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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:
2011-10-05 to 2011-11-16
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
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))
Version / remarks:
adopted 2001
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))
Version / remarks:
adopted 2001
Deviations:
no
GLP compliance:
yes (incl. certificate)
Type of method:
HPLC estimation method
Media:
soil/sewage sludge
Details on study design: HPLC method:
EQUIPMENT
- Apparatus:
HPLC system 2: Merck-Hitachi LaChrom Elite
L-2000 Organizer, No.: 22E82-042
L-2130 HPLC pump, No.: 22E50-029
L-2200 Autosampler, No.: 22E81-005
L-2400 UV Detector, No.: 22E80-018
L-2350 Column Oven, No.: 2274-034
Balance: BL120S Sartorius, No.: 15307011
Ultrasonic bath: Branson 3210, No.: A700343D
Water purification system: MILLIPORE, DIRECT Q5,
No.: FODA13956K
- HPLC Conditions:
Column: LiChrospher 100 CN (5μm) 250x4, No: 933278
Mobile Phase: Acetonitrile : water =60 : 40 (v/v)
Flow: 0.8 mL/min
Injection volume: 10 μl
Temperature: 25 °C
Detector: 254 nm (Reference standards)
Detector: 210 nm (TBPND)

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

REFERENCE SUBSTANCES
- Identity: Sodium nitrate, Acetanilide, Methyl Benzoate, Naphthalene, Fenthion, Pyrazophos, Phenanthrene, DDT

DETERMINATION OF RETENTION TIMES
Three series of the above-mentioned reference solutions were measured with two parallel injections, each. Three series of the test item solution were measured with two parallel injections, each. The retention times were determined. The three calibration series and three test item series were measured alternately. For the determination of t0 (t0 = retention time of the unretarded component) three series of Sodium Nitrate solution were injected two times.

EVALUATION
Chromatograms were evaluated using EZChrom Elite chromatogram processor software. Calculations were carried out using Microsoft Office Excel.
The capacity factors, k were calculated from the retention times (tR) of the selected reference substances and the dead time (t0):
k = (tR-t0)/t0
Then the log k data of the reference substances were plotted against their log Koc values. The regression coefficients (a, b) were determined by linear
regression calculation using the least squares method. The log Koc value of the test item was calculated, using these regression coefficients and the capacity factor of the test item: log k = a + b*log Koc
where: Koc = adsorption coefficient; a = constant; b = slope; k = capacity factor


Key result
Type:
Koc
Value:
4 424
Temp.:
25 °C
Remarks on result:
other: Conf.int.(95%) 538
Key result
Type:
log Koc
Value:
3.64
Temp.:
25 °C
Remarks on result:
other: Conf.int.(95%) 0.052
Details on results (HPLC method):
- Retention times of reference substances used for calibration:
Naphthalene: 4.92 min
Fenthion: 5.30 min
Pyrazophos: 5.00 min
Phenantrene: 5.44 min
DDT: 7.07 min
- Details of fitted regression line (log k' vs. log Koc): The correlation coefficient R for the relationship between log k' and log Koc of the test substance is 0.949.
Validity criteria fulfilled:
yes
Conclusions:
The determined log Koc: 3.64 ± 0.052 (95 % confidence interval). The determined Koc: 4424 ±538 (95 % confidence interval).
Executive summary:

The purpose of this study was to estimate the adsorption coefficient, Koc of the test item using HPLC. This method is applicable for substances, which have log Koc value ranging from 1.5 to 5.0. The adorption coefficient was estimated to be 4424 and the log Koc was 3.64.

Description of key information

The adsorption coefficient of the test item was assessed according to OECD guideline 121 and EU-method C.19.The log Koc was determined to be 3.64.

Key value for chemical safety assessment

Koc at 20 °C:
4 424

Additional information

The Koc was measured using the HPLC method. This method is applicable for substances which have log Koc value ranging from 1.5 to 5.0. The adorption coefficient was estimated to be 4424 and the log Koc was 3.64.

[LogKoc: 3.64]