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Reference
Endpoint:
adsorption / desorption: screening
Type of information:
experimental study
Adequacy of study:
key study
Study period:
07/07/2011
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: This study was performed according to OECD guideline 121 with GLP statement. All validity criteria were fulfilled and no deviations were observed.
Reason / purpose:
reference to same study
Reason / purpose:
reference to other study
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))
Deviations:
no
Principles of method if other than guideline:
Not applicable
GLP compliance:
yes (incl. certificate)
Remarks:
2011-03-02
Type of method:
HPLC estimation method
Media:
soil/sewage sludge
Specific details on test material used for the study:
Details on properties of test surrogate or analogue material (migrated information):
PHYSICO-CHEMICAL PROPERTIES
- Water solubility: 2.597 to 4.0874 mg/L at 25°C (according to EPA Wskowwin v1.42 and EPA Waternt v1.01, respectively).
- Density: 920 Kg/m^3 at 20°C according to SDS.
Radiolabelling:
no
Test temperature:
During the analysis, the temperature was 22 +/- 0.5°C.
Details on study design: HPLC method:
EQUIPMENT
- Apparatus: Mettler Balance AG 245; Agilent Autosampler; Agilent HPLC pump; Agilent UV visible detector; LC-MS detection was not used in this study.
- Type: HPLC-UV
- Type, material and dimension of analytical (guard) column: Column = Agilent Zorbax CN; length = 15 cm; particle size = 5 µm; internal diameter = 2.1 mm; flow rate = 0.25 mL/min; injected volume = 5.0 µL; wavelength analysis = 210 nm.
- Detection system: UV

MOBILE PHASES
- Type: methanol-water 55-45 v/v
- pH: pH 7 at 25°C
- Solutes for dissolving test and reference substances: methanol

DETERMINATION OF DEAD TIME
- Method: by inert substances which are not retained by the column (formamide)

REFERENCE SUBSTANCES
- Identity: formamide, acetanilide, methyl benzoate, triadimenol, naphtalene, phenanthrene, 1,1-bis(4-chlorophenyl)-2,2,2-trichloroethane

DETERMINATION OF RETENTION TIMES
- Quantity of test substance introduced in the column: 5.0 µL
- Quantity of reference substances: 5.0 µL
- Intervals of calibration: the injection sequence was analytical reference items solution, test item solution, blank methanol, analytical reference items solution 3 times, blank methanol, test item solution.

REPETITIONS
- Number of determinations: 3

EVALUATION
- Calculation of capacity factors k': k' = (t.r-t.0)/t.0 where t.r is HPLC retention time of test and reference substance (min) and t.0 is HPLC dead time (min).
- Calculation of retention times: yes
- Determination of the log Koc value: log Koc = a + b x log k' where a and b regression coefficients are obtained by linearly regressing the log of partition coefficients of reference substances against the log of capacity factors of the same substances.
Key result
Type:
log Koc
Value:
3.78
Temp.:
22 °C
Remarks on result:
other: The results issued from the 3 determinations (3.78, 3.78, 3.78) is in the guideline tolerance for repeatability (+/- 0.25 log units)
Details on results (HPLC method):
- Retention times of reference substances used for calibration: see table 1 in "Any other information on results incl. tables".
- Details of fitted regression line (log k' vs. log Koc): log Koc = 3.1123 log k' + 2.8809 with r² = 0.9798.
- Graph of regression line: see in "Attached background material".
- Average retention data for test substance: Injection 1 = retention time 6.27 min / log Koc 3.78. Injection 2 = retention time 6.27 min / log Koc 3.78. Injection 3 = retention time 6.27 min / log Koc 3.78.
Statistics:
None

Table 5.4.1/1: Retention times of reference substances used for calibration

Products

Mean retention time (min)

Value of the capacity factor k’

Value of log k’

Value of log Koc

Formamide

2.13

-

-

-

Acetanilide

2.64

0.2394366183

-0.62080943

1.25

Methyl benzoate

3.12

0.4647887312

-0.33274441

1.80

Triadimenol

3.80

0.7840375628

-0.10566313

2.40

Naphtalene

4.49

1.1079812220

0.04453240

2.75

Phenanthrene

7.71

2.6197183370

0.41825460

4.09

DDT

15.58

6.3145539780

0.80034268

5.63

Validity criteria fulfilled:
yes
Conclusions:
The mean value of the log Koc is 3.78. This result issued from the 3 determinations is in the guideline tolerance for repeatability (log Koc at 3.78, 3.78 and 3.78).
Executive summary:

This study was performed according to OECD Guideline 121 with GLP statement to determine the adsorption coefficient of the test item applying the HPLC method.

The test item is injected on a liquid chromatography system where a partition occurs between the stationary phase of the column (Agilent Zorbax CN) and the eluent phase (Methanol-water 55/45 v/v). Chemicals are retained according to their adsorption coefficient. Therefore a relation exists between the retention time and the adsorption coefficient of a chemical product. The adsorption coefficient (Koc) is determined through the relation: log Koc = a + b x log k' where k' is the capacity factor (k' = (t.r-t.0) / t.0 where t.r is the HPLC retention time of test and reference substance and t.0 is the HPLC dead time) and a and b regression coefficients are obtained by linearly regressing the log of partition coefficients of reference substances against the log of capacity factors of the same substances. The dead time (t.0) is measured by use of formamide, which is not retained on the column. A correlation of log k' versus log Koc is plotted for the appropriate reference substances. The determination of the HPLC retention times of the test item and of the analytical reference items was made twice. The temperature during the analytical sequence (analytical reference items solution, test item solution, blank methanol, analytical reference items solutions 3 times, blank methanol, test item solution) was 22 +/- 0.5°C.

Using the capacity factor and the partition coefficient of the reference items, the following calibration curve was obtained: log Koc = 3.1123 log k' + 2.8809 with r² = 0.9798. The log Koc values were calculated using the precedent regression equation with the corresponding retention time (6.27, 6.27 and 6.27 min). The mean value of the log Koc is 3.78. This result issued from the 3 determinations is in the guideline tolerance for repeatability (log Koc at 3.78, 3.78 and 3.78).

Description of key information

OECD 121, GLP, key study, validity 1:
Log Koc = 3.78 at 22 ± 0.5 °C.

Key value for chemical safety assessment

Koc at 20 °C:
6 025.6

Additional information

One key study is available and assessed the adsorption coefficient of the test substance applying the procedure described in the OECD Guideline 121 with GLP statement.


The test item is injected on a liquid chromatography system where a partition occurs between the stationary phase of the column (Agilent Zorbax CN) and the eluent phase (Methanol-water 55/45 v/v). Chemicals are retained according to their adsorption coefficient. Therefore a relation exists between the retention time and the adsorption coefficient of a chemical product. A correlation of log k' (k' is the capacity factor (k' = (t.r-t.0) / t.0 where t.r is the HPLC retention time of test and reference substance and t.0 is the HPLC dead time)) versus log Koc is plotted for the appropriate reference substances. The determination of the HPLC retention times of the test item and of the analytical reference items was made twice.


The adsorption coefficient (Koc) of the test item is determined through the relation: log Koc = 3.1123 log k' + 2.8809 with r² = 0.9798. The temperature during the analytical sequence (analytical reference items solution, test item solution, blank methanol, analytical reference items solutions 3 times, blank methanol, test item solution) was 22 ± 0.5°C.


The log Koc values were calculated using the precedent regression equation with the corresponding retention time (6.27, 6.27 and 6.27 min). The mean value of the log Koc is 3.78. This result issued from the 3 determinations is in the guideline tolerance for repeatability (log Koc at 3.78, 3.78 and 3.78).