Registration Dossier

Administrative data

Endpoint:
adsorption / desorption
Remarks:
other: adsorption/desorption screening test
Type of information:
experimental study
Adequacy of study:
key study
Study period:
8th June 2006
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study

Data source

Reference
Reference Type:
other: Body responsible for the test
Title:
Unnamed
Year:
2006
Report date:
2006

Materials and methods

Test guideline
Qualifier:
according to guideline
Guideline:
other: Official Journal of the European Communities, L225, Part C19, Estimation of the adsorption coefficient (Koc)on soil and sewage sludge using HPLC. 21 August 2001
GLP compliance:
yes
Media:
soil

Test material

Constituent 1
Test material form:
solid: particulate/powder
Details on test material:
Light pink tinted powder
Specific details on test material used for the study:
The test substance was recieved at Brixham Environmental Laboratory on 20 Feb 2006 and assigned the Brixham test substance number 06-0037. The test substance (ref Y12511/002/001, bottle no 287981) was supplied as a lightly pink tinted powder. A certificate of analysis (Report Ref 1302034, ASG Ref No 10379810, dated 8 May 2006) state the sample had a purity of 99.8% w/w,

the sample was stored at ambient temperature, in the container in which it was recieved, until required for testing, when an appropriate subsample was provided for the test operator.

Study design

Test temperature:
ca 21 °C

HPLC method

Details on study design: HPLC method:
A HPLC system comprising the following components was set up:

HPLC pump
Injection valve filled with 100 µl loop
25 cm x 4.6 mm id column packed with a 5 µm CN phase
Photo Diode Array (PDA) detector extracted at 215 nm and 240 nm
Chromatography data system

Batch equilibrium or other method

Analytical monitoring:
yes
Details on test conditions:
HPLC is performed on analytical columns packed with a commercially available solid phase containing lipophilic and polar moieties. For the purposes of this technique a moderaly polar stationary phase based on a silica matrix is used:

-O-Si - CH2-CH2-CH2 - CN
Silica apolar spacer Polar moiety

chemicals injected onto such a column move along it by partioning between the mobile phase and the stationary phase. The velocity of each component thereby depends on the degree of adsorption to a stationary phase, which exhibits non-polar as well as polar activity.

This allows for interaction of non-polar and polar parts of a molecule in a similar way as is the case for soil components. This enables the relationship between the retention time on such a column and the adsorption coefficient on the organic part of a soil to be established.

In order to correlated the measured HPLC retention time of a test substance with its adsorption coefficient it is necessary to determine the retention time of a range of reference substances with known adsorption coefficient values. Using the column dead time (from the "retention time" of an inert substance) and the retention data of the reference substances, the k' values are calculated and a calibration graph of log10Koc versus log10k' is established. Using the equation of this line the log10k' result from the test substance is used to estimate its log10Koc value.

Since only the relationship between the retention on the HPLC column and the adsorption coefficient is employed for this evaluation, no quantitative analysis is required and only the determination of the retention time is necessary.

Results and discussion

Adsorption coefficient
Type:
Koc
Value:
ca. 2.2 dimensionless

Results: HPLC method

Details on results (HPLC method):
The retention times from the individual injections and the derived k' values are given in Table 1. Individual retention times were within 15% of each other. A typical chromatogram is shown in Appendix 1.

From the experimentally derived k' measurements and the literature KOCvalues of the reference substance (Ref 1), the equation of the fitted regression line was determined as log10KOC = a.log10k'+b

Where a=11.317
b= 2.859

This data is displayed graphically in figure 1. the coefficient of determination (r2) of these data was calculated as 0.963 indicating an approximate linear relationship between log10KOC and log10k'.

The log10k' for UL125 was -0.0577 and -0.0590 for the 25 mg/l and 50 mg/l concentrations respectively. Therefore, from the above equation, the estimated log10KOC for UL125 was 2.20.

The test described has been validated for the quantitative estimation of log10KoC values in the range 1.5 to 5.0

Results: Batch equilibrium or other method

Transformation products:
no

Any other information on results incl. tables

Substance

Retention time injection 1 (s)

Retention time injection 2 (s)

Mean retention time, tr(s)

Derived k’ value

(a)

log10k’

Log10KOC

Sodium Nitrate

78

78

78 b

-

-

-

Acetanilide

130

130

130

0.667

-0.176

1.25 c

Atrazine

140

140

140

0.795

-0.100

1.81 c

Isoproturon

147

148

148

0.897

-0.047

1.86 c

Linuron

151

151

151

0.936

-0.029

2.59 c

Napthalene

159

159

159

1.038

0.016

2.75 c

1,2,3- Trichlorobenzene

162

162

162

1.077

0.032

3.16 c

Fenthion

165

165

165

1.115

0.047

3.31 c

Phenanthrene

172

172

172

1.205

0.081

4.09 c

ppDDT

211

211

211

1.705

0.232

5.63 c

UL125 (25 mg/l)

146

146

146

0.872

-0.060

2.20

UL125 (50 mg/l)

146

146

146

0.872

-0.060

2.20

a: k'=(tr-t0)/t0

b: this is the t0 value used in the calculation of k'

c: Soil log10KOC literature value

Applicant's summary and conclusion

Validity criteria fulfilled:
yes