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Reference
Endpoint:
adsorption / desorption: screening
Type of information:
experimental study
Adequacy of study:
key study
Study period:
2010
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
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:
no
Qualifier:
according to guideline
Guideline:
EU Method C.19 (Estimation of the Adsorption Coefficient (KOC) on Soil and Sewage Sludge Using High Performance Liquid Chromatography (HPLC))
Deviations:
no
GLP compliance:
yes (incl. QA statement)
Type of method:
HPLC estimation method
Media:
other: HPLC column
Radiolabelling:
no
Test temperature:
Column temperature 35 ± 1 °C
Details on study design: HPLC method:
EQUIPMENT
- Apparatus: Alliance Separation Module 2695
- Type, material and dimension of analytical (guard) column: Hypersil BDS-CN, 150 mm ± 4.6 mm i.d., dp = 5 µm
- Detection system: Dual λ Absorbance Detector 2487

MOBILE PHASES
- Type: 55/45 (v/v) methanol/water
- pH: neutral
- Solutes for dissolving test and reference substances: methanol; The stock solutions were diluted to obtain an end solution of 55/45 (v/v) methanol/water.

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

REFERENCE SUBSTANCES
- Identity: Acetanilide, Atrazine, Monuron, 2,5-Dichloroaniline, Benzoic acid phenylester, Fenthion, Phenanthrene, 2,4-DDT


DETERMINATION OF RETENTION TIMES
- Quantity of test substance introduced in the column: 10 µl (7.7 µg)
- Quantity of reference substances: 10 µl (5.5 µg)

REPETITIONS
- Number of determinations: The reference substance and test substance solutions were injected in duplicate. Blank solutions were analysed by single injection.

EVALUATION
- Calculation of capacity factors k': k' = (tr - t0)/t0 where:
tr = retention time
t0 = mean column dead time

- Calculation of retention times: Taken from the HPLC chromatograms
- Determination of the log Koc value: log k' = a logKoc + b; where: a = slope, b = intercept
Analytical monitoring:
not required
Type:
Koc
Value:
330
Temp.:
35 °C
Remarks on result:
other: HPLC column temperature 35 °C
Type:
log Koc
Value:
2.52
Temp.:
35 °C
Remarks on result:
other: HPLC column temperature 35 °C
Details on results (HPLC method):
HPLC chromatograms of the test substance solution and corresponding blank solution are shown in Figure 1 (see below).
- Retention times of reference substances used for calibration: See Table 1 below
- Details of fitted regression line (log k' vs. log Koc): The equation of the regression line was: log k’ = 0.264 × log Koc – 1.214 (r = 0.97, n = 16).
- Graph of regression line attached: Figure 2 (see illustration below) shows the calibration curve of the log k’ of the reference substances as function of log Koc.
- Average retention data for test substance: See Table 1 below

Table 1: Kocof the test substance

Substance

tr,1
[min]

tr,2
[min]

mean tr
(n=2)

log Koc

Koc

Area
%

 

 

 

 

 

 

 

Formamide (t0)

1.961

1.960

1.961

 

 

 

 

 

 

 

 

 

 

Acetanilide

2.165

2.165

 

1.26

 

 

Atrazine

2.307

2.307

 

1.81

 

 

Monuron

2.351

2.350

 

1.99

 

 

2,5-Dichloroaniline

2.525

2.524

 

2.55

 

 

Benzoic acid phenylester

2.758

2.757

 

2.87

 

 

Fenthion

3.268

3.267

 

3.31

 

 

Phenanthrene

3.418

3.417

 

4.09

 

 

2,4-DDT

4.903

4.904

 

5.63

 

 

 

 

 

 

 

 

 

Impurity I

1.301

1.301

1.301

<1.26

<1.8x101

0.37

Test substance

2.518

2.517

2.518

2.52

3.3x102

98.7

Impurity II

2.804

2.804

2.804

3.21

1.6x103

0.91

 

 

 

 

 

 

 

 

Validity criteria fulfilled:
yes
Conclusions:
The log Koc of 2-ethylhexyl-S-lactate is 2.52.
Executive summary:

The HPLC method using soil-adsorption-reference data was chosen for the determination of the adsorption coefficient of PURASOLV®EHL (2-ethylhexyl-S-lactate).

The Kocand log Kocvalue of the test substance was:

 

neutral pH

 

Koc

log Koc

 

 

 

Test substance

3.3 × 10²

2.52

 

 

Description of key information

The log Koc of 2-ethylhexyl-S-lactate is 2.52.

Key value for chemical safety assessment

Koc at 20 °C:
330

Additional information

[LogKoc: 2.52]

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