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Adsorption / desorption

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Endpoint:
adsorption / desorption: screening
Type of information:
experimental study
Adequacy of study:
weight of evidence
Study period:
30.03.2006
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
guideline study with acceptable restrictions
Remarks:
In deviation from guideline only 4 reference substances were used.
Qualifier:
according to guideline
Guideline:
OECD Guideline 121 (Estimation of the Adsorption Coefficient (Koc) on Soil and on Sewage Sludge using High Performance Liquid Chromatography (HPLC))
Deviations:
yes
Remarks:
(only four reference substances used)
GLP compliance:
not specified
Remarks:
used in a weight-of-evidence approach
Type of method:
HPLC estimation method
Media:
soil
Test temperature:
22°C
Details on study design: HPLC method:
EQUIPMENT
- Apparatus: HPLC
- Type: not reported
- Type, material and dimension of analytical (guard) column: a 125.4 mm Lichrospher 100 CN 5µ
- Detection system: RI

MOBILE PHASES
- Type: methanol/aqueous citrate buffer pH 6 (55:45)
- Experiments with additives carried out on separate columns: yes
- pH: 6
- Solutes for dissolving test and reference substances: not reported

DETERMINATION OF DEAD TIME
- Method: by means of homologous series / by inert substances which are not retained by the column: dead time was determined by injecing acetonitrile in water (dead time: 1.39 min)

REFERENCE SUBSTANCES
- Identity:
methyl benzoate (log Koc=1.8)
naphthaline (log Koc=2.75)
phenanthrene (log Koc=4.09)
phenyl benzoate (log Koc=2.94

DETERMINATION OF RETENTION TIMES
- Quantity of test substance introduced in the column: 2 mg/mL of the test substance (dodecyl amido propylbetaine: ca. 1.5 mg/mL, tetradecyl amido propylbetaine: ca. 0.5 mg/mL
- Quantity of reference substances: ca. 2 mg/mL
- Intervals of calibration: <1h

REPETITIONS
- Number of determinations: not reported

EVALUATION
- Calculation of capacity factors k': the capacity feactors were calculated from the dead time and the retention times
- Determination of the log Koc value: log K'=0.3691 log Koc - 0.7345
Type:
Koc
Remarks:
C12 derivate
Value:
ca. 320 L/kg
Temp.:
20 °C
Type:
log Koc
Remarks:
C12 derivate
Value:
2.5 dimensionless
Temp.:
20 °C

In a screening study conducted according to OECD Guideline 121 (Estimation of the Adsorption Coefficient (Koc) on Soil and on Sewage Sludge using High Performance Liquid Chromatography (HPLC)) the log Koc value of C12 AAPB was determined to be 2.5 (Koc: ca. 320) based on a corrected dead time value. Based on this result and taking into account the classification scheme of Blume and Ahlsdorf (1993) a medium sorption onto soil organic matter is to be expected.

Validity criteria fulfilled:
yes
Conclusions:
Based on the experimental results (log Koc=2.5; Koc: ca. 320) a medium sorption onto soil organic matter is to be expected for C12 AAPB.
Executive summary:

In a screening study conducted according to OECD Guideline 121 (Estimation of the Adsorption Coefficient (Koc) on Soil and on Sewage Sludge using High Performance Liquid Chromatography (HPLC)) the log Koc value of C12 AAPB was determined to be 2.5 (Koc: ca. 320) based on a corrected dead time value. Based on this result and taking into account the classification scheme of Blume and Ahlsdorf (1993) a medium sorption onto soil organic matter is to be expected.

Endpoint:
adsorption / desorption: screening
Type of information:
experimental study
Adequacy of study:
weight of evidence
Study period:
30.03.2006
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
guideline study with acceptable restrictions
Remarks:
In deviation from guideline only 4 reference substances were used.
Qualifier:
according to guideline
Guideline:
OECD Guideline 121 (Estimation of the Adsorption Coefficient (Koc) on Soil and on Sewage Sludge using High Performance Liquid Chromatography (HPLC))
Deviations:
yes
Remarks:
(only four reference substances used)
GLP compliance:
not specified
Remarks:
used in a weight-of-evidence approach
Type of method:
HPLC estimation method
Media:
soil
Test temperature:
22°C
Details on study design: HPLC method:
EQUIPMENT
- Apparatus: HPLC
- Type: not reported
- Type, material and dimension of analytical (guard) column: a 125.4 mm Lichrospher 100 CN 5µ
- Detection system: RI

MOBILE PHASES
- Type: methanol/aqueous citrate buffer pH 6 (55:45)
- Experiments with additives carried out on separate columns: yes
- pH: 6
- Solutes for dissolving test and reference substances: not reported

DETERMINATION OF DEAD TIME
- Method: by means of homologous series / by inert substances which are not retained by the column: dead time was determined by injecing acetonitrile in water (dead time: 1.39 min)

REFERENCE SUBSTANCES
- Identity:
methyl benzoate (log Koc=1.8)
naphthaline (log Koc=2.75)
phenanthrene (log Koc=4.09)
phenyl benzoate (log Koc=2.94

DETERMINATION OF RETENTION TIMES
- Quantity of test substance introduced in the column: 2 mg/mL of the test substance (dodecyl amido propylbetaine: ca. 1.5 mg/mL, tetradecyl amido propylbetaine: ca. 0.5 mg/mL
- Quantity of reference substances: ca. 2 mg/mL
- Intervals of calibration: <1h

REPETITIONS
- Number of determinations: not reported

EVALUATION
- Calculation of capacity factors k': the capacity feactors were calculated from the dead time and the retention times
- Determination of the log Koc value: log K'=0.3691 log Koc - 0.7345
Type:
Koc
Remarks:
C14 derivate
Value:
ca. 3 200 L/kg
Temp.:
20 °C
Type:
log Koc
Remarks:
C14 derivate
Value:
3.5 dimensionless
Temp.:
20 °C
Validity criteria fulfilled:
yes
Conclusions:
The soil sorption coefficients (log Koc) of C14 AAPB was determined to be 3.5. Based on this result a high sorption onto soil organic matter is to be expected.
Executive summary:

In a screening study conducted according to OECD Guideline 121 (Estimation of the Adsorption Coefficient (Koc) on Soil and on Sewage Sludge using High Performance Liquid Chromatography (HPLC)) the log Koc values of C12 AAPB and C14 AAPB were determined. Based on a corrected dead time value (see Erratum), the log Koc of C14 AAPB was determined to be 3.5 (Koc: ca. 3200). Based on this result and taking into account the classification scheme of Blume and Ahlsdorf (1993) a high sorption onto soil organic matter is to be expected.

Description of key information

 Reliable experimental results for Koc are available only for C12 and C14 AAPB from a non-GLP study. Therefore in addition, for all components of C8-18 AAPB soil sorption coefficients were calculated using ACD and EUSES. The weighted mean Koc and log Koc were calculated according to weight fractions of fatty acid chain length distribution, resulting in a weighted mean Koc of 8191 L/kg and a mean log Koc of 3.91. 

Key value for chemical safety assessment

Koc at 20 °C:
8 191

Other adsorption coefficients

Type:
log Kp (solids-water in soil)
Value in L/kg:
1.16
at the temperature of:
25 °C

Other adsorption coefficients

Type:
log Kp (solids-water in sediment)
Value in L/kg:
1.56
at the temperature of:
25 °C

Other adsorption coefficients

Type:
log Kp (solids-water in suspended matter)
Value in L/kg:
1.86
at the temperature of:
25 °C

Other adsorption coefficients

Type:
log Kp (solids-water in raw sewage sludge)
Value in L/kg:
2.33
at the temperature of:
25 °C

Other adsorption coefficients

Type:
log Kp (solids-water in settled sewage sludge)
Value in L/kg:
2.33
at the temperature of:
25 °C

Other adsorption coefficients

Type:
log Kp (solids-water in activated sewage sludge)
Value in L/kg:
2.43
at the temperature of:
25 °C

Other adsorption coefficients

Type:
log Kp (solids-water in effluent sewage sludge)
Value in L/kg:
2.43
at the temperature of:
25 °C

Additional information

A weight of evidence approach was used for evaluation, as the experimental determined values are used as training structure for the ACD calculated values.

In a screening study conducted according to OECD Guideline 121 (Estimation of the Adsorption Coefficient (Koc) on Soil and on Sewage Sludge using High Performance Liquid Chromatography (HPLC)) the log Koc values of C12 and C14 AAPB were determined. Based on a corrected dead time value, the log Koc of C12 and C14 AAPB were determined to be 2.5 (Koc: ca. 320; C12 derivate) and 3.5 (Koc: ca. 3200; C14 derivate), respectively. Based on these results and taking into account the classification scheme of Blume and Ahlsdorf (1993) a medium (C12 derivate) and high sorption (C14 derivate) onto soil organic matter is to be expected.

Based on the Koc value determined by measurement, C12 AAPB was used as training structure for the ACD software and Kow values were calculated for C8, C10, C14, C16 and C18 AAPB (for this calculation to the IUCLID the following justification documents are attached: QSAR prediction report format (QPRF) and QSAR model reporting format (QMRF)). The soil sorption coefficient of AAPB containing C8-, C10-, C12-, C14-, C16-, and C18 fatty acids was calculated using the guideline conform EUSES algorithm for non hydrophobics. The calculation yielded Koc values of 89.3 (C8 derivate), 303 (C10 derivate), 726 (C12 derivate), 4870 (C14 derivate), 16500 (C16 derivate), and 56000 (C18 derivate). According to the classification scheme of Blume & Ahlsdorf (1993), a low (C8 derivate), medium (C10 derivate), high (C12 and C14 derivates), and very high (C16 and C18 derivates) sorption onto soil organic matter is to be expected.

As reported in HERA (2007), the Koc values for AAPB containing C8-, C10-, C12-, C14-, C16-, and C18 fatty acids were calculated using EPIWIN v3.11, PCKOCWIN v1.67. The calculation yielded Koc values of 264.7 (C8 derivate), 900.5 (C10 derivate), 3063 (C12 derivate), 10420 (C14 derivate), 35450 (C16 derivate), and 120600 (C18 derivate). According to the classification scheme of Litz (1990) these values indicate a low to very high sorption potential to the organic matter of soils and sediments depending on the chain length.

Based on the experimental determined Koc values of C12 and C14 AAPB, the Koc values calculated with EPIWIN seem to overestimate soil sorption. The values calculated with ACD/EUSES (reasoned in separate documents (QPRF, QMRF attached to IUCLID)) Koc and Kow values were used for further calculations (environmental exposure and risk assessment).