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Adsorption / desorption

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Endpoint:
adsorption / desorption: screening
Type of information:
experimental study
Adequacy of study:
weight of evidence
Study period:
03 June 2010 - 31 August 2010
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: see 'Remark'
Remarks:
This study was conducted in accordance with international guidelines in a GLP testing laboratory. The study provided an indicative range of adsorption coefficients to be used for the purpose of defining values to be used in chemical safety assessment. Although the study could not be conducted at a pH where the components of the substance were not ionised, in accordance with ECHA Guidance on Information Requirements and Chemical Safety Assessment, the study was conducted at approximately neutral pH, which is relevant for environmental exposure assessment.
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:
HPLC estimation method
Radiolabelling:
no
Details on study design: HPLC method:
EQUIPMENT
- Apparatus: Agilent Tecnologies 1100 incorporating autosampler and workstation
- Type: HPLC
- Type, material and dimension of analytical (guard) column: Optimal CN 5micron (150 x 4.6 mm id)
- Detection system: UV (210nm for standards, 234nm for sample)

MOBILE PHASES
- Type: methanol:reverse osmosis water (55:45 v/v)
- Experiments with additives carried out on separate columns: no
- pH: 7.4
- Solutes for dissolving test and reference substances: test material dissolved in methanol:reverse osmosis water (55:45 v/v). Standards dissolved in methanol

DETERMINATION OF DEAD TIME
- Method: by inert substances (formamide purity >= 99.5%, 736mg/l solution in methanol:reverse osmosis water (55:45 v/v)) which are not retained by the column

DETERMINATION OF RETENTION TIMES
- Quantity of test substance introduced in the column: 10microlitres

REPETITIONS
- Number of determinations: 2
Analytical monitoring:
yes
Key result
Type:
log Koc
Value:
< 1.25 dimensionless
pH:
7.4
Remarks on result:
other: 20 % of the substance was found to be at this adsorption coefficient
Key result
Type:
log Koc
Value:
>= 1.25 - < 5.63 dimensionless
pH:
7.4
Remarks on result:
other: 50 % of the substance was found to be at this adsorption coefficient
Key result
Type:
log Koc
Value:
>= 5.63 dimensionless
pH:
7.4
Remarks on result:
other: 30 % of the substance was found to be at this adsorption coefficient
Details on results (HPLC method):
See results information in section below.

The retention times of formamide and the retention times, capacity factors (k) and log10 Koc values for the reference standards are shown in the following tables:

Standard Retention Time (mins) Mean Retention Time (mins)
Injection 1 Injection 2
Formamide 1.968 1.971 1.97

Standard Retention Time (mins) Mean Retention Time (mins) Capacity Factor (k) Log10 k Log10Koc
Injection 1 Injection 2
Acetanilide 2.53 2.53 2.527 0.283 -0.548 1.25
Phenol 2.60 2.60 2.602 0.321 -0.493 1.32
Atrazine 2.94 2.94 2.937 0.491 -0.309 1.81
Triadimenol 3.82 3.81 3.816 0.938 -2.8*10-2 2.4
Linuron 4.52 4.52 4.523 1.30 0.113 2.59
Naphthalene 4.19 4.19 4.191 1.13 5.22*10-2 2.75
Endosulfan-diol 5.60 5.60 5.601 1.84 0.266 3.02
Fenthion 6.71 6.71 6.712 2.41 0.382 3.31
α-Endosulfan 7.87 7.86 7.864 2.99 0.476 4.09
Phenanthrene 6.78 6.77 6.773 2.44 0.387 4.09
Diclofop-methyl 7.72 7.72 7.72 2.92 0.645 4.2
DDT 14.84 14.82 14.828 6.53 0.815 5.63

From the calibration curve:

A = -0.814

B = 0.311

r = 0.971

The retention times, capacity factors, log10 Koc and percentage area values determined for the sample are shown in the following table:

Peak Number(s) Injection Retention Time Range (mins) Capacity Factor (k) Log10k Log10 Koc Mean Log10 Koc Mean Area (%)
1 - 5 1 1.367 - 2.411 <0.283 <-0.548 <1.25 <1.25 20.4
2 1.366 - 2.322 <0.283 <-0.548 <1.25

6

1 2.903 0.474 -0.324 1.57 1.58 17.3
2 2.911 0.478 -0.321 1.59
7 1 3.133 0.591 -0.229 1.88 1.9 5.06
2 3.16 0.604 -0.219 1.91
8 - 22 1 4.165 - 14.745 1.12 - 6.49 4.71*10-2- 0.812 2.77 - 5.23 2.77 - 5.23 27.1
2 4.195 - 14.855 1.13 - 6.54 5.31*10-2- 0.816 2.79 - 5.24
23 - 28 1 16.448 - 28.952 >10.7 >1.03 >5.63 >5.63 30.2
2 16.560 - 29.100 >10.7 >1.03 >5.63

Mean log10 Koc: In the range <1.25 to >5.63

Adsorption coefficient: In the range <17.8 to >4.27*105

Validity criteria fulfilled:
yes
Conclusions:
The adsoroption coefficient of the test material has been determined to be in the range indicated below along with approximate percentage composition:
%age of Test Material Adsorption Coefficient
20 <1.25
50 1.25 to 5.63
30 >5.63
Executive summary:

The adsoroption coefficient of the test material (PR-4758) was measured in accordance with international guidelines in a GLP testing laboratory. The OECD guideline requires that substances are tested in their ionised and un-ionised form, however due to the dissociation properties of some of the components testing would need to have taken place at pH 11 which was experimentally impractical. The testing was hence carried out at neutral pH.

The adsoroption coefficient of the test material was determined to be in the range indicated below for approximate percentages of the substance composition:

%age of Test Material Adsorption Coefficient

20% = < 1.25

50% = 1.25 to 5.63

30% = > 5.63

Endpoint:
adsorption / desorption: screening
Type of information:
(Q)SAR
Adequacy of study:
weight of evidence
Reliability:
3 (not reliable)
Rationale for reliability incl. deficiencies:
other: see 'Remark'
Remarks:
As the substance is surface active (highly emulsifying), standard methods for the determination of adsorption/desorption coefficient were not suitable. The presented data were generated using the (Q)SAR KOCWIN as contibuting data towards a weight of evidence for this endpoint. Whilst this (Q)SAR does not have a strict domain of applicability, many of the constituents of this substance had a molecular weight outside the range of the training set. Additionally, this (Q)SAR is not suitable for surface active substances, so the results need to be trated with caution. This study is, however, deemed suitable for use in a weight-of-evidence approach to reach a conclusion on the adsorption/desorption properties of this substance.
Justification for type of information:
QSAR prediction: migrated from IUCLID 5.6
Guideline:
other: ECHA Guidance on Information Requirements and Chemical Safety Assessmnet, Chapter R.6: QSARs and Grouping of Chemicals. May 2008.
Principles of method if other than guideline:
KOCWIN, version 2.00, © 2000-2008 US Environmental Protection Agency.
GLP compliance:
no
Type:
log Koc
Value:
0.4
Temp.:
25 °C
Remarks on result:
other: COMPONENT B
Type:
log Koc
Value:
0.09
Temp.:
25 °C
Remarks on result:
other: COMPONENT D
Type:
log Koc
Value:
2.25
Temp.:
25 °C
Remarks on result:
other: COMPONENT F
Type:
log Koc
Value:
9.18
Temp.:
25 °C
Remarks on result:
other: COMPONENT H
Type:
log Koc
Value:
7.49
Temp.:
25 °C
Remarks on result:
other: COMPONENT I
Type:
log Koc
Value:
7.41
Temp.:
25 °C
Remarks on result:
other: COMPONENT J

Refer to attached (Q)PRF.

Conclusions:
The predictions presented for fatty acids, C18 unsaturated, reaction products with diethylenetriamine, Acrylic acid and ethylene glycol monobutyl ether are only suitable as supporting information for the organic carbon partition coefficient endpoint.
Executive summary:

This prediction was performed to support the Adsorption coefficient endpoint which is being submitted under Regulation (EC) No 1907/2006 (REACH) using the (Q)SAR KOCWIN.

The substance is composed of a number of C18 unsaturated reaction product molecules with a molecular weight range of 611 – 732 g/mol. Although there is no formally defined domain of applicability for this (Q)SAR, the majority of components of the substance predicted fall outside the molecular weight range of the training set, which may cast doubt on the adequacy of the prediction.

The substance is also considered to be surface active, which renders the adequacy of the prediction as “inadequate”. This (Q)SAR is not suitable for surface active substances.

The predictions presented for fatty acids, C18 unsaturated, reaction products with diethylenetriamine, Acrylic acid and ethylene monobutyl ether are only suitable as supporting information for the organic carbon partition coefficient endpoint.

Description of key information

Butler & White (2010): log Koc = < 0.3 - > 6.5 (OECD 121)

Walker (2014): log Koc = 0.4 - 9.2 (KOCWIN)

Key value for chemical safety assessment

Koc at 20 °C:
10 000

Additional information

Butler & White (2010) concluded that the substance has an estimated range of adsorption coefficients ranging from log Koc = 0.3 - 5.6 when using the OECD 121 HPLC screening method, indicating a wide range of adsorption characteristics for the substance. Similarly, the supporting study by Walker (2014) concluded that the substance has an estimated range of adsorption coefficients ranging from log Koc = 0.4 - 9.2 when using the (Q)SAR KOCWIN.

As the substance has no specified value for adsorption coefficients, a maximum modelling value of 10,000 L/kg was used. This value is the maximum value that will result in worst-case partitioning in environmental exposure models. The hydrocarbon structures of this mixture are consistent with highly cationic surfactants, which upon entering the aquatic environmental compartment will quickly form complexes with dissolved organics, particularly with anionic compounds, and are strongly adsorbed onto solids. The theory behind this approach is to compensate for the uncertainty associated with water solubility, Kow and Koc values by ensuring that worst-case exposure values will be estimated for pelagic and benthic compartments during environmental exposure modelling.

[LogKoc: 4.0]

[LogKoc: 4.0]