Lime (Citrus aurantifolia), ext.

Vapour pressure

Link to relevant study record(s)

Reference

Endpoint:

vapour pressure

Type of information:

(Q)SAR

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: The vapour pressure of the natural complex substances was calculated from the vapour pressures of the known constituents estimated by the QSAR Mpbpwin v.143.

Justification for type of information:

QSAR prediction

Reason / purpose for cross-reference:

reference to same study

Qualifier:

no guideline followed

Principles of method if other than guideline:

This parameter varies as the composition of the mixture changes during evaporation. For Type 1 NCSs with known constituents the “initial” vapour pressure can be calculated as the sum of the partial pressure of the known constituents. Also a range of the vapour pressure can be given. Therefore, the first approach will be a calculation of the vapour pressure based on constituents. Figure (attached as picture) shows that the measured values are very similar to the estimated values for various citrus oil constituents. Only for constituents with low measured vapour pressure, the estimation method overestimates the vapour pressure. However, it is considered that these extreme non-volatile constituents (<1 Pa) are not relevant for the volatility of the NCS. It is recommended in the NCS protocol to calculate the initial vapour pressure based on the vapour pressures of the individual constituents. From the comparison between estimated and measured data in the figure, it can be concluded that the epiwin calculation method can be considered as reliable. Therefore, the epiwin estimation method is considered as relevant to estimate vapour pressures for this group of constituents. For the initial vapour pressure, the estimated values are used in the calculation. The “initial” vapour pressure is calculated as the sum of the partial pressure of the constituents (based on molecular fraction).

GLP compliance:

no

Type of method:

other: Calculation by estimation

Key result

Temp.:

25 °C

Vapour pressure:

170.9 Pa

Remarks on result:

other: Initial vapour pressure

Substance	CAS	Fraction	Estimated vapour pressure (Pa at 25 degrees Celsius)	Molecular weight
D-limonene	5989-27-5	0.440	193	136.24
γ-terpinene	99-85-4	0.100	153	136.24
Citral	5392-40-5	0.030	12.2	152.24
Terpinolene	586-62-9	0.060	133	136.24
Beta-Pinene	127-91-3	0.100	334	136.24
Neryl Acetate	141-12-8	0.010	6.17	196.29
Myrcine B	123-35-3	0.010	320	136.24
Alpha-Terpineol	98-55-5	0.070	2.62	154.25
5-Geranoxy-7-methoxycoumarin	7380-39-4	0.020	0.0000026	328.41
Alpha-Bergamotene	13474-59-4	0.010	3.69	204.36
Alpha-Terpinene	99-86-5	0.010	222	136.24
Beta-Bisabolene	495-61-4	0.010	2.93	204.36
Farnesene	4602-84-0	0.010	0.00525	222.37
Para-Cymene	99-87-6	0.010	152	134.22
1,4-cineole	470-67-7	0.040	238	154.25
alpha-pinene	7785-70-8	0.020	536	136.24
Sabinene	3387-41-5	0.010	981	136.24
Furocoumarins	N/A	0.030	N/A	N/A

Weight percentages of constituents are converted to molar percentages using the molecular weight (MW).

The sum of the vapour pressures multiplied by the fractions in the mixture is 169.15 Pa. To correct for the 4% unknown constituents (assuming the average vapour pressure for the unknown constituents is similar to tha average vapour pressure of the known constituents), this number is multiplied by 1 / 0.99.

Conclusions:

The initial vapour pressure of lime oil is 170.9 Pa at 25 degrees Celsius.

Executive summary:

The initial vapour pressure of lime oil was estimated by calculation. Vapour pressures for the known constituents were estimated using the QSAR MPBPWIN v 1.43. The sum of the vapour pressures multiplied by the molecular fraction of the substance in the NCS was taken as an initial estimate for the vapour pressure of the mixture. The number obtained was then corrected for the unknown constituents (assuming the average vapour pressure for the unknown constituents is similar to the average vapour pressure of the known constituents).

The initial vapour pressure of lime oil was found to be 170.9 Pa at 25 degrees Celsius. The vapour pressure of the constituents ranges from 2.6 x 10^-6 to 981 Pa.

Description of key information

Initial Vapour pressure: 170.9 Pa at 25 degrees Celsius

Key value for chemical safety assessment

Vapour pressure:

170.9 Pa

at the temperature of:

25 °C

Additional information

In a key study, the vapour pressure of lime oil was calculated using estimates of the vapour pressures of its' constituents, in line with the NCS protocol. The initial vapour pressure of lime oil was found to be 170.9 Pa at 25 degrees Celsius. The vapour pressure for the constituents ranges from 2.6.10^-6 to 981 Pa.