Registration Dossier

Administrative data

Endpoint:
adsorption / desorption: screening
Type of information:
experimental study
Adequacy of study:
supporting study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
guideline study with acceptable restrictions

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2012
Report Date:
2012

Materials and methods

Test guideline
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
Remarks:
The study was conducted according to the guideline in effect at the time of study conduct.
GLP compliance:
yes
Type of method:
HPLC estimation method
Media:
soil/sewage sludge

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
- Purity: 22.82% solids in water
Radiolabelling:
no

Study design

Test temperature:
Column Temperature: 27 - 28 °C

HPLC method

Details on study design: HPLC method:
In each experiment six chemicals for which log Koc has been reported were used to calibrate the elution time in units of log Koc. Structurally heterogeneous reference items were chosen from the list stated in the guideline. The reference standards used included acetanilide, benzamide, atrazine, 1,2,3-trichlorobenzene, pyazophos, phenanthrene, DDT, and sodium nitrate. A solution of sodium nitrate was injected for determination of the dead time.
Each reference compound was dissolved in methanol (except sodium nitrate, which was dissolved in pure water) to prepare stock solutions of each. Calculated volumes of these stock solutions were diluted with methanol/pure water (1:1, v/v) to prepare 10 mg/L standard solutions of these compounds. Afterwards, defined volumes of each of the stock solutions were diluted with methanol/pure water (1:1, v/v) to prepare the reference item mix for the HPLC-measurements.
The test substance solution was prepared by dissolving the test substance in methanol/pure water (1:1, v/v) to obtain a solution of approximately 40 g test substance/L. The test solution with a concentration of approximately 40 g test item/L was used for the HPLC-measurements.
The reference items were injected separately and mixed. Their retention times were determined, permitting the calculation of the capacity factor k'. The reference item mix was injected before and after the test item. The test item was injected three times. For the determination of t0 (t0 = retention time of the unretarded component) sodium nitrate solution was also injected three times. The calibration curve was based on the retention time of reference items injected as a mixture, since it was confirmed that the retention of each reference substance was unaffected by the presence of the other reference substances.
The following instrument conditions were used:
Column: LiChrospher 100 CN (250 × 4 mm, 5 μm)
Mobile Phase: 55% methanol/ 45% 0.01 M citrate buffer solution at pH 6
Flow Rate: 0.5 mL/min
Detector: DAD Detector
Detection Wave Length: 200 to 400 nm (evaluation at 230 nm and 210 nm)
Temperature: 27 - 28°C
Injection Volume: 50 μL

The adsorption coefficient Koc wass deduced from the capacity factor k' using a calibration plot of log k' versus log Koc of selected reference items. The capacity factor was calculated from the retention of the substance concerned (tr) and the unretarded component (t0) using the following equation: k’ =(tr – t0)/t0
where:
tr = retention time of the test item [min]
t0 = time a non-sorbed chemical needs to pass the column (dead time) [min]
k' = capacity factor
The adsorption coefficient Koc of the test item was interpolated or extrapolated from the calibration curve which was established by correction of the log Koc of various reference items with their corresponding log k'-values. The correlation was performed using the function given below, obtained by regression analysis.
The log k'-value of the test item was compared with the log k'-values of the reference items with known log Koc values. Therefore the log Koc value x of the test item was calculated by the following equation:
y = m * x + b
where
y = log k'- k'
x = log Koc-value of the test item
m = slope
b = y-axis intercept

Results and discussion

Adsorption coefficientopen allclose all
Type:
log Koc
Value:
-3.8
Temp.:
27 °C
Remarks on result:
other: The test substance was resolved into three substance-related peaks by HPLC therefore a range of three log Koc values were determined.
Type:
log Koc
Value:
5.5
Temp.:
27 °C
Type:
log Koc
Value:
7.2
Temp.:
27 °C

Results: HPLC method

Details on results (HPLC method):
The test item was resolved into three substance-related peaks by HPLC therefore a range of three log Koc values were determined.
The logarithmic adsorption coefficients (log Koc) of the test item were estimated to be -3.8 (extrapolated), 5.5 and 7.2 (extrapolated) using the HPLC method at 27 - 28°C.
The linearity of the method was proved in the log Koc-range from 1.25 to 5.63.
Calibration Curve: y = 0.0912 * x - 0.2454, Regression Coefficient r² = 0.9484
Although reference substances were not available for the individual components contained in the test substance, it was anticipated that the lowest measured Koc can be attributed to lysine because it would not be retained by the column and the two higher Koc values can be attributed to phosphate esters of the fluorinated alcohols.

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Conclusions:
log Koc estimated to be -3.8 (extrapolated), 5.5 and 7.2 (extrapolated).
Executive summary:

The adsorption coefficient (Koc) of the test substance was determined using the HPLC method and UV detection. The test substance was resolved into three substance-related peaks by HPLC, therefore a range of three log Koc values were determined. The logarithmic adsorption coefficients (log Koc) of the test substance were estimated to be -3.8 (extrapolated), 5.5 and 7.2 (extrapolated) using the HPLC method at 27 - 28°C.