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Vapour pressure

Link to relevant study record(s)

Reference

Endpoint:

vapour pressure

Type of information:

experimental study

Adequacy of study:

key study

Study period:

7 November - 14 November 2022

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Justification for type of information:

Non-GLP study; suitable for registration and classification.

Qualifier:

according to guideline

Guideline:

OECD Guideline 104 (Vapour Pressure Curve)

Deviations:

not specified

GLP compliance:

no

Type of method:

effusion method: Knudsen cell

Specific details on test material used for the study:

No further details in the study report

Key result

Test no.:

#1

Temp.:

296.85 K

Vapour pressure:

>= 0.081 - <= 0.084 Pa

Key result

Test no.:

#2

Temp.:

300.15 K

Vapour pressure:

>= 0.07 - <= 0.073 Pa

Key result

Test no.:

#3

Temp.:

307.05 K

Vapour pressure:

>= 0.082 - <= 0.086 Pa

Key result

Test no.:

#4

Temp.:

314.15 K

Vapour pressure:

>= 0.011 - <= 0.012 Pa

Key result

Test no.:

#5

Temp.:

321.65 K

Vapour pressure:

>= 0.045 - <= 0.047 Pa

Table 2. Experimental Results

Mass loss (mg)	Mass loss duration (s)	Vapour pressure (Pa)*	Log10 (p)*	Temperature (K)	1/T (1/K)
0.015	600	0.0808 ; 0.0843	-1.0924 ; -1.0741	296.85	3.369 x 10^-3
0.013	600	0.0705 ; 0.0735	-1.1520 ; -1.1337	300.15	3.332 x 10^-3
0.015	600	0.0822 ; 0.0858	-1.0850 ; -1.0667	307.05	3.257 x 10^-3
0.002	600	0.0111 ; 0.0116	-1.9549 ; -1.9366	314.15	3.183 x 10^-3
0.008	600	0.0449 ; 0.0468	-1.3481 ; -1.3298	321.65	3.109 x 10^-3

*: lowest and highest values calculated depending on molar mass value used.

Conclusions:

In conclusion, the vapour pressure of RED HF2 is below 0.29 Pa at 48.4°C and therefore the vapour pressure of RED HF2 at 20°C and 25°C is below 0.29 Pa.

Executive summary:

The vapour pressure of RED HF2 was measured using the Knudsen effusion method as described in EU method A.4 and OECD 104.

 

In this method, the mass of the test substance flowing out per unit of time of a Knudsen cell in the form of vapour, through a micro-orifice under ultra-vacuum conditions was determined at various specified temperatures (from 23.8°C to 48.4°C). However, the mass loss observed was of the same order of magnitude as the baseline mass variation. As the test item started to spread from the lid hole, no new test with higher temperatures was performed.

The Hertz-Knudsen equation was still used to calculate the vapour pressure corresponding to the observed mass loss rate.

The Log₁₀ (Vapour Pressure (Pa)) was plotted against 1/T (K) but no linear function was obtained and therefore no vapour pressure can be calculated by extrapolating these results.

 

Considering the accuracy of the TG-DSC integrated balance (50 µg), no significant mass-loss was observed along the measurements even with the highest temperature (48.4°C).

Therefore an upper value of vapour pressure can be given considering the precision of the balance:

Using the Hertz-Knudsen formula with the highest temperature (48.4°C) and a mass-loss corresponding to the precision of the balance (0.05 mg) gives a vapour pressure of 0.29 Pa. The pressures calculated from the thermograms are thus of the same order of magnitude as the pressure obtained using the precision of the balance.

 

In conclusion, the vapour pressure of RED HF2 is below 0.29 Pa at 48.4°C and therefore the vapour pressure of RED HF2 at 20°C and 25°C is below 0.29 Pa.

 

Description of key information

In conclusion, the vapour pressure of RED HF2 is below 0.29 Pa at 48.4°C and therefore the vapour pressure of RED HF2 at 20°C and 25°C is below 0.29 Pa.

Key value for chemical safety assessment

Vapour pressure:

0.29 Pa

at the temperature of:

48.4 °C

Additional information

In this method, the mass of the test substance flowing out per unit of time of a Knudsen cell in the form of vapour, through a micro-orifice under ultra-vacuum conditions was determined at various specified temperatures (from 23.8°C to 48.4°C). However, the mass loss observed was of the same order of magnitude as the baseline mass variation. As the test item started to spread from the lid hole, no new test with higher temperatures was performed.

The Hertz-Knudsen equation was still used to calculate the vapour pressure corresponding to the observed mass loss rate.

The Log₁₀ (Vapour Pressure (Pa)) was plotted against 1/T (K) but no linear function was obtained and therefore no vapour pressure can be calculated by extrapolating these results.

 

Considering the accuracy of the TG-DSC integrated balance (50 µg), no significant mass-loss was observed along the measurements even with the highest temperature (48.4°C).

Therefore an upper value of vapour pressure can be given considering the precision of the balance:

Using the Hertz-Knudsen formula with the highest temperature (48.4°C) and a mass-loss corresponding to the precision of the balance (0.05 mg) gives a vapour pressure of 0.29 Pa. The pressures calculated from the thermograms are thus of the same order of magnitude as the pressure obtained using the precision of the balance.