Calcium 1,4-bis(2-ethylhexyl) bis(2-sulphosuccinate)

Vapour pressure

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

vapour pressure

Type of information:

experimental study

Adequacy of study:

supporting study

Study period:

2019

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

EU Method A.4 (Vapour Pressure)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Type of method:

static method

Specific details on test material used for the study:

Batch FPAC1822263.
Substance tested is a 56%wt solution of calcium docusate in corn oil. Attempts were made to obtain neat/pure test material but the substance is extremely difficult to handle in the neat form. The form of the substance tested reflects how the substance will be supplied and placed on the market.

Key result

Temp.:

20 °C

Vapour pressure:

9.1 Pa

Remarks on result:

other: mean of runs #1 and #2

Test no.:

#1

Temp.:

20 °C

Vapour pressure:

8.74 Pa

Test no.:

#2

Temp.:

20 °C

Vapour pressure:

9.36 Pa

Key result

Vapour pressure:

70.93 Pa

Conclusions:

Result : 9.1 Pa at 20°C (mean values from runs 1 & 2)

Executive summary:

Run 1: 12.7 g of test material was transferred to a round bottom flask and a magnetic follower added. The test material was placed under vacuum to degas overnight. Upon application of vacuum vigorous outgassing was observed. The total degassing time was approximately 19.5 hours. Pressure at start of analysis was 0.0031 mbar. During the test procedure some gas was observed evolving from the liquid.

Run 2: 12.6 g of test material was transferred to a round bottom flask and a magnetic follower added The test material was placed on secondary vacuum pump to degas overnight. Upon application of vacuum vigorous outgassing was observed. The following day the test material was transferred to main system and degassed overnight. Upon application of the vacuum on the test system, further outgassing was observed. Total degassing time was approximately 43 hours. The vacuum at the start of the analysis was 0.0032 mbar.

As the test substance was a mixture of the registered substance (56%w/w) in corn oil (44%w/w) it is not possible to determine whether the vapour pressure result is for the calcium docusate itself or from (a constituent of) the corn oil in which it is manufactured. Given that docusate calcium is an organic salt it can be reasonably expected that the vapour pressure result obtained in this study is actually resulting from a consistituent (or combination of constituents) of the corn oil. Therefore this experimental study is designated as a supporting study.

Reference 2

Endpoint:

vapour pressure

Type of information:

(Q)SAR

Adequacy of study:

key study

Study period:

May 2018

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

results derived from a valid (Q)SAR model and falling into its applicability domain, with limited documentation / justification

Justification for type of information:

Results derived from a valid (Q)SAR model and falling into its applicability domain, with limited documentation / justification

Qualifier:

no guideline followed

Principles of method if other than guideline:

MPBPWIN estimates vapor pressure (VP) by three separate methods: (1) the Antoine method, (2) the modified Grain method, and (3) the Mackay method.  All three use the normal boiling point to estimate VP.  Unless the user enters a boiling point on the data entry screen,  MPBPWIN uses the estimated boiling point from the adapted Stein and Brown method as described in the Boiling Point section of the MPBPWIN v1.43 model user guide.

Additional information concerning the Antoine method, the modified Grain method and the Mackay method for predicting the vapour pressure of substances can be found within the MPBPWIN v1.43 model help files.

GLP compliance:

no

Type of method:

other: QSAR calculation (MPBPWIN v1.43)

Key result

Temp.:

25 °C

Vapour pressure:

0 Pa

Remarks on result:

other: calculated using the modified Grain method

Conclusions:

The calculated vapour pressure of docusate calcium is 1.7 x 10-26 Pa (Modified Grain method).

Executive summary:

Docusate Calcium is a salt. From salts it is known that they have very low vapour pressures and it is foreseen that experimentally determining data for this endpoint is not technically feasible.

In the absence of reliable experimental data for the pure registered substance, the vapour pressure of docusate calcium was calculated using EPIWIN 4.00 with the module MPBPVP (v1.43). The calculated vapour pressure is 1.7 · 10 ^-26 Pa (Modified Grain method).

Since Docusate Calcium is a salt, a low value was expected and hence the value is considered relevant and reliable.

Description of key information

Docusate calcium is a salt. Such salts are known to have very low vapour pressures. In an initial QSAR calcuation, the vapour pressure of docusate calcium was calculated using the Modified Grain method as 1.7 x 10^-26Pa.

As it was not possible to isolate the substance to produce a representative sample, practical determination of the vapour pressure of docusate calcium itself was not possible. VP testing was therefore conducted on the sample as typically placed on the market. In this testing a result of 9.1 Pa at 20°C (mean values from runs 1 & 2). As the test substance was a mixture of the registered substance (56%w/w) in corn oil (44%w/w) it is not possible to determine whether the vapour pressure result is for the calcium docusate itself or from (a constituent of) the corn oil in which it is manufactured. Given that docusate calcium is an organic salt it can be reasonably expected that the vapour pressure result obtained in this study is actually resulting from a constituent (or combination of constituents) of the corn oil.

The QSAR result is therefore selected as the key study for the CSA.

Key value for chemical safety assessment

Vapour pressure:

0 Pa

at the temperature of:

20 °C