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Environmental fate & pathways

Adsorption / desorption

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Reference
Endpoint:
adsorption / desorption: screening
Type of information:
experimental study
Adequacy of study:
key study
Study period:
2013
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
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
Qualifier:
equivalent or similar 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
GLP compliance:
yes (incl. QA statement)
Type of method:
HPLC estimation method
Media:
soil/sewage sludge
Radiolabelling:
no
Test temperature:
In order to ensure a stable performance of the HPLC column, the column temperature was set to 40 °C. The reference Koc-values in the OECD guideline presumably refer to 25 °C. Even though the column temperature was 40 °C, this temperature has no influence on the result of the determination. Therefore the Koc-value of the test item determined within this study also refers to 25 °C.
Details on study design: HPLC method:
Chromatograph: High Performance Liquid Chromatograph, Agilent 1100
Chromatographic conditions:
- Column type: length: 250 mm, inner diameter: 4 mm
- Stationary Phase: LiChrospher 100 CN, particle diameter: 5 μm
- Supplier: Fa. Merck
- Mobile Phase: A: 832 ml demineralized water (Millipore) + 168 mL buffer pH 6 (Fluka, Art. No. 33545); B: Acetonitrile
- isocratic 45 % A, 55 %B
- Flow rate: 1.0 mL / minute
- Column Temperature: 40 °C
- Injection volume: 5 μl
- Detection: UV, 220 nm
Computational methods:
The log Koc value was calculated with the software PCKOCWIN v1.66 assuming the nonionic form. PCKOCWIN is owned by the U.S. Environmental Protection Agency.
For the substance, the calculated adsorption coefficient is: log Koc = 6.1.
Type:
log Koc
Value:
7.3
Temp.:
25 °C
Details on results (HPLC method):
The chromatogram of the test item Bis(2-ethylhexyl) tetrabromophthalate showed 1 signal eluting at 5.2 minutes for the main component and 1 signals eluting at 4.3 minutes for a minor component. No calibration substance with a Koc-value above the value for the main signal of the test item Bis(2-ethylhexyl) tetrabromophthalate was available. For this reason the results for this signal was extrapolated

Determination of the Adsorption Coefficient (Koc). Mean of 3 single values.

 Calibration item  Retention time [tr] = (min)  Standard deviation of the retention time [tr] (min)  Relative standard deviation%  Capacity factor k'  Log k'  log Koc
 Sodium nitrate(dead time (t0))  1.660  0.001  0.060  -  -  -
 2 -Nitrobenzamide  2.683  0.002  0.078  0.616  -0.210  1.45
 3,5 -Dinitrobenzamide 2.780  0.003  0.095  0.675  -0.171  2.31
 Triazoxide  3.209  0.003  0.095  0.933  -0.030  2.44
 1,2,3 -Trichlorobenzene  3.334  0.005  0.137  1.009  0.004  3.16
 Phenanthrene  3.501  0.005  0.135  1.109  0.045  4.09
 9,10-Dimethyl-1,2-benz-anthracene 3.923 0.007 0.188  1.363  0.135 5.37 
 Test item   5.179   0.0141   0.27  2.120  0.3267 7.34 
Validity criteria fulfilled:
yes
Remarks:
Although the determined value does not exactly meet the range of application of the test guideline (1.45 – 3.16), we consider the value as valid (measurement uncertainty +/- 0.5 log units).
Conclusions:
The adsorption coefficient of the substance determined by HPLC was log Koc = 7.3 at 25°C.
Executive summary:

The adsorption coefficient (Koc) of the substance was determined according to the HPLC method at 40 °C. In order to comply with the guideline OECD 121 and considering environmental relevance, pH 6 was chosen as pH value for the buffer. The reference Koc-values in the OECD-guideline presumably refer to 25 °C. Even though the column temperature was 40 °C, this temperature is without influence on the result of the determination. The calibration was done referring to Koc- values of reference substances determined at 25 °C.

The adsorption coefficient of the substance determined by HPLC was log Koc = 7.3.

Description of key information

The adsorption coefficient of the substance determined by HPLC was log Koc = 7.3 at 25°C. This value indicates a very strong sorption to soil and sediment and a negligible migration potential to groundwater.

Key value for chemical safety assessment

Koc at 20 °C:
19 952 623

Additional information

should read: "log Koc = 7.3 at 25°C"

The adsorption coefficient (Koc) of the substance was determined according to the HPLC method at 40 °C. In order to comply with the guideline OECD 121 and considering environmental relevance, pH 6 was chosen as pH value for the buffer. The reference Koc-values in the OECD-guideline presumably refer to 25 °C. Even though the column temperature was 40 °C, this temperature is without influence on the result of the determination. The calibration was done referring to Koc- values of reference substances determined at 25 °C.

[LogKoc: 7.3]