Monophosphothiamine

Vapour pressure

Link to relevant study record(s)

Reference

Endpoint:

vapour pressure

Type of information:

experimental study

Adequacy of study:

key study

Study period:

12 Jan - 17 Jan 2017

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 104 (Vapour Pressure Curve)

Qualifier:

according to guideline

Guideline:

EU Method A.4 (Vapour Pressure)

GLP compliance:

no

Type of method:

effusion method: Knudsen cell

Specific details on test material used for the study:

Storage conditions: Ambient temperature (10 to 30 °C), dry

Temp.:

20 °C

Vapour pressure:

< 0 hPa

Temp.:

25 °C

Vapour pressure:

< 0 hPa

Temp.:

50 °C

Vapour pressure:

< 0 hPa

Results
Vapour pressure was measured in the temperature range of 30 to 80 °C. The first measurement showed a typical deviation caused by volatile impurities or volatile parts of the test item (e.g. loss of hydrate from the molecule) at the beginning of the measurement. Therefore, the measurement was repeated and only this second measurement was used for the evaluation.

Table 1 – Meaured vapour pressure and corresponding temperatures

Temperature [°C]	Vapour pressure [hPa]
30	6.97E-04
40	1.33E-03
50	6.32E-04
60	3.58E-05
70	2.02E-06
80	5.87E-06
30*	1.25E-05
40*	6.14E-06
50*	2.85E-06
60*	2.99 E-06
70*	3.92 E-06
80*	6.35 E-06

*second measurement     

                                   

The test did not yield vapour pressures sufficiently high to extrapolate to 20, 25 and 50 °C. Therefore, these were calculated according to the Antoine equation. Constant B was assumed to be equal to -5000 and constant C equal to 273.15. The detection limit (1.0E-05 hPa) at the highest measurement point (80 °C) was used for the calculation, as all measured vapour pressures from the second measurement were around or below the detection limit. The constant A was calculated to be equal to 9.16

Subsequently, values for 20, 25 and 50 °C were calculated using the Antoine constants A, B and C as shown in Table 2.

Table 2 – Antoine parameters and extrapolated vapour pressures

T [°C]	p [hPa]	p [Pa]	log p = A + B/(C+T)
20	< 1.3E-08	< 1.3E-06	A = 9.16
25	< 2.4E-08	< 2.4E-06	B = -5000
50	< 4.9E-07	< 4.9E-05	C = 273.15

 

Description of key information

< 1.3E-08 hPa at 20 °C

< 2.4E-08 hPa at 25 °C

< 4.9E-07 hPa at 50 °C

(OECD 104, estimated using Antoine equation)

Additional information

Vapour pressures obtained were not sufficiently high to extrapolate to 20, 25 and 50 °C. Therefore, these values were estimated using the Antoine equation.