N-isopropylmethacrylamide

Vapour pressure

Link to relevant study record(s)

Reference

Endpoint:

vapour pressure

Type of information:

experimental study

Adequacy of study:

key study

Study period:

Experimental Starting Date: 05 July 2012, Experimental Completion Date: 16 July 2012

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Remarks:

Study conducted to GLP and in compliance with agreed protocols, with no or minor deviations from standard test guidelines and/or minor methodological deficiencies, which do not effect the quality of the relevant results.

Qualifier:

according to guideline

Guideline:

EU Method A.4 (Vapour Pressure)

Deviations:

no

Qualifier:

according to guideline

Guideline:

OECD Guideline 104 (Vapour Pressure Curve)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Type of method:

effusion method: vapour pressure balance

Temp.:

25 °C

Vapour pressure:

3.9 Pa

Results

Recorded temperatures, mass differences and the resulting calculated values of vapor pressure are shown in the following tables and figures:

 

Run 1

Table 3.1 – Vapor Pressure Data

Temperature (ºC)	Temperature (K)	Reciprocal Temperature (K^-1)	Mass Difference (µg)	Mass Difference (kg)	Vapor Pressure (Pa)	Log10Vp
0	273.15	0.003660992	90.34	9.034E-08	0.125415065	-0.901650293
1	274.15	0.003647638	70.43	7.043E-08	0.097774884	-1.009772690
2	275.15	0.003634381	75.99	7.599E-08	0.105493589	-0.976773934
3	276.15	0.003621220	94.21	9.421E-08	0.130787616	-0.883433375
4	277.15	0.003608154	120.00	1.200E-07	0.166590744	-0.778349133
5	278.15	0.003595182	146.12	1.461E-07	0.202851996	-0.692820715
6	279.15	0.003582303	172.48	1.725E-07	0.239446429	-0.620791635
7	280.15	0.003569516	185.34	1.853E-07	0.257299404	-0.589561220
8	281.15	0.003556820	254.32	2.543E-07	0.353061316	-0.452149864
9	282.15	0.003544214	272.66	2.727E-07	0.378521935	-0.421908948
10	283.15	0.003531697	343.04	3.430E-07	0.476227406	-0.322185615

A plot of log₁₀(vapor pressure (Pa)) versus reciprocal temperature (1/T(K)) for Run 1 (see attached background materia) gives the following statistical data using an unweighted least squares treatment.

Slope  -5.31 x 10³
Standard deviation in slope      451

Intercept          18.4
Standard deviation in intercept 1.62

The results obtained indicate the following vapor pressure relationship:

 Log₁₀(Vp (Pa)) = -5.31 x 10³/temp(K) + 18.4

 

The above yields a vapor pressure (Pa) at 298.15 K with a common logarithm of 0.589.

 

This gives a vapor pressure of 3.9 Pa at 298.15 K.

Run 2

Table 3.2 – Vapor Pressure Data

 

Temperature (ºC)	Temperature (K)	Reciprocal Temperature (K^-1)	Mass Difference (µg)	Mass Difference (kg)	Vapor Pressure (Pa)	Log10Vp
0	273.15	0.003660992	117.34	1.173E-07	0.162897982	-0.788084295
1	274.15	0.003647638	120.30	1.203E-07	0.167007221	-0.777264751
2	275.15	0.003634381	130.96	1.310E-07	0.181806032	-0.740391712
3	276.15	0.003621220	155.50	1.555E-07	0.215873839	-0.665799985
4	277.15	0.003608154	165.63	1.656E-07	0.229936874	-0.638391377
5	278.15	0.003595182	224.26	2.243E-07	0.311330335	-0.506778561
6	279.15	0.003582303	163.33	1.633E-07	0.226743885	-0.644464417
7	280.15	0.003569516	256.70	2.567E-07	0.356365366	-0.448104510
8	281.15	0.003556820	273.29	2.733E-07	0.379396537	-0.420906638
9	282.15	0.003544214	310.62	3.106E-07	0.431220140	-0.365300963
10	283.15	0.003531697	322.90	3.229E-07	0.448267927	-0.348462334

 

Data has not been used in calculations, see discussion for explanation.

Run 3

Table 3.3 – Vapor Pressure Data

 

Temperature (ºC)	Temperature (K)	Reciprocal Temperature (K^-1)	Mass Difference (µg)	Mass Difference (kg)	Vapor Pressure (Pa)	Log10Vp
0	273.15	0.003660992	197.92	1.979E-07	0.274763667	-0.561040696
1	274.15	0.003647638	120.00	1.200E-07	0.166590744	-0.778349133
2	275.15	0.003634381	103.77	1.038E-07	0.144059346	-0.841458562
3	276.15	0.003621220	594.64	5.946E-07	0.825512666	-0.083276259
4	277.15	0.003608154	1032.39	1.032E-06	1.433221817	0.156313410
5	278.15	0.003595182	166.65	1.667E-07	0.231352895	-0.635725061
6	279.15	0.003582303	1160.54	1.161E-06	1.611126849	0.207129735
7	280.15	0.003569516	609.46	6.095E-07	0.846086623	-0.072585171
9	282.15	0.003544214	438.84	4.388E-07	0.609222350	-0.215224172
10	283.15	0.003531697	872.09	8.721E-07	1.210684348	0.083030928

 

Data has not been used in calculations, see discussion for explanation.

Run 4

Table 3.4 – Vapor Pressure Data

 

Temperature (ºC)	Temperature (K)	Reciprocal Temperature (K^-1)	Mass Difference (µg)	Mass Difference (kg)	Vapor Pressure (Pa)	Log10Vp
0	273.15	0.003660992	362.00	3.620E-07	0.502548744	-0.298821808
1	274.15	0.003647638	298.58	2.986E-07	0.414505536	-0.382469665
2	275.15	0.003634381	829.65	8.297E-07	1.151766755	0.061364539
5	278.15	0.003595182	10.23	1.023E-08	0.014201861	-1.847654745
6	279.15	0.003582303	78.98	7.898E-08	0.109644475	-0.960013249
7	280.15	0.003569516	4.75	4.750E-09	0.006594217	-2.180836769
9	282.15	0.003544214	34.41	3.441E-08	0.047769896	-1.320845706

 

Data has not been used in calculations, see discussion for explanation.

Discussion

After the preliminary run, a number of main sequences were started which resulted in erratic vapor pressure values within each run. There were no obvious reasons apparent for this erratic behavior. The same sample of the test item was then run on another instrument and this also resulted in erratic vapor pressure values. Finally, a fresh sample of the test item was used for the main sequence which resulted in the first run showing good correlation for the straight line graph (see Figure 3.2 - attached background material), with the subsequent runs becoming increasingly erratic (see Figures 3.3, 3.4, and 3.5 - attached background material). This suggested that interaction between the test item and the vapor pressure balance may be responsible, for the increasingly erratic vapor pressure values with time. Therefore, as the run 1 shows good correlation and has been in contact with the vapor pressure balance for the least period of time, it has been used for calculating the definitive vapor pressure for the test item.

Conclusions:

The vapor pressure of the test item has been determined to be 3.9 Pa at 25 ºC.

Executive summary:

Method

The vapor pressure was determined using a vapor pressure balance with measurements being made at several temperatures and linear regression analysis used to calculate the vapor pressure at 25 °C.

The determination was carried out using a procedure designed to be compatible with Method A4 Vapour Pressure of Commission Regulation (EC) No 440/2008 of 30 May 2008 and Method 104 of the OECD Guidelines for Testing of Chemicals, 23 March 2006.

Conclusion

The vapor pressure of the test item has been determined to be 3.9 Pa at 25 ºC.

Description of key information

The vapor pressure of the test item has been determined to be 3.9 Pa at 25 ºC.

Key value for chemical safety assessment

Vapour pressure:

3.9 Pa

at the temperature of:

25 °C

Additional information

The vapor pressure was determined using a vapor pressure balance with measurements being made at several temperatures and linear regression analysis used to calculate the vapor pressure at 25 °C.

The determination was carried out using a procedure designed to be compatible with Method A4 Vapour Pressure of Commission Regulation (EC) No 440/2008 of 30 May 2008 and Method 104 of the OECD Guidelines for Testing of Chemicals, 23 March 2006.

The vapor pressure of the test item has been determined to be 3.9 Pa at 25 ºC.