Quaternary ammonium compounds, trimethylsoya alkyl, chlorides

Vapour pressure

Link to relevant study record(s)

Reference

Endpoint:

vapour pressure

Type of information:

experimental study

Adequacy of study:

key study

Study period:

January 2018

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

Principles of method if other than guideline:

The test substance is exposed to a known and constant nitrogen flow in the oven of a Thermo Gravimetric Analyzer (TGA) at defined elevated isothermal temperatures. The evaporation rate (vT) at each test temperature is determined by monitoring the weight loss over appropriate periods of time. The relationship between the logarithm of the evaporation rate (log vT) and the reciprocal of the temperature (1/T) is linear. By linear extrapolation of this relationship to 20°C the evaporation rate at this temperature (vT,20) is normally calculated by linear regression (least squares method). This evaporation rate is used to calculate the vapor pressure at 20°C (pT,20) by using the linear relationship between log vT,20 and log pT,20. This relationship is determined by calibration of the test equipment with five reference substances with known vapor pressures at 20°C. This method is suitable for substances with (very) low vapor pressures and with purity as close as possible to 100% to avoid the misinterpretation of measured weight losses from more volatile impurities. The vapor pressure of a substance is expressed in Pascal (Pa).

GLP compliance:

no

Other quality assurance:

other: ISO 9001

Type of method:

effusion method: isothermal thermogravimetry

Key result

Test no.:

#1

Temp.:

ca. 20 °C

Vapour pressure:

ca. 0 Pa

Calibration

The calibration was carried out less than a month before this study. For each reference substance the evaporation rate at 20°C, determined in this calibration, and the known vapor pressure are mentioned in the table below. The calibration resulted in the following values:

- constant C : 1.208

- constant D : 3.996

- r2 : 0.9976

- n : 5

Reference substance	P20 [Pa]	log p20	v20 [g.cm-2.h-1]	log v20
Naphthalene	7.20 x 10	+ 0.857	2.45 x 10-3	- 2.610
n-Octadecane	1.46 x 10-2	- 1.835	1.04 x 10-5	- 4.985
Hexachlorobenzene	1.47 x 10-3	- 2.833	2.28 x 10-6	- 5.642
Chrysene	8.40 x 10-7	- 6.076	9.06 x 10-9	- 8.043
Benzo(g,h,i)perylene	1.33 x 10-8	- 7.876	9.93 x 10-11	-10.003

Check of nitrogen flow rate

The flow rate was within the range of 52 mL/min.

Vapor pressure of test substance

The evaporation rate of the test substance was measured at 152°C till 209°C:

Temperature [°C]	v20 [g.cm-2.h-1]	log v20
151.9	2.52 x 10-4	-3.600
161.3	4.43 x 10-4	-3.354
170.8	8.78 x 10-4	-3.057
180.4	1.73 x 10-3	-2.761
190.0	3.41 x 10-3	-2.467
199.7	7.23 x 10-3	-2.141
209.4	1.46 x 10-2	-1.836

Log V(T) = -6331.4* (1/T) + 11.2366

At 20°C,

Log V(20) = -6331.4/293.15 + 11.2366 = -10.361

V20 = 10-10.361 = 4.355 x 10-11 g.cm-2.h-1.

The evaporation rate at 20°C can be calculated from the measured rates between 152°C and 209°C by linear extrapolation of log vT versus 1/T according to equation (2).

This results in: v20 = 4.355 x 10-11 g.cm-2.h-1.

Log p(20) = 1.2077 * log V20 + 3.9963 = 1.2077 * (-10.361)+ 3.9963 = -8.517

Vapour pressure of test substance at 20°C = p(20) = 10-8.517 = 3.0*10-9 Pa

The vapor pressure of the test substance at 20°C can be calculated by using equation (3).

This results in: p20 = 3.0 x 10-9 Pa.

Results

The vapor pressure of test substance at 20°C can be calculated by using equation (3).

Vapour pressure of test substance at 20°C = p(20) = 10-8.517 = 3.0E-9 Pa

Conclusions:

Under the study conditions, the vapour pressure of the test substance at 20°C was determined to be 3.0E-9 Pa.

Executive summary:

A study was conducted to determine the vapour pressure of the test substance, TMAC S (88.3% active), using the isothermal thermogravimetry effusion method, according to EU Method A.4, in compliance with ISO-9001. Under the study conditions, the vapour pressure of the test substance was determined to be 3.0E-9 Pa at 20°C (Boerdijk, 2018).

Description of key information

The vapour pressure of the test substance was determined using the isothermal thermogravimetric effusion method, according to EU Method A.4 (Boerdijk, 2018).

Key value for chemical safety assessment

Vapour pressure:

0 Pa

at the temperature of:

20 °C