3-[3-(1,1,1,3,5,5,5-heptamethyltrisiloxan-3-yl)propoxy]- 2-hydroxypropyl methacrylate and 1-[3-(1,1,1,3,5,5,5-heptamethyltrisiloxan-3-yl)propoxy]-3-hydroxypropan-2-yl methacrylate

Adsorption / desorption

Link to relevant study record(s)

Reference

Endpoint:

adsorption / desorption: screening

Type of information:

experimental study

Adequacy of study:

key study

Study period:

Testing was conducted between 16 June 2008 and 18 June 2008.

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Study conducted in compliance with agreed protocols, with no or minor deviations from standard test guidelines and/or minor methodological deficiencies, which do not affect the quality of the relevant results.

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

Media:

other: Test material diluted with methanol.

Radiolabelling:

no

Test temperature:

Column temperature: 30ºC

Details on study design: HPLC method:

Procedure

Preparation of sample solution:
Test material (0.0107 g) was diluted to 10 ml with methanol.

Preparation of dead time solution:
The dead time was determined by measuring the retention time of formamide (purity>99.5%, 1.14 x 10E3 mg/l solution in mobile phase).

Preparation of reference standard solutions:
Solutions of reference standards (see following table) were prepared in methanol.

Standard Purity (%) Concentration (mg/l)
Acetanilide 99+ 119
Phenol 99+ 109
Isoproturon 99.8 103
Triadimenol 98.4 120
Linuron 99 102
Naphthalene ≥99 114
Endosulfan-diol 99.8 105
Fenthion 99 171
α-Endosulfan 99.6 111
Phenanthrene ≥97.0 105
Diclofop-methyl 99.5 109
DDT 98 102

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 1100, incorporating autosampler and workstation
Column: Phenosphere NEXT 5µ CN (250 x 4.6 mm id)
Column: 30ºC
Mobile phase: methanol:reverse osmosis water (55:45 v/v)*
pH of mobile phase: 6.8
Flow-rate: 1.0 ml/min
Injection volume: 10 µl
UV detector wavelength: 210 nm

* a gradient elution comprising of a change of the mobile phase to 100% methanol after the retention time of DDT was utilised to elute the highly retained test material remaining on the HPLC column. This was performed on the sample and sample blank injections only.

Construction of calibration curve:
A calibration curve was constructed from the retention time data of the deadtime and reference standard solutions (Figure 5.1 - please see attached background material). The capacity factors (k) for the reference standards were calculated using Equation 5.1 (please see information on materials and methods section).

Adsorption coefficient of sample:
The capacity factor was calculated using Equation 5.1 and the log10Koc value determined using Equation 5.2 (please see information on materials and methods section) with reference to the calibration curve (Figure 5.1).

Analytical monitoring:

no

Details on sampling:

Not applicable.

Details on matrix:

Not applicable.

Details on test conditions:

Not applicable.

Computational methods:

Not applicable.

Type:

Koc

Value:

> 427 000 dimensionless

pH:

6.8

Temp.:

30 °C

Type:

log Koc

Value:

> 5.63 dimensionless

pH:

6.8

Temp.:

30 °C

Details on results (HPLC method):

Calibration:
The retention times of formamide and the retention times, capacity factors (k) and log10 Koc values for the reference standards are shown in the two following tables (Table 5.1 and 5.2 - please see remarks on results including tables and figures section).

Adsorption coefficient of sample:
The retention times, capacity factors and log10 Koc values determined for the sample are shown in the following table (Table 5.3 - please see remarks on results including tables and figures section).

Adsorption and desorption constants:

Not applicable.

Recovery of test material:

Not applicable.

Concentration of test substance at end of adsorption equilibration period:

Not applicable.

Concentration of test substance at end of desorption equilibration period:

Not applicable.

Details on results (Batch equilibrium method):

Not applicable.

Statistics:

None stated.

Calibration

The retention times of formamide and the retention times, capacity factors (k) and log₁₀K_ocvalues for the reference standards are shown in the two following tables:

Table 5.1

Dead Time	Retention Time (mins)		Mean Retention Time (mins)
	Injection 1	Injection 2
Formamide	3.252	3.251	3.252

Table 5.2

Standard	Retention Time (mins)		Mean Retention Time (mins)	Capacity Factor (k)	Log10k	Log10Koc
	Injection 1	Injection 2
Acetanilide	4.011	4.009	4.010	0.233	-0.632	1.25
Phenol	4.051	4.051	4.051	0.246	-0.609	1.32
Isoproturon	4.931	4.928	4.930	0.516	-0.287	1.86
Triadimenol	5.209	5.208	5.209	0.602	-0.220	2.40
Linuron	6.243	6.234	6.239	0.919	-3.69 x 10^-2	2.59
Naphthalene	8.211	8.195	8.203	1.52	0.183	2.75
Endosulfan-diol	6.086	6.080	6.083	0.871	-6.01 x 10^-2	3.02
Fenthion	10.554	10.544	10.549	2.24	0.351	3.31
a-Endosulfan	10.667	10.629	10.648	2.28	0.357	4.09
Phenanthrene	14.543	13.269	13.906	3.28	0.515	4.09
Diclofop-methyl	12.953	12.860	12.907	2.97	0.473	4.20
DDT	25.901	25.847	25.874	6.96	0.842	5.63

Adsorption coefficient of sample

The retention times, capacity factors and log₁₀K_ocvalues determined for the sample are shown in the following table:

Table 5.3

Injection	Retention Time (mins)	Capacity Factor (k)	Log10k	Log10Koc
1	75.052	>6.96	>0.842	>5.63
2	75.042	>6.96	>0.842	>5.63

Mean log₁₀K_oc:                       >5.63
Adsorption coefficient: >4.27 x 10⁵

Discussion

The method guideline states that the measurement of adsorption coefficient should be carried out on substances in their ionised and unionised forms. However, the dissociation constants of certain functional groups found in the test material made it impossible to satisfy this criterion. Testing would be required at an extremely high pH to fully ionise the alcoholic functional groups. Therefore, as an excessively high pH is outside the environmental pH range for this test (and also experimentally impractical), testing was carried out at approximately neutral pH with the test material in its unionised form

Validity criteria fulfilled:

yes

Conclusions:

The adsorption coefficient (Koc) of the test material has been determined to be greater than log10 Koc >5.63.

Executive summary:

Method

The determination was carried out using the HPLC screening method, Method C19 of Commission Directive 2001/59/EC.

Conclusion

The adsorption coefficient (K_oc) of the test material has been determined to be greater than 4.27 x 10⁵, log₁₀ K_oc >5.63.

Description of key information

To assess adsorption/desorption properties of the substance (SiMAA2), an experimental result has been read-across from a structural analogue substance (EC 700-043-1)

The determination was carried out using the HPLC screening method, Method C19 of Commission Directive 2001/59/EC.

The adsorption coefficient (K_oc) of the test material (strucutral analogue) has been determined to be greater than 4.27 x 10⁵, log₁₀K_oc >5.63.

Key value for chemical safety assessment

Koc at 20 °C:

427 000

Additional information

[LogKoc: 5.63]