Registration Dossier

Administrative data

Endpoint:
adsorption / desorption: screening
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
1 (reliable without restriction)

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2014

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:
soil

Test material

Reference
Name:
Unnamed
Type:
Constituent

Study design

HPLC method

Details on study design: HPLC method:
A liquid chromatograph, comprising a pulse-free pump, injection valve with injection loopand suitable detector, was used in conjunction with a commercially available analyticalcolumn packed with a solid phase containing a moderately polar stationary phase withlipophilic and polar moieties (e.g. cyano-propyl bonded phase)., The followingmobile phases were used :methanol/water (55/45% v/v)- methanol/0.01M citrate-buffer pH 6.0 (55/45% v/v)HPLC grade methanol and distilled water were used to prepare the eluting solvent. Themobile phase was degassed before use. If methanol/water mixtures were not appropriate,other organic solvent/water mixtures were be tried, e.g. ethanol/water or acetonitrile/watermixtures.Measurements were made on ionisable substances at selected pH values by appropriatebuffering of the HPLC eluent.Isocratic elutions were employed and the temperature during the measurements wasrecorded...A minimum of 6 standard reference compounds were injected and the retention timesdeterminedAt least one standard was above and one below the expectedvalue of the test substance. Chemicals injected onto the column move along it by partitioningbetween the mobile phase and the stationary phase. The velocity of each component therebydepends on the degree of adsorption on the stationary phase. The dual nature of the stationaryphase allows for interaction of polar and apolar parts of a molecule in a similar way as is thecase for soil. This enables the relationship between the retention time on such a column andthe adsorption coefficient on the organic parts of the soil to be established. The capacityfactor, k, was determined for reference compounds from the expression:k = (tr - t0)/t0where tr is the retention time of the compound and t0 is the deadtime, i.e. the average time asolvent molecule needs to pass through the column. The deadtime was obtained using anunretained molecule, e.g. formamide, urea, thiourea or sodium nitrate.The corresponding logarithms of the capacity factors, log10k, were calculated and plotted asa function of log10Koc. The retention time of the test substance was determined in duplicate,and log10Koc calculated by interpolation of the calculated capacity factor on the calibrationgraph.For very low and very high adsorption coefficients, extrapolation was necessary.Especially in these cases, care has been taken concerning the confidence limits of theregression curve and the validity of the extrapolation.

Results and discussion

Adsorption coefficient
Type:
log Koc
Value:
4.4 - 5.7

Results: HPLC method

Details on results (HPLC method):
Soil adsorption: a log10Koc range of 4.4 to 5.7 was determined for the main components of the test substance.

Any other information on results incl. tables

A calibration plot of log10k versus log10Kocwas constructed for the reference standards. The logarithms of the capacity factors for the test substance were then calculated and the log10Kocvalues were determined by interpolation (Table 1).

The main components of the test substance were found to have log10Kocvalues between 4.4 and 5.7.

Table 1         HPLC determination of log10Koc 

 

Sample

Component

tr(minutes)

k

log10k

log10Koc

 

 

 

 

 

 

Standard Run A

Acetanilide

3.354

0.208

-0.681

1.3

(t0= 2.776 minutes)

Nitrobenzene

4.069

0.466

-0.332

2.4

 

Naphthalene

4.723

0.701

-0.154

2.8

 

2-Methylnaphthalene

5.008

0.804

-0.095

3.9

 

Anthracene

5.563

1.004

0.002

4.4

 

DDT

8.086

1.913

0.282

5.6

 

 

 

 

 

 

Sample A

Test substance

5.902 - 8.621

1.123 - 2.101

0.050 - 0.322

4.4 - 5.7

(t0= 2.780 minutes)

 

 

 

 

 

 

 

 

 

 

 

Sample B

Test substance

5.901 - 8.620

1.123 - 2.101

0.050 - 0.322

4.4 - 5.7

(t0= 2.780 minutes)

 

 

 

 

 

 

 

 

 

 

 

Standard Run B

Acetanilide

3.355

0.208

-0.682

1.3

(t0= 2.777 minutes)

Nitrobenzene

4.070

0.466

-0.332

2.4

 

Naphthalene

4.724

0.701

-0.154

2.8

 

2-Methylnaphthalene

5.009

0.804

-0.095

3.9

 

Anthracene

5.564

1.004

0.002

4.4

 

DDT

8.086

1.912

0.281

5.6

 

 

 

 

 

 

 

Linear regression (based on mean of standard runs A and B): log10Koc= 4.70 log10k + 4.14

Applicant's summary and conclusion

Executive summary:

Soil adsorption: a log10Koc range of 4.4 to 5.7 was determined for the main components of the test substance.