Registration Dossier

Administrative data

Endpoint:
water solubility
Type of information:
experimental study
Adequacy of study:
key study
Study period:
From 25 SEPTEMBER 2019 to 13 JAN 2020
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study

Data source

Reference
Title:
Unnamed
Year:
2020
Report Date:
2020

Materials and methods

Test guidelineopen allclose all
Qualifier:
according to
Guideline:
OECD Guideline 105 (Water Solubility)
Version / remarks:
OECD Guidelines for the Testing of Chemicals; Method No. 105, adopted 27. jul 1995: "Water Solubility"
Deviations:
yes
Remarks:
2 minor deviations that were assessed by the study director: 1 deviation from the study plan and other from the guideline. These deviations were assessed by the Study Director as uncritical.
Qualifier:
according to
Guideline:
EU Method A.6 (Water Solubility)
Version / remarks:
Commission Regulation (EU) No 260/2014 amending Regulation (EC) No
440/2008: Method A.6: “Water solubility, adopted 24 January 2014.
Deviations:
yes
Remarks:
Demineralised water with TOC < 1 ppm and conductivity below 0.1 µS/cm was used (commercially available doubly distilled water guarantees a conductivity as large as 5 µS/cm).
GLP compliance:
yes (incl. certificate)
Type of method:
column elution method

Test material

Reference
Name:
Unnamed
Type:
Constituent
Test material form:
solid: particulate/powder

Results and discussion

Water solubility
Key result
Water solubility:
< 12.27 µg/L
Conc. based on:
test mat.
Loading of aqueous phase:
15.65 mg/L
Incubation duration:
ca. 22 h
Temp.:
20 °C
pH:
>= 6
Remarks on result:
other: The pH value of the samples was not determined as all samples showed a Tyndall effect.
Details on results:
As described in chapter 7.2.3, all collected samples showed a Tyndall effect. Therefore,
the samples collected with flow rate 1 were measured filtrated using PTFE membrane filters (0.45 µm) and unfiltrated to be able to estimate the water solubility of the test item.
Results are given in the following table. Due to an error, sample 1 of flow rate 1 was not
measured.
The filtrated samples showed solubility values of 12.27 – 15.65 mg/L, i.e. values that lay
(slightly) above the calibrated range. It is possible that these values originate from dissolved test item particles or that the test item only dissolved during elution with acetonitrile.
All solutions exhibited a Tyndall effect that was removed by filtration of the samples. After
filtration, the measured concentration of the test item in the samples lay below the LOQ of
the method, i.e. the lowest calibration level 2 µg/L. Thus, the solubility of the test item in
demineralised water either was below 2 µg/L or the test item completely adsorbed on the
filter material.

Applicant's summary and conclusion

Conclusions:
The test item shows the solubility < 12.27 µg/L , so could be considered as insoluble.
Executive summary:

Determination of the water solubility of the test item using the column elution method was performed twice as all collected samples showed a Tyndall effect. Therefore, the determination of the water solubility of the test item was repeated to exclude a preparation error during loading of the column. Only the results of the second performance are reported here. During the second performance, all collected samples showed a Tyndall effect again.
The determination was performed with two different flow rates (0.42 mL/min and
0.21 mL/min), but the Tyndall effect occurred independently from the flow rate.
The collected samples of flow rate 1 were filtrated using PTFE membrane filters to remove undissolved particles. After filtration, no more Tyndall effect was observed. The samples were measured filtrated and unfiltrated. In the filtrated samples, the concentration of the test item was below the LOQ of the method (2 µg/L). These results point to a very low solubility of the test item of < 2 µg/L or can be a result of adsorption of the test item on the filter material.
The concentration of the test item in the unfiltrated samples lay slightly above the calibrated range (12.27 – 15.65 mg/L). These values can arise from dissolved test item or be a result of the acetonitrile (contained in the eluent) dissolving the test item particles upon elution.
In conclusion, it can be stated that the determination of the water solubility of the test item is technically not possible because no clear test item solutions can be obtained.
However, solubility is considered to be
< 12.27 µg/L because the collected fractions containing this test item concentration showed turbidity.
No observations arousing doubts concerning the accuracy of the results and the validity of the study were made.