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Endpoint:
adsorption / desorption: screening
Type of information:
experimental study
Adequacy of study:
key study
Study period:
8 January 2010-12 january 2010
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: A GLP study undertaken to current EU and OECD test guidelines
Qualifier:
according to
Guideline:
EU Method C.19 (Estimation of the Adsorption Coefficient (KOC) on Soil and Sewage Sludge Using High Performance Liquid Chromatography (HPLC))
Deviations:
no
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
Type of method:
HPLC estimation method
Media:
soil
Radiolabelling:
no
Test temperature:
25°C
Details on study design: HPLC method:
EQUIPMENT
- Apparatus: Liquid Chromatograph
- Type: Agilent 1200 Series
- Type, material and dimension of analytical (guard) column: Hypersil CPS (25 cm x 4.6 mm internal diameter)


- Detection system: UV set at 210 nm

MOBILE PHASES
- Type: Methanol:water (55:45 v/v)
- Experiments with additives carried out on separate columns: no
- pH: no data
- Solutes for dissolving test and reference substances: none

DETERMINATION OF DEAD TIME
- Method: by an inert substance which is not retained by the column

REFERENCE SUBSTANCES
- Identity: formamide

DETERMINATION OF RETENTION TIMES
- Quantity of test substance introduced in the column: 20 µl at 212 mg/l
- Quantity of reference substances: 20 µl at 200 mg/l
- Intervals of calibration: calibrated as part of the study

REPETITIONS
- Number of determinations: 2

EVALUATION
- Calculation of capacity factors k': tr-to/to
- Calculation of retention times: tr-to
- Determination of the log Koc value: log10Koc = 3.52 log10k + 4.16
Type:
log Koc
Value:
3.2 dimensionless
Temp.:
25 °C
Type:
Koc
Value:
1 750 L/kg
Temp.:
25 °C
Details on results (HPLC method):
- Retention times of reference substances used for calibration: 3.155 mins
- Details of fitted regression line (log k' vs. log Koc): log10Koc = 3.52 log10k + 4.16
- Graph of regression line attached: yes
- Average retention data for test substance: 4.889 mins (additional peak with shorter retention time of 3.151 min, but not included in calculation)

A value of log10Koc for Oxooil LS 9 of 3.2 was obtained. This result was determined for the primary chromatographic component, although it was evident that there were some minor components of shorter retention time and, hence, lower log10Koc value.

Conclusions:
Oxooil LS 9 was determined to have a log10Koc value of 3.2 (equivalent Koc = 1750).
Endpoint:
adsorption / desorption: screening
Type of information:
(Q)SAR
Adequacy of study:
supporting study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
results derived from a valid (Q)SAR model and falling into its applicability domain, with adequate and reliable documentation / justification
Justification for type of information:
1. SOFTWARE
EpiSuite v4.11, US EPA, 2012

2. MODEL (incl. version number)
KOCWIN v2.00 (MCI method)

3. SMILES OR OTHER IDENTIFIERS USED AS INPUT FOR THE MODEL
see atteched file (Koc_QSAR justification.pdf)


4. SCIENTIFIC VALIDITY OF THE (Q)SAR MODEL
- Defined endpoint: Koc
MCI (molecular connectivity index) method
The equation derived by the non-polar (no correction factor) regression is:
log Koc = 0.5213 MCI + 0.60
(n = 69, r2 = 0.967, std dev = 0.247, avg dev = 0.199)
for comparison, the previous version of PCKOCWIN used a very similar equation:
log Koc = 0.53 MCI + 0.62
Adding in the correction factor regression yields the final MCI equation:
log Koc = 0.5213 MCI + 0.60 + ΣPfN
where ΣPfN is the summation of the products of all applicable correction factor coefficients multiplied by the number of times (N) that factor is counted for the structure.

- Defined domain of applicability:
Currently there is no universally accepted definition of model domain. However, users may wish to
consider the possibility that log P estimates are less accurate for compounds outside the MW
range of the training set compounds, and/or that have more instances of a given fragment than the
maximum for all training set compounds. It is also possible that a compound may have a functional
group(s) or other structural features not represented in the training set, and for which no fragment
coefficient was developed. These points should be taken into consideration when interpreting
model results.

Training Set Molecular Weights:
Minimum MW: 32.04
Maximum MW: 665.02
Average MW: 224.4
Validation Molecular Weights:
Minimum MW: 73.14
Maximum MW: 504.12
Average MW: 277.8

- Appropriate measures of goodness-of-fit and robustness and predictivity:
Overall, the MCI methodology is somewhat more accurate than the Log Kow methodology, although both methods yield good results. If the Training datasets are combined in to one dataset of 516 compounds (69 having no corrections plus 447 with corrections), the MCI methodology has an r2, standard deviation and average deviation of 0.916, 0.330 and 0.263, respectively.

5. APPLICABILITY DOMAIN
- Descriptor domain: The components of the substance are within the molecular weight range of the training set compounds, and all fragments are represented in the training set. Thus, it is concluded, that the substance is within the applicability domain.
- Similarity with analogues in the training set: several linear and branched alkanes and alkenes, which are considered to be similar, are present in the training set.

6. ADEQUACY OF THE RESULT
The QSAR prediction is valid and of good reliability. Thus, the result is adequate for chemical safety assessment.
Principles of method if other than guideline:
Estimation of the Koc of the components by QSAR (EpiSuite v4.11, US EPA, 2012; KOCWIN v2.00 (MCI method))
GLP compliance:
no
Type of method:
other: QSAR
Remarks:
EpiSuite v4.11, US EPA, 2012; KOCWIN v2.00 (MCI method)
Key result
Type:
Koc
Remarks:
weighted mean
Value:
369.6 L/kg
Temp.:
25 °C
Type:
Koc
Value:
>= 26.94 - <= 436.8 L/kg
Temp.:
25 °C

for details see attachment

Conclusions:
The Koc of the constituents was estimated using EpiSuite v4.11, US EPA, 2012, KOCWIN v2.00 (MCI method) in batch mode, resulting in Koc values ranging from 26.94 to 436.8 L/kg with a weighted mean Koc of 369.6.

Description of key information

Oxooil LS9 has a Koc value of 1750 (log Koc = 3.2), measured according to guideline OECD 121.

Key value for chemical safety assessment

Koc at 20 °C:
1 750

Other adsorption coefficients

Type:
log Kp (solids-water in soil)
Value in L/kg:
1.54
at the temperature of:
20 °C

Other adsorption coefficients

Type:
log Kp (solids-water in sediment)
Value in L/kg:
1.94
at the temperature of:
20 °C

Other adsorption coefficients

Type:
log Kp (solids-water in suspended matter)
Value in L/kg:
2.24
at the temperature of:
20 °C

Other adsorption coefficients

Type:
log Kp (solids-water in raw sewage sludge)
Value in L/kg:
2.72
at the temperature of:
20 °C

Other adsorption coefficients

Type:
log Kp (solids-water in settled sewage sludge)
Value in L/kg:
2.72
at the temperature of:
20 °C

Other adsorption coefficients

Type:
log Kp (solids-water in activated sewage sludge)
Value in L/kg:
2.81
at the temperature of:
20 °C

Other adsorption coefficients

Type:
log Kp (solids-water in effluent sewage sludge)
Value in L/kg:
2.81
at the temperature of:
20 °C

Additional information

Oxooil LS9 has a Koc value of 1750 (log Koc = 3.2), measured according to guideline OECD 121. This result was determined for the primary chromatographic component, although there were some minor components of shorter retention time and, hence, lower Koc value.

Since the substance is rather volatile and therefore difficult to test, in addition, the Koc of the constituents of Oxooil LS9 was estimated using EpiSuite v4.11, US EPA, 2012, KOCWIN v2.00 (MCI method) in batch mode, resulting in Koc values ranging from 26.94 to 436.8 L/kg with a weighted mean Koc of 369.6 (log Koc 2.57). In conclusion, the result obtained in the study using the HPLC method, which is used as key value for this endpoint, might overestimate the Koc, especially since only the main peak with the higher retention time was taken into consideration.