N-(2-hydroxyethyl)dodecanamide

Vapour pressure

Link to relevant study record(s)

Reference

Endpoint:

vapour pressure

Type of information:

experimental study

Adequacy of study:

key study

Study period:

19 July 2017 - 22 May 2018

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Remarks:

Study was conducted in accordance with international guidelines and in accordance with GLP. Not all experimental validity criteria were met. The test item was determined to have a vapour pressure that was too low to achieve reliable and repeatable measurement. As a consequence statistical analysis was not possible. A worst case limit value, based on a measured data point and historical lab data, was determined and reported.

Qualifier:

according to guideline

Guideline:

EU Method A.4 (Vapour Pressure)

Version / remarks:

Regulation (EC) 440/2008 of 30 May 2008

Deviations:

yes

Remarks:

Due to methodological limitations and the properties of the test item, only one vapour pressure value (at 25 °C) was determined.

Qualifier:

according to guideline

Guideline:

OECD Guideline 104 (Vapour Pressure Curve)

Version / remarks:

23 March 2006

Deviations:

yes

Remarks:

Due to methodological limitations and the properties of the test item, only one vapour pressure value (at 25 °C) was determined.

GLP compliance:

yes (incl. QA statement)

Type of method:

effusion method: vapour pressure balance

Key result

Temp.:

25 °C

Vapour pressure:

< 0.009 Pa

Remarks on result:

other: Limit Value

Evaluation of Data:

The vapour pressure is related to the observed mass difference using Equation 1:

 

Equation 1:

V_p= (δm.g)/A

 

Where:

V_p = vapour pressure (Pa)

δm = mass difference (kg)

g = acceleration due to gravity (9.813 m s^-2)

A = area of the orifice (7.06858 x 10^-6m²)

 

 

Vapour pressure is related to temperature using Equation 2:

Log₁₀V_p= slope/T + intercept

 

Where

V_p = vapour pressure (Pa)

T = temperature (K)

 

A plot of Log10 V_p(Pa) versus reciprocal temperature (1/T(K)) therefore gives a straight-line graph.

 

The vapour pressure of the sample was measured over a range of temperatures to enable extrapolation to 298.15 K.

 

 

Results:

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

 

Table 1:          Vapour Pressure Data, Run 7

Temperature	Temperature	Reciprocal Temperature	Mass Difference	Mass Difference	Vapour Pressure	Log10Vp
°C	K	K^-1	µg	kg	Pa
45	318.15	0.0031432	13.58	1.358 x 10^-8	0.0188525	-1.724631
46	319.15	0.0031333	7.49	7.490 x 10^-9	0.0103980	-1.983049
47	320.15	0.0031235	6.39	6.390 x 10^-9	0.0088710	-2.052030
48	321.15	0.0031138	6.09	6.090 x 10^-9	0.0084545	-2.072913
49	322.15	0.0031041	3.89	3.890 x 10^-9	0.0054003	-2.267581
50	323.15	0.0030945	5.49	5.490 x 10^-9	0.0076215	-2.117958
51	324.15	0.0030850	10.08	1.008 x 10^-8	0.0139936	-1.854070
52	325.15	0.0030755	5.49	5.490 x 10^-9	0.0076215	-2.117958
53	326.15	0.0030661	5.29	5.290 x 10^-9	0.0073439	-2.134075
54	327.15	0.0030567	4.79	4.790 x 10^-9	0.0066497	-2.177195
55	328.15	0.0030474	4.89	4.890 x 10^-9	0.0067886	-2.168222

No statistical analysis is given due to the nature of the plot.

 

 

Table 2:          Vapour Pressure Data, Run 8

Temperature	Temperature	Reciprocal Temperature	Mass Difference	Mass Difference	Vapour Pressure	Log10Vp
°C	K	K^-1	µg	kg	Pa
45	318.15	0.0031432	8.39	8.390 x 10^-9	0.0116475	-1.933768
46	319.15	0.0031333	4.69	4.690 x 10^-9	0.0065109	-2.186358
47	320.15	0.0031235	4.79	4.790 x 10^-9	0.0066497	-2.177195
48	321.15	0.0031138	3.79	3.790 x 10^-9	0.0052615	-2.278891
49	322.15	0.0031041	4.39	4.390 x 10^-9	0.0060944	-2.215066
50	323.15	0.0030945	3.99	3.990 x 10^-9	0.0055391	-2.256558
51	324.15	0.003085	6.59	6.590 x 10^-9	0.0091486	-2.038645
52	325.15	0.0030755	7.89	7.890 x 10^-9	0.0109533	-1.960453
53	326.15	0.0030661	7.29	7.290 x 10^-9	0.0101204	-1.994803
54	327.15	0.0030567	6.19	6.190 x 10^-9	0.0085933	-2.065840
55	328.15	0.0030474	9.39	9.390 x 10^-9	0.0130357	-1.884865

No statistical analysis is given due to the nature of the plot.

 

 

Table 3:          Vapour Pressure Data, Run 9

Temperature	Temperature	Reciprocal Temperature	Mass Difference	Mass Difference	Vapour Pressure	Log10Vp
°C	K	K^-1	µg	Kg	Pa
45	318.15	0.0031432	11.58	1.158 x 10^-9	0.0160760	-1.793822
46	319.15	0.0031333	6.49	6.490 x 10^-9	0.0090098	-2.045286
47	320.15	0.0031235	4.99	4.990 x 10^-9	0.0069274	-2.159430
48	321.15	0.0031138	6.89	6.890 x 10^-9	0.0095651	-2.019311
49	322.15	0.0031041	8.09	8.090 x 10^-9	0.0112310	-1.949582
50	323.15	0.0030945	5.99	5.990 x 10^-9	0.0083157	-2.080104
51	324.15	0.003085	6.59	6.590 x 10^-9	0.0091486	-2.038645
52	325.15	0.0030755	5.69	5.690 x 10^-9	0.0078992	-2.102418
53	326.15	0.0030661	9.58	9.580 x 10^-9	0.0132995	-1.876165
54	327.15	0.0030567	7.99	7.990 x 10^-9	0.0110922	-1.954984
55	328.15	0.0030474	7.49	7.490 x 10^-9	0.0103980	-1.983049

No statistical analysis is given due to the nature of the plot.

 

 

Table 4:          Vapour Pressure Data, Run 10

Temperature	Temperature	Reciprocal Temperature	Mass Difference	Mass Difference	Vapour Pressure	Log10Vp
°C	K	K^-1	µg	kg	Pa
45	318.15	0.0031432	10.28	1.028 x 10^-8	0.0142713	-1.845537
46	319.15	0.0031333	9.68	9.680 x 10^-9	0.0134383	-1.871655
47	320.15	0.0031235	9.78	9.780 x 10^-9	0.0135771	-1.867192
48	321.15	0.0031138	6.19	6.190 x 10^-9	0.0085933	-2.065840
49	322.15	0.0031041	5.59	5.590 x 10^-9	0.0077604	-2.110119
50	323.15	0.0030945	5.49	5.490 x 10^-9	0.0076215	-2.117958
51	324.15	0.003085	4.59	4.590 x 10^-9	0.0063721	-2.195718
52	325.15	0.0030755	7.59	7.590 x 10^-9	0.0105369	-1.977289
53	326.15	0.0030661	5.19	5.190 x 10^-9	0.0072050	-2.142363
54	327.15	0.0030567	10.48	1.048 x 10^-8	0.0145489	-1.837169
55	328.15	0.0030474	8.59	8.590 x 10^-9	0.0119251	-1.923537

No statistical analysis is given due to the nature of the plot.

 

 

Discussion:

The appearance of the test item did not change under the conditions used in the determination.

 

No statistical analyses were performed because the balance readings were too low and variable for a line of best fit to have any meaning. Instead it was considered more appropriate to impose a regression slope on a chosen data point to provide an estimate of the maximum value for the vapour pressure at 25°C. Runs 7 to 10 have been included to demonstrate the behaviour of the test item under the test conditions; Runs 1 to 6 were similar and no statistical analysis could be obtained due to the nature of these plots.

 

Run 10 was chosen because the sample had been under vacuum for the longest period prior to this run and so degassing would have been the most complete. The reading at 45°C (318 K) was chosen because this is the data point which gives the highest estimated vapour pressure at any given temperature when a slope of –1000 K is imposed upon it.

 

The value of –1000 K is an in-house value and is the shallowest slope observed whilst determining the vapour pressure on a wide range of samples using the vapour pressure balance method. Extrapolation to 25°C gave a vapour pressure of 8.78 x 10^-3Pa which has been taken as a maximum for this substance.

 

The results may represent rounded values obtained by calculations based on the exact raw data.

 

 

Conclusion:

The vapour pressure of the test item has been determined to be less than 8.8 x 10-3 Pa at 25°C.

Conclusions:

The vapour pressure of the test item has been determined to be less than 8.8 x 10-3 Pa at 25 °C.

Executive summary:

EU Method A.4. – The vapour pressure of the test item was sought using the vapour pressure balance method. The procedure employed was designed to be compatible with Method A.4. Vapour Pressure of Commission Regulation (EC) No 440/2008 of 30 May 2008.

 

The test item was subject to a sequence of runs to determine vapour pressure. A sample of test item was held under vacuum for approximately 24.5 hours. Temperature and mass differential readings were measured across a temperature range of 45 and 55 °C following the outcome of a preliminary test. Values measured across this temperature range showed a poor linear response.

 

In light of the poor linear response of the test item to experimental conditions, no statistical analyses were performed because the readings were too variable for a line of best fit to have any meaning. It was considered more appropriate to impose a regression slope on a chosen data point to provide an estimate of the maximum value for the vapour pressure at 25 °C. This methodology was applied to a reading at 45 °C (318 K) obtained during the final test run. This value was chosen as the test item had been under vacuum for the longest period prior to this run and so degassing would have been the most complete. Further this temperature resulted in the highest estimated vapour pressure at any given temperature when a slope of –1000 K is imposed upon it. The value of –1000 K is an in-house laboratory value. It is the shallowest slope observed whilst determining the vapour pressure on a wide range of samples using the vapour pressure balance method. Extrapolation to 25 °C gave a vapour pressure of 8.78 x 10^-3Pa which has been taken as a maximum for this substance.

 

A vapour pressure limit value of the test item has been determined to be 8.8 x 10^-3 Pa at 25 °C.

Description of key information

Vapour Pressure: < 8.8 x 10 ^-3 Pa at 25 ºC.; EU Method A.4.; R. Butler (2018)

Key value for chemical safety assessment

Vapour pressure:

0.009 Pa

at the temperature of:

25 °C

Additional information

EU Method A.4. – The vapour pressure of the test item was determined using the vapour pressure balance method. The procedure employed was designed to be compatible with Method A.4. Vapour Pressure of Commission Regulation (EC) No 440/2008 of 30 May 2008.

 

The test item was subject to a sequence of runs to determine vapour pressure. A sample of test item was held under vacuum for approximately 24.5 hours. Temperature and mass differential readings were measured across a temperature range of 45 and 55 °C following the outcome of a preliminary test. Values measured across this temperature range showed a poor linear response.

 

In light of the poor linear response of the test item to experimental conditions, no statistical analyses were performed because the readings were too variable for a line of best fit to have any meaning. It was considered more appropriate to impose a regression slope on a chosen data point to provide an estimate of the maximum value for the vapour pressure at 25 °C. This methodology was applied to a reading at 45 °C (318 K) obtained during the final test run. This value was chosen as the test item had been under vacuum for the longest period prior to this run and so degassing would have been the most complete. Further this temperature resulted in the highest estimated vapour pressure at any given temperature when a slope of –1000 K is imposed upon it. The value of –1000 K is an in-house laboratory value. It is the shallowest slope observed whilst determining the vapour pressure on a wide range of samples using the vapour pressure balance method. Extrapolation to 25 °C gave a vapour pressure of 8.78 x 10^-3Pa which has been taken as a maximum for this substance.

 

A vapour pressure limit value of the test item has been determined to be 8.8 x 10^-3Pa at 25 °C.