Fatty acids, tall-oil, polymers with glycidyl neodecanoate

Adsorption / desorption

Link to relevant study record(s)

Reference

Endpoint:

adsorption / desorption: screening

Type of information:

experimental study

Adequacy of study:

key study

Study period:

From September 12, 2016 to January 30, 2017

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:

sewage sludge

Radiolabelling:

no

Details on study design: HPLC method:

EQUIPMENT
HPLC_MS
Pump: HGP-3400SD
Autosampler: WPS-3000SL
Coulmn Oven: TCC-3000SD with 6 fold motor switch valve
UV-Detector: VWD-3400RS
Software: CHROMELEON 6.80 SR8 Build 2623
Manufacturer: Dionex

Flow rate 0.8 mL/min
Injection volume 20 μL
Column: Reprosil Pur CN, 125*4.6 mm with
precolumn Phenomenex Security Guard CN, 4*3 mm
Column temperature 25 ± 0.5 °C.
Wavelenght for evaluation 230 nm

MOBILE PHASES
A mixture of 55% methanol/ and 45% water, isocratic, was used for 16 min, following by linear increase to 100 % methanol over 1 min. 100 % methanol was held for 4 min, then initial conditions were restored for the next sample. The mixture methanol/water, 55/45 %
(v/v), was produced by mixing 275 mL methanol and 225 mL water. pH of the eluent was 6 – 7(tested with pH paper).

DETERMINATION OF DEAD TIME
The dead time t0 was measured by using an unretained compound (sodium nitrate) which was included in the mix of the reference items.

REFERENCE SUBSTANCES
- Identity:
Sodium nitrate
Phenol
Methylbenzoate
Naphthalene
1,2,3-Trichlorobenzene
Phenanthrene
DDT


DETERMINATION OF RETENTION TIMES
- Quantity of test substance introduced in the column:
- Quantity of reference substances:
- Intervals of calibration:


EVALUATION
- Determination of the log Koc value: One vial was filled with the reference item mix and one vial with the test item solution. The vials were analysed using HPLC with the program described above. Three injections were measured from the reference item mix, three injections from the test item solution and again three injections from the reference item mix.
The data was saved, the retention times of the seven peaks of the reference item mix and the retention time of the peaks of the test item were used for further calculations.

Key result

Type:

log Koc

Value:

> 5.63

Details on results (HPLC method):

In the main test the test item peak showed two peaks, a small peak with a retention time of 8.02 minutes and a large peak with a retention time of 19.53 minutes.
Variations in the retention times of reference items and test item are very small. Therefore a stable configuration of the HPLC-column can be assumed.
The correlation log k’/log KOC is sufficiently accurate, as calibration gave a coefficient of determination r2 = 0.9984.
The chromatogram of the main test showed two peaks that are linked to the test item: a small peak with a retention time of 8.02 minutes and a large peak with a retention time of 19.53 minutes.
As Peak 1 showed a relative area < 5%, it was considered as a minor peak. The calculation of the log KOC of Peak 2 was not possible because this constituent of the test item eluted outside the isocratic part of the HPLC program. Extrapolation is therefore not possible. Because the retention time of Peak 2 is higher than the retention time of DDT (10.976 min) the log KOC corresponding to Peak 2 is stated as > 5.63 (log KOC of DDT).
Although area is not necessarily correlated to absolute concentration if a UV detector is used, it is believed that the test item consists mainly of the second peak, indicating that the log KOC should be stated as > 5.63.
No observations were made which might give doubts concerning the validity of the study outcome.

Validity criteria fulfilled:

yes

Conclusions:

Under the study conditions, the log Koc of the test substance is considered to be > 5.63.

Executive summary:

A study was conducted to determine the adsorption coefficient of the test substance on soil and sewage sludge according to OECD Guideline 121 and EU Method C.19, in compliance with GLP. The study was performed using HPLC with a cyanopropyl chemical-bound resin on a silica base column. Six reference substances with different retention times were used to produce a calibration curve, since retention time on cyanopropyl columns and Koc are correlated. The reference substances were chosen based on the retention time of the test substance resulting from the pre-test. A solvent blank followed by three injections of a solution of the reference substances were analysed with HPLC, then three injections of a solution of the test substance; and finally three injections of the solution with the reference substances, totalling to ten runs. For each reference substance, the capacity factor k’ was calculated from the retention time of sodium nitrate (not retained and thus representing the dead time) and the retention time of the respective reference substance. A calibration function was set up using the literature values for Koc of the reference substances and the mean capacity factor of the six determinations. In the graph log k’ versus log Koc, linear regression was performed, giving r2 = 0.9984 and r = 0.9992. The chromatogram of the main test showed two peaks that are linked to the test substance: a small peak with a retention time of 8.02 min and a large peak with a retention time of 19.53 min. As Peak 1 showed a relative area < 5%, it was considered as a minor peak. The calculation of the log Koc of Peak 2 was not possible because the peak eluted outside the isocratic part of the HPLC program. Extrapolation is therefore not possible. Because the retention time of Peak 2 was higher than the retention time of DDT (10.976 min), the log Koc corresponding to Peak 2 was stated as> 5.63(log Koc of DDT). Although area is not necessarily correlated to absolute concentration if a UV detector is used, it is believed that the test substance consists mainly of the second peak, suggesting that the log Koc should be stated as> 5.63(Feierabend, 2017).

Key value for chemical safety assessment

Koc at 20 °C:

430 000

Additional information

A study was conducted to determine the adsorption coefficient of the test substance on soil and sewage sludge according to OECD Guideline 121 and EU Method C.19, in compliance with GLP. The study was performed using HPLC with a cyanopropyl chemical-bound resin on a silica base column. Six reference substances with different retention times were used to produce a calibration curve, since retention time on cyanopropyl columns and Koc are correlated. The reference substances were chosen based on the retention time of the test substance resulting from the pre-test. A solvent blank followed by three injections of a solution of the reference substances were analysed with HPLC, then three injections of a solution of the test substance; and finally three injections of the solution with the reference substances, totalling to ten runs. For each reference substance, the capacity factor k’ was calculated from the retention time of sodium nitrate (not retained and thus representing the dead time) and the retention time of the respective reference substance. A calibration function was set up using the literature values for Koc of the reference substances and the mean capacity factor of the six determinations. In the graph log k’ versus log Koc, linear regression was performed, giving r2 = 0.9984 and r = 0.9992. The chromatogram of the main test showed two peaks that are linked to the test substance: a small peak with a retention time of 8.02 min and a large peak with a retention time of 19.53 min. As Peak 1 showed a relative area < 5%, it was considered as a minor peak. The calculation of the log Koc of Peak 2 was not possible because the peak eluted outside the isocratic part of the HPLC program. Extrapolation is therefore not possible. Because the retention time of Peak 2 was higher than the retention time of DDT (10.976 min), the log Koc corresponding to Peak 2 was stated as > 5.63 (log Koc of DDT). Although area is not necessarily correlated to absolute concentration if a UV detector is used, it is believed that the test substance consists mainly of the second peak, suggesting that the log Koc should be stated as > 5.63 (Feierabend, 2017).

[LogKoc: 5.63]