C-M5

Adsorption / desorption

Administrative data

Endpoint:

adsorption / desorption: screening

Type of information:

experimental study

Adequacy of study:

key study

Study period:

Testing was conducted between 28 March 2007 and 24 April 2007.

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: 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 no effect the quality of the relevant results

Cross-reference

Reason / purpose for cross-reference:

reference to other study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2007

Report date:

2007

Materials and methods

Test guideline

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

Principles of method if other than guideline:

Screening method

GLP compliance:

yes (incl. QA statement)

Remarks:

UK GLP standards (Schedule 1, Good Laboratory Practice Regulations 1999 (SI 1999/3106 as amended by SI 2004/0994)).

Type of method:

HPLC estimation method

Media:

other: Not applicable.

Test material

Reference

Name:

Unnamed

Type:

Constituent

Test material form:

solid: particulate/powder

Remarks:

migrated information: powder

Radiolabelling:

no

Study design

Test temperature:

40ºC

HPLC method

Details on study design: HPLC method:

Preparation of sample solution:
Test material (0.0260 g) was diluted to 100 ml with glass double-distilled water.

Preparation of reference solutions:
The dead time was determined by measuring the retention time of formamide (purity* 99.5%, 533 mg/l solution in mobile phase).

Solutions of reference standards (see table 8.1) were prepared in methanol.

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

HPLC System: Agilent Technologies 1100, incorporating autosampler and workstation
Column: Zorbax SB-CN (250 x 4.6 mm id)
Column temperature: 40ºC
Mobile phase: 55:45 methanol:reverse osmosis water
pH of mobile phase: 7.0
Flow-rate: 1 ml/min
UV detector wavelength: dead time and reference standards: 210 nm, sample: 510 nm
Injection volume: 10 µl

Construction of calibration curve:
A calibration curve was constructed from the retention time data of the formamide and reference standard solutions. The capacity factors (k) for the reference standards were calculated using Equation 8.1 (see below)

Adsorption coefficient of sample:
The capacity factor was calculated using Equation 8.1 (see below) and the log10 Koc value determined with reference to the calibration curve.


Calculation
The capacity factor was determined using Equation 8.1 (please see below).

Batch equilibrium or other method

Analytical monitoring:

no

Details on sampling:

Not applicable.

Details on matrix:

Not applicable.

Details on test conditions:

Not applicable.

Computational methods:

Not applicable.

Results and discussion

Adsorption coefficient

Adsorption coefficient 1

Type:

Koc

Value:

< 17.8

Adsorption coefficient 2

Type:

log Koc

Value:

< 1.25

Results: HPLC method

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 tables 8.2 and 8.3 (please see remarks section).

Results: Batch equilibrium or other method

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.

Transformation products:

not measured

Details on results (Batch equilibrium method):

Not applicable.

Statistics:

None stated.

Any other information on results incl. tables

Table 8.2

Dead Time	Retention Time (mins)		Mean Retention Time (mins)
	Injection 1	Injection 2
Formamide	2.852	2.851	2.852

Table 8.3

Standard	Retention Time (mins)		Mean Retention Time (mins)	Capacity Factor (k)	Log10k	Log10Koc
	Injection 1	Injection 2
Acetanilide	3.772	3.775	3.774	0.323	-0.490	1.25
Phenol	3.609	3.574	3.592	0.260	-0.586	1.32
Atrazine	5.174	5.176	5.175	0.815	-8.89 x 10^-2	1.81
Isoproturon	5.417	5.418	5.418	0.900	-4.58 x 10^-2	1.86
Triadimenol	6.909	6.909	6.909	1.42	0.153	2.40
Linuron	10.539	10.533	10.536	2.70	0.431	2.59
Naphthalene	6.352	6.353	6.353	1.23	8.91 x 10^-2	2.75
Endosulfan-diol	8.303	8.318	8.311	1.91	0.282	3.02
Fenthion	10.579	10.577	10.578	2.71	0.433	3.31
a-Endosulfan	14.548	14.545	14.547	4.10	0.613	4.09
Phenanthrene	12.246	12.246	12.246	3.30	0.518	4.09
Diclofop-methyl	16.166	16.165	16.166	4.67	0.669	4.20
DDT	31.059	31.187	31.123	9.92	0.996	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 8.4

Injection	Retention Time (mins)	Capacity Factor (k)	Log10k	Log10Koc
1	1.691	-0.407	< -0.490	<1.25
2	1.692	-0.407	< -0.490	<1.25

Mean log₁₀K_oc:                       <1.25
Adsorption coefficient: <17.8

Discussion

The low adsorption properties of the test material containing salted sulfonic acid functional groups determined by the HPLC estimation method were consistent with the extremely high water solubility and low partition coefficient characteristics (see Safepharm Laboratories Ltd Project Number 0345/0889). Although the determined value is believed to accurately assess the affinity of the test material for the organic carbon content of soils and sewage sludge (the method guideline specifically requiring the analysis of substances in an ionised form if present within the environmentally relevant pH range of 5.5 to 7.5), the mobility of the test material in soil and sewage sludge may also be influenced by additional interactions other than partitioning not addressed by the test method due to the anionic nature of the test material.

The alternative use of computer-based estimation programs and/or Quantitative Structure Activity Relationships (QSAR’s) for materials of this nature are considered invalid as estimates are typically derived from the partition coefficient value. Therefore once more the possible secondary interaction originating from the anionic charges present on the test material are not addressed.

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Conclusions:

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

Executive summary:

Adsorption Coefficient. 

<17.8, log₁₀K_oc <1.25, using the HPLC screening method, Method C19 of Commission Directive 2001/59/EC, Method 121 of the OECD Guidelines for Testing of Chemicals, 22 January 2001.