Registration Dossier

Administrative data

Endpoint:
adsorption / desorption: screening
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: Meets the criteria for classification as Reliable without restriction according to Klimisch et al (1997)

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2004

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
OECD Guideline 121 (Estimation of the Adsorption Coefficient (Koc) on Soil and on Sewage Sludge using High Performance Liquid Chromatography (HPLC))
GLP compliance:
yes
Type of method:
HPLC estimation method
Media:
other: HPLC Method using analytical columns packed with a commercially available solid phase containing lipophilic and polar moieties.

Test material

Reference
Name:
Unnamed
Type:
Constituent
Radiolabelling:
no

Study design

Test temperature:
The temperature of the room in which the study was carried out was recorded throughout the test at hourly intervals using a Kane & May KM1241 thermocouple/data logging temperature recording system. The temperature of the room in which the HPLC work was done ranged between 21.5
and 23.3°C.

HPLC method

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

HPLC pump

25 cm x 4.6 mm id column packed with a 5 u/l CN phase

Photo Diode Array (PDA) detector

Chromatography data system

The injection volume was 100 ul.

Mobile phase
The standard mobile phase consisted of 55% methanol and 45% pH adjusted deionised water. Mobile phase was pumped through at a flow rate of 1.5 ml min-1
.
Test procedure

Determination of column dead time
The solution of sodium nitrate was injected in duplicate to determine to column dead time..

Determination of retention times
All the reference substances were injected in duplicate, as a minimum, and the mean retention times were determined. This was performed at least once daily so that possible changes in column performance could be allowed for.
Two concentrations, 10 mg/l and 20 mg/l of test substance were injected separately and in duplicate. The mean retention time determination for the test susbtance was repeated in order to increase confidence in the measurement.

Blank injections
Blank injections (of mobile phase) were made prior to the determination of column dead time and between any reference and test substance injections

Test pH
There was no pKa data available for the test substance therefore, the study was conducted at pH 2 and pH 10. This ensured that if the substance were ionisable both the ionised and non-ionised forms would be tested.


The reference substances used, and their respective log10Koc values were:


Substance Soil log10Koc (literature values)

Acetanilide 1.25
Atrazine 1.81
Isoproturon 1.86
Linuron 2.59
Naphthalene 2.75
1,2,3-Trichlorobenzene 3.16
Fenthion 3.31
Phenanthrene 4.09
ppDDT 5.63

The inert substance, used for determination of the column dead time, was sodium nitrate.

Results and discussion

Results: HPLC method

Details on results (HPLC method):
From the experimentally derived k' measurements and the literature Koc values of the reference substances, the equation of the fitted regression line was determined as log10Koc = a.1og10 k'+ b

where at pH2, a = 6.729 and b = 3.081
where at pH 10, a = 9.273 and b = 3.547

The coefficient of determination ((r2) of these data was calculated as 0.936 and 0.885 at pH2 and pHlO respectively, indicating a linear relationship between Log10 Koc and Log10 K'.

At pH2 the log10 k' for test substance was -0.358 at 10 mg/l and -0.336 at 20 mg/l, therefore, from the above equation the estimated log10 Koc for the test substance is <1.5.

At pH 10 at both 10 and 20 mg/l the log10 k' for test substance could not be calculated and the estimated log10 Koc is therefore, <1.5.

The test described has been validated for the quantitative estimation of values in the range 1.5 to 5.0. In those instances where the statistical treatment of the experimental data produces a calculated log10 Koc value outside of this range then the final result is quoted as either <1.5 or >5.0 as appropriate.

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Conclusions:
Log10 Koc of the test substance was less than 1.5 at pH 2 and at pH 10.