Di(benzothiazol-2-yl) disulphide

Water solubility

Link to relevant study record(s)

Reference

Endpoint:

water solubility

Type of information:

experimental study

Adequacy of study:

key study

Study period:

May 2015 - June 2015

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 105 (Water Solubility)

GLP compliance:

yes (incl. QA statement)

Type of method:

flask method

Water solubility:

< 0.05 mg/L

Conc. based on:

test mat.

Temp.:

20 °C

pH:

5

Details on results:

The results represents the mean value taken from four measurements.

Conclusions:

The water solubilty of MBTS was determined to be <0.05 mg/L.

Executive summary:

The water solubility of Rubator MBTS in demineralized water was investigated by the flask method according to guideline OECD 105. A value of the water solubility was determined via HPLC to be <0.05 mg/L at 20°C at a pH = 5 (Currenta 2015).

Description of key information

MBTS is expected to be insoluble in water at pH 7 due to big molecule and

negligible dissociation constant. Indeed, an experimental study performing the flask method in combination with HPLC analytics according to OECD guideline 105 showed a poor water solubility of <0.05 mg/L at 20 °C and a pH = 5 (Currenta, 2015). The manufacture information from Bayer (1993) , Lanxess (2007) and General Quimica (2007) further support this very low value with a water solubility of MBTS smaller than 0.2 mg/l at 20°C.

Key value for chemical safety assessment

Water solubility:

0.05 mg/L

at the temperature of:

20 °C

Additional information

The experimentally confirmed poor water solubility of MBTS of <0.05 mg/L at 20 °C (Currenta 2015) is further supported by the information from other resources, such as:

- estimated value of 0.27- 0.37 mg/L at 25°C and pH = 7 using WSKOW, v. 1.41 (Currenta, 2010)

- expert judgment according to rather big molecule and negligible dissociation constant at environmentally relevant pH (i.e. pH of 5-9): insoluble at pH 7 and room temperature

- peer-reviewed literatures: Merck Index (2009) and NIOSH (1997) reported MBTS as insoluble

- observations from ecotoxicity studies: precipitation and cloudiness in test solutions of MBTS in water and actual concentrations below detection limit (<0.3 mg/L).

In contrast, Monsanto (1980) using column elution method reported a water solubility of MBTS in the range of 49-88 mg/L at 22°C. This result does not match with information from any other resources and considered as doubtful according to expert judgment; and hence will not be taken into account for further assessment.