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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:
2016
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
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:
2001
Deviations:
no
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:
2008
Deviations:
no
GLP compliance:
yes (incl. certificate)
Type of method:
HPLC estimation method
Media:
soil/sewage sludge
Radiolabelling:
no
Details on study design: HPLC method:
Apparatus
Shimadzu UFLC:
SIL-20ACHT UFLC Autosampler
CTO-20AC Column Oven
LC-20AD Pump A
DGU-20A 3R Degassing Unit
CBM-20A System Controller
SPD-20A UV/VIS Detector

HPLC Conditions (Method 1)
Detector:
254 nm (Reference Items)
270 nm (Test Item)
Column: LiChrospher 100 CN (5μm) 250-4
Temperature: 25 °C
Mobil Phase: Methanol : Water = 55 : 45 (v/v)
Flow Rate: 1 mL/min
Injection volume: 5 μL

HPLC Conditions (Method 2)
Detector:
254 nm (Reference Items)
270 nm (Test Item)
Column: LiChrospher 100 CN (5μm) 250-4
Temperature: 25 °C
Mobil Phase: Methanol : 0.1 M citrate-buffer, pH 3.0 = 55 : 45 (v/v)
Flow Rate: 1 mL/min
Injection volume: 5 μL

HPLC Conditions (Method 3)
Detector:
254 nm (Reference Items)
270 nm (Test Item)
Column: LiChrospher 100 CN (5μm) 250-4
Temperature: 25 °C
Mobil Phase: Methanol : 0.1 M citrate-buffer, pH 6.1 = 55 : 45 (v/v)
Flow Rate: 1 mL/min
Injection volume: 5 μL


DETERMINATION OF DEAD TIME
Three series of sodium nitrate solution were injected.

REFERENCE SUBSTANCES
Reference substance CAS No. log Koc
Sodium nitrate 7631-99-4 -
Acetanilide 103-84-4 1.25
Methyl Benzoate 93-58-3 1.80
Linuron 330-55-2 2.59
Naphthalene 91-20-3 2.75
Pyrazophos 13457-18-6 3.65
Phenanthrene 85-01-8 4.09
DDT 50-29-3 5.63

DETERMINATION OF RETENTION TIMES
Chromatograms were evaluated using EZChrom Elite chromatogram processor software.

REPETITIONS
Three series of the above-mentioned reference solutions and the test item solution were measured. The retention times were determined.

EVALUATION
The capacity factors, k were calculated from the retention times (tR) of the selected reference items and the dead time (t0). Then the log k data of the reference items were plotted against their log Koc values.
Key result
Sample No.:
#1
Type:
log Koc
Value:
< 1.5 dimensionless
Temp.:
25 °C
Key result
Sample No.:
#2
Type:
log Koc
Value:
< 1.5 dimensionless
Temp.:
25 °C
Key result
Sample No.:
#3
Type:
log Koc
Value:
< 1.5 dimensionless
Temp.:
25 °C
Details on results (HPLC method):
Retention times measured for 7-ACA (1.28 minutes (Method 1), 2.63 minutes (Method 2) and 2.58 minutes (Method 3)) are lower than the retention time of the first eluting standard Acetanilide (3.33 minutes (Method 1), 3.31 minutes (Method 2) and 3.34 (Method 3)). This result shows that log Koc of 7-ACA is lower than the calibrated range. As the Acetanilide is the reference item with lowest Koc value, no further test was performed.
Using the HPLC method the log Koc of 7-ACA was determined to be < 1.5.
Quality criteria were met, as values of log Koc derived from individual measurements fell within a range of 0.25 log units.
The correlation coefficient R square for the relationship between log k and log Koc of the reference item was 0.990 (Method 1), 0.966 (Method 2) and 0.967 (Method 3).
The difference of the estimated log Koc to the known value of reference item fell within a range of ± 0.5 log units.
Validity criteria fulfilled:
yes
Conclusions:
The log Koc of 7-ACA was determined to <1.5.
Executive summary:

Using the HPLC method, the log Koc of 7-ACA was determined to <1.5.

Description of key information

Key value for chemical safety assessment

Koc at 20 °C:
1.5

Additional information

The Koc is not 1.5 but is <1.5, which can not be entered in the field above.

[LogKoc: 0.176]

[LogKoc: 0.176]