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Environmental fate & pathways

Adsorption / desorption

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Reference
Endpoint:
adsorption / desorption: screening
Type of information:
experimental study
Adequacy of study:
key study
Study period:
Between 17 May 2012 and 03 July 2012.
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Remarks:
Study conducted to GLP and in compliance with agreed protocols, with no or minor deviations from standard test guidelines and/or minor methodological deficiencies, which do not effect the quality of the relevant results.
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))
Deviations:
no
Qualifier:
according to guideline
Guideline:
EU Method C.19 (Estimation of the Adsorption Coefficient (KOC) on Soil and Sewage Sludge Using High Performance Liquid Chromatography (HPLC))
Deviations:
no
GLP compliance:
yes (incl. QA statement)
Type of method:
other: HPLC screening method
Media:
other: test item and reference standards prepared in methanol
Radiolabelling:
no
Test temperature:
30ºC (column temperature)
Details on study design: HPLC method:
Performance of the Test:
Preparation of sample solution:
Test item (0.1027 g) was diluted to 100 mL with methanol. This solution was further diluted by a factor of 10 using methanol to give a concentration of 0.103 g/L.

Preparation of dead time solution:
The dead time was determined by measuring the retention time of formamide (purity 99.94%) at 615 mg/L solution in mobile phase.

Preparation of reference standard solutions:
Solutions of reference standards (see table 3.27 within the any other information on materials and methods incl. tables section below) were prepared in methanol.

Determination of retention time:
The sample, dead time and reference standard solutions were injected in duplicate using the following HPLC parameters:

HPLC System: Agilent Technologies 1050 incorporating autosampler and workstation
Column: Xselect HSS cyano 5 µ (150 x 4.6 mm id)
Column temperature: 30ºC
Mobile phase: Methanol:water (55:45 v/v)
pH of mobile phase: 7.0 adjusted with 0.1 M sodium hydroxide
Flow-rate: 1.0 mL/min
Injection volume: 5 µL
UV detector wavelength : 210 nm














Type:
Koc
Value:
< 17.8
Temp.:
30 °C
Type:
log Koc
Value:
< 1.25
Temp.:
30 °C
Details on results (HPLC method):
Please see below.

Calibration

The retention times of the dead time and the retention times, capacity factors (k') and log10Kocvalues for the reference standards are shown in the two following tables:

 

Table 3.29

 

Dead Time

Retention Time (mins)

Mean Retention Time (mins)

Injection 1

Injection 2

Formamide

2.043

2.043

2.043

Table 3.30

 

Standard

Retention Time (mins)

Mean Retention Time (mins)

Capacity Factor (k')

Log10 k'

Log10 Koc

Injection 1

Injection 2

Acetanilide

2.847

2.847

2.847

0.393

-0.405

1.25

Phenol

2.733

2.733

2.733

0.338

-0.471

1.32

Atrazine

3.980

3.980

3.980

0.948

-2.32 x 10-2

1.81

Isoproturon

4.337

4.343

4.340

1.124

5.08 x 10-2

1.86

Triadimenol

6.127

6.110

6.118

1.994

0.300

2.40

Linuron

6.347

6.357

6.352

2.108

0.324

2.59

Naphthalene

5.383

5.370

5.377

1.631

0.213

2.75

Endosulfan-diol

8.263

8.233

8.248

3.037

0.482

3.02

Fenthion

9.900

9.833

9.867

3.829

0.583

3.31

Diclofop-methyl

15.483

15.443

15.463

6.568

0.817

4.20

Phenanthrene

10.570

10.517

10.543

4.16

0.619

4.09

DDT

31.770

31.640

31.705

14.516

1.162

5.63

Adsorption coefficient of sample

The retention times, capacity factor and log10Kocvalue determined for the sample are shown in the following table:

 

Table 3.31

 

Injection

Retention Time (mins)

Capacity Factor (k')

Log10k'

Log10Koc

Adsorption Coefficient

1

2.593

<0.393

<-0.405

<1.25

<17.8

2

2.590

<0.393

<-0.405

<1.25

<17.8

 

Overall log10Koc:                    <1.25

Adsorption coefficient:           <17.8

Validity criteria fulfilled:
yes
Conclusions:
The adsorption coefficient of the test item has been determined to be <17.8, log10 Koc <1.25. This value indicates that the test item has very high environmental mobility.
Executive summary:
Method The determination was carried out using the HPLC screening method, designed to be compatible with Method 121 of the OECD Guidelines for Testing of Chemicals, 22 January 2001 and Method C19 Adsorption Coefficient of Commission Regulation (EC) No 440/2008 of 30 May 2008.

 

The test utilized a high performance liquid chromatograph. A commercially available cyanopropyl reverse phase HPLC column containing lipophilic and polar moieties was used.

         

Discussion

The mobile phase was adjusted to pH 7 to ensure the partition coefficient was determined at a neutral pH. The test item had no dissociation constants within the environmentally relevant pH range.

 

As the slope of the calibration curve for the reference standards showed good first order correlation and as the retention times between duplicate injections for each solution was consistent, the HPLC method was considered valid for the determination of adsorption coefficient. Based on the chromatographic data, the test item was considered to be stable during the test procedure.

   

Conclusion

The adsorption coefficient of the test item has been determined to be <17.8, log10Koc <1.25. This value indicates that the test item has very high environmental mobility.

Description of key information

The adsorption coefficient of the test item has been determined to be <17.8, log10 Koc <1.25. 

Key value for chemical safety assessment

Koc at 20 °C:
17.8

Additional information

The determination was carried out using the HPLC screening method, designed to be compatible with Method 121 of the OECD Guidelines for Testing of Chemicals, 22 January 2001 and Method C19 Adsorption Coefficient of Commission Regulation (EC) No 440/2008 of 30 May 2008. The test utilized a high performance liquid chromatograph.

The mobile phase was adjusted to pH 7 to ensure the partition coefficient was determined at a neutral pH. The test item had no dissociation constants within the environmentally relevant pH range.

The adsorption coefficient of the test item has been determined to be <17.8, log10 Koc <1.25.  This value indicates that the test item has very high environmental mobility.

[LogKoc: 1.25]