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Physical & Chemical properties

Water solubility

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Endpoint:
water solubility
Type of information:
experimental study
Adequacy of study:
supporting study
Reliability:
3 (not reliable)
Rationale for reliability incl. deficiencies:
significant methodological deficiencies
Remarks:
Although the test was performed according to OCED Guideline 105, and in line with GLP, the analytical methods employed are not able to detect the test substance with its associated ligand. Although the conclusion deeming the test material soluble is inaccurate, the test supports the decomposition of the test material in contact with water. The method of analysis involved derivatisation. This method only measures the amount of the alkyltin moiety, MBT, present and does not identify the other ligands attached to the tin. Currently there is no analytical method available that can quantify the actual named substance i.e. the entire organotin compound with its associated chloride ligand. All MBT measured was attributed to the named substance, MBTC. At pH 7.0 the derivatisation method of analysis gave inconsistent results, which may be related to the presence of the phosphate buffer and its effects on the derivatisation procedure. However, MBT was detected at over 50% after 5 days, so it is not likely that the MBT moiety is degrading in the solution. At pH 9.0 a 37% loss of MBT in solution was measured and a fine precipitate was observed in the solution. It is believed that this fine precipitate is the MBT oxide (MBTO), which accounts for the decrease in MBT levels in solution. The conclusion is that MBTC hydrolyses rapidly to MBT hydroxide, and the hydroxide remains in solution for a short period, depending on pH, but does eventually precipitate as MBTO. At environmental concentrations, any back reaction from a hydroxide to reform MBTC is not dominant.
Qualifier:
according to
Guideline:
OECD Guideline 105 (Water Solubility)
Qualifier:
equivalent or similar to
Guideline:
EU Method A.6 (Water Solubility)
Qualifier:
equivalent or similar to
Guideline:
EPA OPPTS 830.7840 (Water Solubility)
GLP compliance:
yes
Type of method:
flask method
Key result
Remarks on result:
other: The test material was soluble in water at all ratios

The analysed concentrations found in the solutions correspond with the weighed amount of test material. From all results it can be concluded that the test material is soluble in water in all ratios.

Conclusions:
Under the conditions of this study, the test material is completely soluble in water
Executive summary:

At the request of the ORTEP Association Stabiliser Task Force, TNO has determined the water solubility of the test material according to OCED Guideline 105. This procedure is equivalent to EC Directive 92/69/EEC Test A6 and US EPA OPPTS 830.7840 adopted August 1996.

Weighed and analysed amount of the test material:

0.1695g weighed - 0.161g analysed

0.3412g weighed - 0.317g analysed

0.1691g weighed - 0.158g analysed

Under the conditions of this study, the test material is completely soluble in water

Endpoint:
water solubility
Data waiving:
study technically not feasible
Justification for data waiving:
other:
Endpoint:
water solubility
Type of information:
not specified
Adequacy of study:
supporting study
Reliability:
4 (not assignable)
Rationale for reliability incl. deficiencies:
other: Value obtained from government report; specifics of test not reported.
Principles of method if other than guideline:
Data reported as short abstracts
GLP compliance:
not specified
Type of method:
other: not reported
Key result
Water solubility:
8.2 mg/L
Conclusions:
The test material was reported as being slightly water soluble, with solubility of 8.2 mg/L.
Executive summary:

The KEMI report stated the water solubility of the test material to be 8.2 mg/L.

Description of key information

In accordance with Annex XI section 2 of the Regulation EC 1907/2006, testing for a specific endpoint may be omitted, if it is technically not possible to conduct the study as a consequence of the properties of the test material. The test material also meets the specific rules for adaptation set out in column 2 section 7.7 of Annex VII where the test material is assumed to rapidly decompose in contact with water; further to this, the test material is believed to be highly insoluble in water and it is not possibly to analyse the test material with any technique at low levels on the basis of this property.  The following statement was included in a physico-chemical properties study by Baltussen (2010) concerning the feasibility of a water solubility study on the test material: β€œThe test material rapidly decomposes in contact with water forming a range of breakdown products. The test material can only be analysed after derivatisation, but using derivatisation, a distinction between intact test material and breakdown products can no longer be made. It is not possible to specifically analyse the intact test material with any technique at low levels which is required due to the expected low water solubility of the test material.”  It is considered not technically feasible to perform a water solubility test on the test material.  Reference: Baltussen E (2010) Determination of Physico-Chemical Properties of Monobutyltin Trichloride. NOTOX project no. 492798

Until very recently, the substance was considered to exhibit properties such that a waiver has been submitted to address this end point based on data to suggest the substance rapidly hydrolysed. This is no longer believed to be the case and new information now indicates the substancemay in fact behave differently than originally thought. A new water solubility study is therefore to be attempted to try and obtain a definitive result. The study is expected to be finished second quarter 2019 and the registration is proposed to be updated to take account of this information in late secoond quarter/ third quarter 2019.

Key value for chemical safety assessment

Water solubility:
1 mg/L
at the temperature of:
20 °C

Additional information

- The KEMI report stated the water solubility of the test material to be 8.2 mg/L.

A key value of 1 mg/l has been used for the chemical safety assessment.