Molybdenum sulfide

Water solubility

Link to relevant study record(s)

Reference

Endpoint:

water solubility

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 105 (Water Solubility)

Version / remarks:

adopted 27 July 1995

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Type of method:

flask method

Water solubility:

<= 200 µg/L

Temp.:

20 °C

pH:

5

Details on results:

ICP-MS measurement and determination of water solubility
Molybdenum concentrations between 14.4 and 1123 µg/L were measured in the various samples. High concentrations in one of the duplicates seen at 96, 168 and 192 hours were assumed to be a result of very fine, undissolved particles passing through the filter. Thus, they were not considered for the test evaluation. Based on all other results and under consideration of the fact that no clear trend or saturation could be observed, it is concluded that the actual measured molybdenum concentrations after 8 days under the applied test conditions are below 100 µg/L. Based on the stoichiometry of the test item molybdenum disulfide, which contains 59.9% (mass) of molybdenum, approximately 167 µg MoS2 need to dissolve in 1 L to yield molybdenum concentrations of 100 µg/L. This figure was rounded to 200 µg/L.
The water temperature had a standard deviation of +/- 0.5.
Observations:
During the study a dark grey/silver precipitate of molybdenum disulfide has been observed. After filtration of the solution with a syringe filter (porosity 0.45 µm) the solution was clear and without colour. The temperature of the water batch was held at 20.0 +/- 1.0 °C. No further observations have been made.

Conclusions:

Interpretation of results: practically insoluble
Under the conditions of these test, water solubility of molybdenum disulfide in distilled water at 20 +/- 0.5 °C after 8 days is determined as < 200 µg/L, which is considered practically insoluble.

Description of key information

In an experimental water solubility study (acc. OECD 105 method) MoS₂ was agitated in pure water for 8 days at a loading of 1 g / 500 mL. Dissolved molybdenum concentrations are below 100 µg/L, confirming that MoS₂ is practically insoluble (solubility well below 200 µg MoS₂/L).

In addition to the standard OECD TG 105 water solubility study, the substance has also been tested in a bioelution study (in vitro bioaccessibility) in artificial gastric juice. This test and the results are described in the stand-alone document „MoCon read-across concept (human health)“, which is attached to the technical dossier in IUCLID section 13.