Reaction Mass of 3,3-diphenylhexamethyltrisiloxane and 3,3,5,5-tetraphenylhexamethyltetrasiloxane

Water solubility

Link to relevant study record(s)

Reference

Endpoint:

water solubility

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2004-07-06 to 2004-07-17

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 105 (Water Solubility)

Version / remarks:

July 27 1995

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method A.6 (Water Solubility)

Version / remarks:

December 1992

Deviations:

no

GLP compliance:

yes

Type of method:

column elution method

Key result

Water solubility:

< 0.523 mg/L

Temp.:

20 °C

pH:

> 6.35 - ca. 7.29

Remarks on result:

other: The water solubility was determined to be below the limit of detection

Details on results:

During the preliminary test, the water solubility of the test substance at room temperature was estimated by a simplified flask method to be <1.2264 µg/mL. Therefore, the column elution method was used for the performance of the main test.

During the main test, six samples have been analysed in the first run (0.52 mL/min) and six samples during the second run (0.26 mL/min), each with a sampling interval of one hour. Total elution time was 74 hours. The sample measurement was performed by GC. The measured results differ by less than 30%. Therefore, the study is considered to be valid. The test item could not be detected in any of the eluate samples.

The chromatogram of the smallest calibration point of 0.2617 µg/mL is given in Figure 1 (attached) and a typical chromatogram of a test solution (eluate) is shown in Figure 2 (attached).

In conclusion, the water solubility of the test substance at 20°C was determined to be below the limit of detection which is <0.5234 mg/L using the column elution method.

Table 1: Results of the water solubility of the test item

Experiment No.	Flow rate [mL/h]	Sample No.	Concentration analysed [µg/mL]	Water solubility calculated [mg/L]	pH
1	31	1 2 3 4 5 6	<0.5234 <0.5234 <0.5234 <0.5234 <0.5234 <0.5234	<0.5234	6.78 6.62 6.64 7.29 6.79 6.46
2	16	7 8 9 10 11 12	<0.5234 <0.5234 <0.5234 <0.5234 <0.5234 <0.5234		6.35 6.73 6.57 6.52 6.40 6.37

 

 

Conclusions:

A water solubility value of <0.5234 mg/L at 20°C and pH 6.35 to 7.29 was determined for the substance using a relevant test method and in compliance with GLP. The result is considered to be reliable.

Description of key information

Water solubility [whole substance]: <0.52 mg/L (below the limit of detection) at 20°C and pH 6.35 to 7.29 (OECD 105), 2.2E-05 mg/L at 20°C (calculation)

Water solubility [Constituent1]: 2.8E-05 mg/L at 20°C (QSAR)

Water solubility [Constituent 2]: 1.5E-10 mg/L at 20°C (QSAR)

Key value for chemical safety assessment

Water solubility:

0 mg/L

at the temperature of:

20 °C

Additional information

An attempt was made to determine the water solubility of the substance using a column elution method in accordance with OECD Test Guideline 105 and in compliance with GLP. During the main test, six samples were analysed in the first run (0.52 mL/min) and six samples during the second run (0.26 mL/min), each with a sampling interval of one hour. The total elution time was 74 hours. The sample measurement was performed by Gas Chromatography (GC). The test item could not be detected in any of the eluate samples. Therefore, the water solubility of the test substance at 20°C and pH 6.35 to 7.29 was reported to be below the limit of detection i.e. 0.52 mg/L since the deviation between the two measurements is less than 30%. The result is considered to be reliable.

The water solubilities of the main constituents of the submission substance have been predicted using a validated QSAR estimation method. Water solubility values of 2.8E-05 mg/L at 20°C and 1.5E-10 mg/L at 20°C were estimated for Constituent 1 and Constituent 2 respectively. The predicted water solubilities for the constituents is in agreement with the measured water solubility for the whole substance that the submission substance is highly insoluble in water. Based on the percentage amount of each constituent in the submission substance, the predicted water solubility for each constituent was used to determine the weighted average water solubility for the whole substance. Water solubility value of 2.2E-05 mg/L was calculated for the whole substance and this is the water solubility that is used for assessment purposes since this closely reflect the true water solubility of the substance.