Di-tert-dodecyl 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:

October 2015-January 2016

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 105 (Water Solubility)

Version / remarks:

Slow-stirring flask method

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Type of method:

flask method

Key result

Water solubility:

0 g/L

Conc. based on:

test mat.

Loading of aqueous phase:

770 other: µL/L

Incubation duration:

72 h

Temp.:

20 °C

pH:

7.3

Details on results:

Three containers were filled with 1000 ml double distilled water. A volume of 770 µl of the test item was added to the glass vessels avoiding turbulent mixing of the two phases. The closed vessels were placed on a magnetic stirring device at 19.7 +/- 0.4°C where the content of each vessel was gently stirred at 100 rpm for 24, 48 or 72 hours. As the blank, 1000 ml double distilled water was stirred for 72 hours.
After the stirring period, subsamples of the water phase were taken directly from the bottom of the container avoiding sampling of undissolved test item.
SPE cartridges were pre conditioned with 10 ml dichloromethane followed by 10 ml iso-propanol and 10 ml water. Care was taken not to let the cartridges run dry. 200 ml of the aqueous phases were sampled through the SPE cartridges slowly for approximately 45 minutes. After elution, the cartridges were dried using a vacuum pump. The cartridges were considered dry when the yellow SPE material completely turned white. The test item was eluted from the SPE cartridges with 20 ml
dichloromethane, which was firstly used to clean the volumetric flask out of which the 200 ml aqueous phases were sampled. The eluates were collected in 20 ml volumetric flasks and the flasks were filled to the mark with dichloromethane. If necessary, the samples were further diluted with dichloromethane to obtain concentrations within the calibration range.
The pH of each of the water mixtures (except for the blank) was determined. The samples were diluted in a 9:1 (v:v) ratio with 0.1 M sodium chloride in order to obtain a high electrolyte concentration for accurate pH measurement. The sodium chloride solution contained 0.0009% (w/v) sodium azide.
Remark : the maximum difference (MD) of the concentrations determined in the 24, 48 and 72 hour test samples was > 15%. The MD was still much higher than 15% due to extremely low water solubility and minimal contamination with small test item droplet. In Guidance on information requirements and Chemical Safety Assessment Chapter R.7a: Endpoint specific guidance says for sparingly soluble test items (ppb-ppm): “Reported water solubility data for such compounds can often contain appreciable errors.” Since the 48 hour value likely results from a droplet contamination, the water solubility of the test item is given as the mean value of the analysed concentrations after 24 and 72 hours and high MD was accepted.

Main study - water solubility of the test item

Stirring time [hours]	Analysed concentration [g/l]	Mean (24 and 72 h) [g/l]	MD [%]	pH
24	3.04 x 10-7			7.3
48	3.54 x 10-6	2.60 ¿ 10-7	34	7.3
72	2.15 x 10-7			7.3

Since the 48 hour value likely results from a droplet contamination, the water solubility of the test item is given as the mean value of the analysed concentrations after 24 and 72 hours and high MD was accepted.

Conclusions:

The water solubility of the test item at 20°C was 2.60 x 10-7 g/l (i.e. 0.260 µg/l).

Executive summary:

The slow-stirring flask method was applied for the determination of the water solubility of TPS 32 (polysulfides, di-tert-dodecyl).

Analysis of the test item was made according to an UPLC-MS/MS specific method making use of derivatization with AgBF4.

The water solubility of the test item at 20°C was found to be 2.60 x 10-7 g/l (i.e. 0.260 µg/l).

The pH of the aqueous samples was 7.3.

Description of key information

The water solubility of di-tert-dodecyl polysulfides has been measured according to OECD 105 (slow-stirring flask method). Solubility was 0.26 µg/L. The solubility of di-tert-dodecyl disulfide was below the limit of detection (< 30µg/L). The solubility of di-tert-dodecyl disulfide is considered equal to 0.26 µg/L.

See section "Additional information".

Key value for chemical safety assessment

Water solubility:

0.26 µg/L

at the temperature of:

20 °C

Additional information

A read-across approach was developped to demonstrate that the substance is likely to be comparable or less water soluble than the source substance thereby confirming that the data derived with di-tert-dodecyl polysulfide can be considered adequate.

Table 3b: Comparaison of Log Kow and water solubility issued from QSAR for di-tert-dodecyl polysulfides, di- tert-dodecyl disulfide, dodecyl disulfide and di-tert-nonyl polysulfide

 

Substance name	CAS number	MW g/mol	Log Kow (Kowwin)	Water solubility (WsKowwin)	Water solubility (WaterNT v1.01)
dodecyl disulfide	10496-18-1	346.7	10.7	4.6 µg/L	2.3 µg/L
di-tert-nonyl polysulfide	38622-35-4	414.8	9.14	38.8 µg/L	1.7 µg/L
di-tert-dodecyl polysulfide	68425-15-0	434.9	12.5	0.043 µg/L	0.43 µg/L
Di-tert-dodecyl disulphide	27458-90-8	402.8	12.5	0.068 µg/L	0.40 µg/L