Peak 14

4.420

4.433

4.427

4.17

1.5 E4

0.1

Peak 15

4.919

4.916

4.918

4.44

2.8 E4

0.1

Peak 16

5.217

5.215

5.216

4.59

3.9 E4

0.1

Peak 17

5.775

5.773

5.774

4.83

6.7 E4

0.5

Peak 18

6.192

6.201

6.197

4.99

9.7 E4

0.02

Peak 19

6.671

6.669

6.670

5.15

1.4 E5

1.6

Peak 20

7.180

7.183

7.182

5.31

2.0 E5

0.4

Peak 21

7.907

7.894

7.901

> 5.63

> 4.3E5

0.2

Peak 22

8.706

8.728

8.717

> 5.63

> 4.3E5

0.03

Peak 23

9.682

9.678

9.680

> 5.63

> 4.3E5

11

Peak 24

10.450

10.459

10.455

> 5.63

> 4.3E5

3.3

 

 

Validity criteria fulfilled:
not specified
Conclusions:
Using the HPLC method at neutral pH and using soil-adsorption-reference data, the log Koc of di-TMPTTA for the major component was determined to be 3.61. The minor components had log Koc values between < 1.26 and > 5.63.
Executive summary:

The HPLC method at neutral pH using soil-adsorption reference data was applied for the determination of the adsorption coefficient of di-TMPTTA in accordance with OECD Guideline 121 and EU Method C.9. The mobile phase was 55/45 (v/v) methanol/water. The column temperature was 35°C. In the HPLC chromatogram, one major peak (66% peak area) and 23 smaller peaks (0.02 - 11% peak area) were observed. The log Koc value for the major component was 3.61 (Koc: 4,000). The log Koc values for the minor components ranged from < 1.26 to > 5.63 (Koc from < 18 to > 4.3E+5) (Lammers 2013).

Description of key information

Using the HPLC method at neutral pH and soil-adsorption-reference data, the log Koc of di-TMPTTA for the major component was determined to be 3.61. The minor components had log Koc values between < 1.26 and > 5.63.

Key value for chemical safety assessment

Koc at 20 °C:
4 000

Additional information

The HPLC method at neutral pH using soil-adsorption reference data was applied for the determination of the adsorption coefficient of di-TMPTTA in accordance with OECD Guideline 121 and EU Method C.9. The mobile phase was 55/45 (v/v) methanol/water. The column temperature was 35°C. In the HPLC chromatogram, one major peak (66% peak area) and 23 smaller peaks (0.02 - 11% peak area) were observed. The log Koc value for the major component was 3.61 (Koc: 4,000). The log Koc values for the minor components ranged from < 1.26 to > 5.63 (Koc from < 18 to > 4.3E+5) (Lammers 2013).

[LogKoc: 3.61]