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Endpoint:
adsorption / desorption: screening
Type of information:
experimental study
Adequacy of study:
supporting study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: GLP and Guideline study; however, due to surface-active properties and large molecular size of the test substance, which are known confounding factors for the HPLC estimation method, this study are flagged as "supporting study" with KC2.
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:
30°C
Details on study design: HPLC method:
EQUIPMENT
HPLC conditions
Column Phenosphere NEXT 5µ CN (250 x 4.6 mm id)
Mobile phase: methanol/water (55:45), pH = 5.4,
Column temperature = 30ºC
Flow rate = 1 ml/min
Detector: Refractive index (and Evaporative Light Scattering Detector)
Injection volume = 10 µl

- Apparatus: Agilent Technologies 1200, incorporating autosampler, workstation and refractive index detector.
- Type, material and dimension of analytical (guard) column: Phenosphere NEXT 5 u CN (250 x 4.6 mm id)


MOBILE PHASES
- Type: Methanol: reverse osmosis water (55:45)


DETERMINATION OF DEAD TIME
- Method: by means of homologous series / by inert substances which are not retained by the column


REFERENCE SUBSTANCES
- Identity: Diclofop-methyl


DETERMINATION OF RETENTION TIMES
- Quantity of test substance introduced in the column: 10 ul
- Quantity of reference substances: 10ul
- Intervals of calibration:



EVALUATION
- Calculation of capacity factors k': k= retention time - dead time / dead time
Analytical monitoring:
not required
Details on sampling:
- Concentrations:
- Sampling interval: 2
- Sample storage before analysis: Not specified
Type:
Koc
Value:
< 17.8
Type:
log Koc
Value:
< 1.25
Details on results (HPLC method):
Linear regression of log10Koc and log10k (where k = capacity factor) revealed the following equation

Log10Koc = -1.564 log10k + 0.419 (r = 0.988)
Validity criteria fulfilled:
yes
Conclusions:
The adsorption coefficient (Koc) of the test material has been detremined to be <17.8, log 10 Koc < 1.25. The test substance exhibits weak surface-active properties, and is a UVCB mixture of homologous components; therefore the HPLC method may produce results which are confounded by these properties.
Endpoint:
adsorption / desorption, other
Remarks:
adsorption
Type of information:
(Q)SAR
Adequacy of study:
supporting study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Accepted estimation method, using transparent calculation algorithm and training set.
Justification for type of information:
QSAR prediction: migrated from IUCLID 5.6
Reason / purpose:
reference to same study
Principles of method if other than guideline:
The organic carbon-normalized soil/water partition coefficient (Koc) was estimated using the first-order molecular connectivity-based software KOCWIN (Meylan, W., P.H. Howard and R.S. Boethling. 1992. Molecular topology/fragment contribution method for predicting soil sorption coefficients. Environ. Sci. Technol. 26: 1560-1567). Estimates were made for the lowest and highest molecular weight homologues of the UVCB substance. The range of Koc values for these homologues are reported here, and the lowest value of Koc is used in derivation of conservative PNECsoil and PNECsediment values using the equilibrium partitioning method.
GLP compliance:
no
Type of method:
other: Estimation by QSAR
Media:
other: estimated oganic carbon-normalized adsorption (Koc)
Specific details on test material used for the study:
Details on properties of test surrogate or analogue material (migrated information):
not applicable
Radiolabelling:
no
Test temperature:
not applicable
Details on study design: HPLC method:
not applicable
Analytical monitoring:
no
Details on sampling:
not applicable
Details on matrix:
not applicable
Details on test conditions:
not applicable
Computational methods:
The PCKOCWIN software uses a molecular connectivity index-based algorithm to derive estimates of Koc. The predictive algorithm is derived from an extensive dataset of evaluated measured Koc values for a wide variety of substance classes. This training set includes various amine-, alcohol-, and ether-bearing substances; and thus any specific modes of adsorption which are imparted by these functional groups are reflected in the predicted values for substances having these same functional groups. For example, the cation-exchange mode of adsorption which occurs for aliphatic and aromatic amine substances can be accurately predicted because the training set included measured adsorption coefficients for several of these substances (as illustrated below). The PCKOCWIN estimation method and associated training set are fully described in the cited publication by Meylan et al., 1992.
Type:
Koc
Value:
10
Temp.:
25 °C
Remarks on result:
other: Estimated Koc for lowest and highest MW homologues of the UVCB substance
Type:
log Koc
Value:
1
Temp.:
25 °C
Remarks on result:
other: Estimated log Koc values for lowest and highest MW homologues of the UVCB substance
Details on results (HPLC method):
not applicable
Adsorption and desorption constants:
not applicable
Recovery of test material:
not applicable
Concentration of test substance at end of adsorption equilibration period:
not applicable
Concentration of test substance at end of desorption equilibration period:
not applicable
Transformation products:
not measured
Details on results (Batch equilibrium method):
not applicable
Statistics:
not applicable
Validity criteria fulfilled:
yes
Conclusions:
The estimated Koc value for homologous components of this UVCB substance was 10 L/kg for the full range of homologues (low -high molecular weight). The components of this UVCB substance can be regarded as having low affinity for adsorption to soils and activated sludge biosolids.

Description of key information

In accordance with Column 2 of REACH Annex IX, the study does not need to be conducted as the substance can be expected to have a low potential for sorption (log Kow ≤3). The estimated Koc value for homologous components of this UVCB substance was 10 L/kg for the full range of homologues (low -high molecular weight).  The components of this UVCB substance can be regarded as having low affinity for adsorption to soils and activated sludge biosolids.

Key value for chemical safety assessment

Additional information

The KOCWIN software is shown to produce estimated log Koc values which are typically within 0.3 log units of measured values for a set of amine- and alcohol-bearing substances which are expected to have log Koc values bracketing that of the test substance. Because the software training set includes measured Koc values for several aliphatic and aromatic amine substances, it is expected to provide accurate predictions of adsorption for amine-initiated NLP polyols, which may adsorb to soil by a combination of cation-exchange and hydrophobic partitioning mechanisms. These results are therefore expected to provide a more realistic estimation of adsorption potential than the HPLC estimation method, which may be confounded by the surface-activity of the test substance components and lack of relevant reference substances (i.e., alcohols, ethers, amines) employed in the OECD 121 guideline.

Adsorption/Desorption was investigated using the OECD 121 method, and results indicated Koc <17.8 and Log Koc <1.25 at pH 5.4.