L-Aspartic acid, N,N'-1,2-ethanediylbis-, sodium salt (1:3)

Vapour pressure

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

vapour pressure

Type of information:

experimental study

Adequacy of study:

key study

Study period:

1993-06-21 to 1993-06-23

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 104 (Vapour Pressure Curve)

Deviations:

no

GLP compliance:

yes

Type of method:

static method

Key result

Temp.:

25 °C

Vapour pressure:

1.9 Pa

A total of 97 measurements were made. Mean of selected measurements at 36.25^oC (#30 to 44), 30.08^oC (#55 to 66) and 24.55^oC (#80 to 97) fitted by method of Clark & Grew to give value at 25^oC.

Conclusions:

In a GLP study conducted according to OECD Guideline 104, the vapour pressure of trisodium EDDS at 25°C was calculated to be 1.9 Pa

Executive summary:

In a GLP study conducted according to OECD Guideline 104, the vapour pressure of trisodium EDDS was measured using the static method at three temperatures (36.25, 30.08 and 24.55^oC) and the value at 25^oC (calculated by fitting the data using the method of Clark and Grew) was 1.9 Pa.

Reference 2

Endpoint:

vapour pressure

Type of information:

experimental study

Adequacy of study:

supporting study

Study period:

1996-10-29 to 1996-10-31

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 104 (Vapour Pressure Curve)

Deviations:

not specified

GLP compliance:

yes

Type of method:

static method

Key result

Temp.:

20 °C

Vapour pressure:

0.38 Pa

Mean of selected measurements at 37^oC (#30 to 69), 29.96^oC (#77 to 87) and 24.31^oC (#100 to 117) was 5.16, 1.88 and 0.75 Pa, respectively

Conclusions:

In a GLP study conducted according to OECD Guideline 104, the vapour pressure of trisodium EDDS at 20°C was determined to be 0.38 Pa

Executive summary:

In a GLP study conducted according to OECD Guideline 104, the vapour pressure of trisodium EDDS was measured using the static method at three temperatures (37, 29.96 and 24.31^oC) and the value at 20^oC (calculated by fitting the data using the method of Clark and Grew) was 0.38 Pa.

Reference 3

Endpoint:

vapour pressure

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

supporting study

Study period:

13 to 29 May 2002

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Qualifier:

according to guideline

Guideline:

EU Method A.4 (Vapour Pressure)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Type of method:

effusion method: vapour pressure balance

Key result

Temp.:

25 °C

Vapour pressure:

< 0 Pa

A total of 5 runs were carried out, each consisting of 11 data entires. The temperature range is between 120°C to 130°C. No statistical analysis is given for any run, due to the nature of the plot. It was considered more appropriate to impose a regression slope on a chosen data point (129°C of run 5) as an estimate of the maximum value for the vapour pressure at 25°C.

Conclusions:

In a GLP study conducted according to EU Method A.4, the vapour pressure of EDDS acid at 25°C was calculated to be less than 1.7 x 10-4 Pa.

Executive summary:

In a GLP study conducted according to EU Method A.4, the vapour pressure of EDDS acid was assessed using the vapour pressure balance system, with measurements made at several temperatures and from imposing a regression slope. The value at 25^oC was calculated as less than 1.7 x 10 -4 Pa.

[Data on EDDS free acid is considered relevant to use for understanding the potential vapour pressure of trisodium EDDS, and is acceptable for using as read-across.]

Description of key information

In two GLP studies conducted according to OECD Guideline 104 (using the static method), the vapour pressure of trisodium EDDS was determined .to be 0.38 Pa at 20°C (Krips and van Genderen, 1996) and 1.9 Pa at 25°C (de Vries and van Genderen, 1993).

However, a very low vapour pressure (of 6.53 x 10-15 Pa) was calculated (based on chemical structure) for trisodium EDDS using Syracuse software. 7

In addition, in a GLP study conducted according to EU Method A.4, the vapour pressure of EDDS acid was assessed using the vapour pressure balance system, with measurements made at several temperatures and from imposing a regression slope. The value at 25°C was calculated as less than 1.7 x 10 -4 Pa (Tremain, 2002).

[Data on EDDS acid is considered relevant to use for understanding the potential vapour pressure of trisodium EDDS, and is acceptable for using as read-across information.]

Key value for chemical safety assessment

Vapour pressure:

0.002 kPa

at the temperature of:

25 °C

Additional information

In two GLP studies (conducted according to OECD Guideline 104) using the static method, the vapour pressure of trisodium EDDS was determined to be 0.38 Pa at 20°C (Krips and van Genderen, 1996) and 1.9 Pa at 25°C (de Vries and van Genderen, 1993). However, in comparison with other related sodium salts, these values appear to be abnormally high. [In view of the nature of the substance, the vapour pressure is probably due to volatile impurities with the substance having a much lower value.]

Therefore, the vapour pressure of trisodium EDDS was calculated using the Syracuse Software, Module MPBP v.1.10. This software packages estimates vapour pressure based on chemical structure. The estimated value for trisodium EDDS was 4.97 x 10^-17 mm Hg, or 6.53 x 10^-15 Pa. Very low vapour pressures are expected for other simple salts of the EDDS moiety.

 

The reason for the marked difference between the experimental results and that of the computer model is likely to be associated with the hygroscopic nature of trisodium EDDS, the high measured values being attributed to water vapour generated from adsorbed water not completely removed during the sample preparation steps.

In addition, in a GLP study conducted according to EU Method A.4, the vapour pressure of EDDS acid was assessed using the vapour pressure balance system, with measurements made at several temperatures and from imposing a regression slope. The value at 25^oC was calculated as less than 1.7 x 10 -4 Pa. [Data on EDDS free acid is considered relevant to use for understanding the potential vapour pressure of trisodium EDDS, and is acceptable for using as read-across information.]