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Adsorption / desorption

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Reference
Endpoint:
adsorption / desorption: screening
Type of information:
experimental study
Adequacy of study:
key study
Study period:
08 November 2010 - 14 December 2010
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline 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
GLP compliance:
yes (incl. certificate)
Type of method:
HPLC estimation method
Media:
soil/sewage sludge
Radiolabelling:
no
Test temperature:
22.5°C
Details on study design: HPLC method:
EQUIPMENT
- Apparatus: HPLC
- Type, material and dimension of analytical (guard) column: Supelco 25cm 4.6mm
- Detection system: wave length 210 nm (UV)

MOBILE PHASES
- Type: Methanol / water 70/30 v/v

DETERMINATION OF DEAD TIME
- Method: with reference item

REFERENCE SUBSTANCES
- Identity: thiourea, Acetanilide, Phenanthrene, 4,4’-DDT, Isoproturon, Pyrazophos, 1,2,3-Trichlorobenzene

DETERMINATION OF RETENTION TIMES
- Quantity of test substance introduced in the column: A quantity of about 1 g (to the nearest ± 0.1 mg) of the test item was weighed into a 100-mL volumetric flask. The volume was made up with methanol. The solution was diluted 20 times, then 10 times with methanol.
- Quantity of reference substances:
acetanilide: 10 mg into a 100-mL volumetric flask diluted 20 times
isoproturon: 20 mg into a 25-mL volumetric flask diluted 160 times
1,2,3-trichlorobenzene: 20 mg into a 100-mL volumetric flask diluted 40 times
pyrazophos: 20 mg into a 100-mL volumetric flask diluted 10 times
phenanthrene: 20 mg into a 50-mL volumetric flask, diluted 200 times
4,4’-DDT: 10 mg into a 100-mL volumetric flask diluted 5 times.
- Intervals of calibration: log Koc values of reference items were 1.25, 1.86, 3.16, 3.65, 4.09 and 5.63

REPETITIONS
- Number of determinations: 2

EVALUATION
- Determination of the log Koc value: Log k’ = a log Koc + b
Type:
log Koc
Value:
ca. 4.88 dimensionless
Temp.:
22.5 °C
Remarks on result:
other: OC not applicable (screening), mean of two values
Type:
Koc
Value:
>= 74 131 - <= 77 624 L/kg
Temp.:
22.5 °C
Phase system:
solids-water in sediment
Type:
Kp
Value:
ca. 3 793 L/kg
Temp.:
22.5 °C
Remarks on result:
other: calculated from Koc
Phase system:
solids-water in sediment
Type:
log Kp
Value:
ca. 3.58 L/kg
Temp.:
22.5 °C
Remarks on result:
other: calculated from Kp
Details on results (HPLC method):
- Retention times of reference substances used for calibration: log Koc values of reference items were 3.47, 3.67, 4.19, 4.56, 4.71, 5.62 min
- Details of fitted regression line (log k' vs. log Koc): log k’ = 0.240 log koc – 1.372 or log k’ = 0.239 log koc – 1.371 (2 runs)
- Average retention data for test substance: 5.31 or 5.29 min

Calculation of Kpsediment has been done to help determining the need for sediment testing (ECHA Guidance R16, 2008):

Kpsed = Foc-sed * Koc

Kpsed: partition coefficient solid-water in sediment [L.kg-1]

Foc-sed: weight fraction of organic carbon in sediment [kg.kg-1] = 0.05

Therefore Kpsed= 0.05 * 104.88= 3793

The logKpsedis calculated from 3793.

[LogKoc: 4.88]

Validity criteria fulfilled:
not specified
Remarks:
no criteria in guideline
Conclusions:
The log value of the adsorption / desorption coefficient (log Koc) of BAB is equal to 4.88.

Description of key information

The log Koc has been experimentally calculated with a study according to the OECD 121 guideline. The mean of two runs is the value used to calculate the absorption coefficient Koc, which is used to estimate the Kpsed and log Kpsed.

The estimated values of log Koc for the different components using KOCWIN are consistent with the experimental value for the whole BAB.

Key value for chemical safety assessment

Koc at 20 °C:
75 858

Other adsorption coefficients

Type:
log Kp (solids-water in sediment)
Value in L/kg:
3.58
at the temperature of:
22.5 °C

Additional information