mecoprop-P (ISO); (R)-2-(4-chloro-2-methylphenoxy)propionic acid

Vapour pressure

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

vapour pressure

Type of information:

experimental study

Adequacy of study:

key study

Study period:

02 February 1999 to 22 June 1999

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 104 (Vapour Pressure Curve)

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method A.4 (Vapour Pressure)

Deviations:

no

Qualifier:

according to guideline

Guideline:

EPA OPPTS 830.7950 (Vapor Pressure)

Deviations:

no

GLP compliance:

yes

Type of method:

effusion method: vapour pressure balance

Key result

Test no.:

#1

Temp.:

25 °C

Vapour pressure:

0.001 Pa

Vapour Pressure Results: Run 1

Temperature (°C)	Mass Difference (μg)	Vapour Pressure (Pa)	1/Temperature (1/K)	Log Vapour Pressure
26.0	1.01	0.00166	0.00334	-2.78
27.0	1.14	0.00188	0.00333	-2.73
29.0	1.45	0.00239	0.00331	-2.62
31.0	1.63	0.00268	0.00329	-2.57
32.0	2.13	0.00351	0.00328	-2.45
34.5	2.67	0.00440	0.00325	-2.36
36.5	3.45	0.00568	0.00323	-2.25
39.5	5.54	0.00913	0.00320	-2.04
41.0	5.81	0.00957	0.00318	-2.02
42.5	6.50	0.01072	0.00317	-1.97
44.5	7.51	0.01238	0.00315	-1.91
47.0	9.29	0.01532	0.00312	-1.81

 

Vapour Pressure Results: Run 2

Temperature (°C)	Mass Difference (μg)	Vapour Pressure (Pa)	1/Temperature (1/K)	Log Vapour Pressure
29.0	1.51	0.00249	0.00331	-2.60
31.0	1.92	0.00316	0.00329	-2.50
32.5	2.01	0.00332	0.00327	-2.48
34.0	2.36	0.00389	0.00326	-2.41
35.5	3.17	0.00523	0.00324	-2.28
37.5	3.64	0.00600	0.00322	-2.22
39.5	4.49	0.00740	0.00320	-2.13
41.0	5.50	0.00906	0.00318	-2.04
42.5	6.43	0.01060	0.00317	-1.97
43.5	7.74	0.01277	0.00316	-1.89
45.5	10.22	0.01685	0.00314	-1.77
47.5	14.09	0.02323	0.00312	-1.63

 

Vapour Pressure Results: Run 3

Temperature (°C)	Mass Difference (μg)	Vapour Pressure (Pa)	1/Temperature (1/K)	Log Vapour Pressure
26.5	1.32	0.00217	0.00334	-2.66
29.0	1.05	0.00172	0.00331	-2.76
30.5	1.30	0.00214	0.00329	-2.67
32.0	1.66	0.00274	0.00328	-2.56
34.0	1.84	0.00303	0.00326	-2.52
35.5	2.40	0.00396	0.00324	-2.40
38.0	3.72	0.00613	0.00321	-2.21
39.5	4.72	0.00779	0.00320	-2.11
41.5	5.57	0.00919	0.00318	-2.04
43.0	6.89	0.01136	0.00316	-1.94
44.5	8.21	0.01353	0.00315	-1.87
46.0	10.14	0.01672	0.00313	-1.78

 

	Run 1	Run 2	Run 3
Correlation	-0.9954	-0.9937	-0.9799
Slope	-4576	-4972	-5052
Intercept	12.52	13.81	14.02
Log Vp at 25 °C	-2.82	-2.86	-2.92
Vapour pressure at 25 °C	1.5 x 10^-3	1.36 x 10^-3	1.19 x 10^-3

The mean vapour pressure at 25 ºC was 1.4 x 10^-3 Pa.

Henry’s Law constant for the test material can then be estimated from the vapour pressure and water solubility data according to the equation:

 

H = P / s

 

H = Henry’s Law constant (Pa.m^3.mol^-1)

P = Vapour pressure (Pa)

s = Water solubility (mol m^-3)

 

At 20 °C, P = 7.1 x 10^-4 Pa

s = (0.8804 / 214.6) x 1 000 mol m^-3

 

Therefore, Henry’s Law constant, H = 1.7 x 10^-4 Pa.m^3.mol^-1

Conclusions:

Under the conditions of the study, the vapour pressure of the test material was found to be 1.4 x 10^-3 Pa at 25 °C. The volatility of the test material was estimated as Henry’s Law constant to be 1.7 x 10^-4 Pa.m^3.mol^-1.

Executive summary:

The vapour pressure of the test material was assessed according to OECD Test Guideline 104 and EU Method A.4. and in compliance with GLP using a vapour pressure balance.

A check on the stability of the test material at elevated temperatures was performed by differential scanning calorimetry. No evidence of decomposition occurred below 90 ºC.

The microbalance was calibrated with a NAMAS calibrated 1 mg weight. It was found that 1 μg produced a deflection of 2.87 x 10^-03 V.

A quantity of test material (0.12 g) was added to the furnace. The apparatus was then assembled and evacuated to a pressure of less than 2 x 10^-05 Torr (3 x 10^-3 Pa).

After stabilisation at a given temperature, the shutter was opened to allow a stream of vapour to impact upon one balance pan. The temperature and pan deflection were recorded on a chart recorder.

The trace obtained enabled the calculation of mass difference. The furnace temperature was then raised in steps of 0.5 to 3.0 ºC and further measurements taken.

Three runs were performed between temperatures of 26 and 47.5 ºC. The same sample was used for each test, with the pressure being kept at less than 1 x 10^-5 Torr (2 x 10^-3 Pa) throughout.

Under the conditions of the study, the vapour pressure of the test material was found to be 1.4 x 10^-3 Pa at 25 °C. The volatility of the test material was estimated as Henry’s Law constant to be 1.7 x 10^-4 Pa.m^3.mol^-1.

Reference 2

Endpoint:

vapour pressure

Type of information:

experimental study

Adequacy of study:

key study

Study period:

11 April 1990 to 20 August 1990

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 104 (Vapour Pressure Curve)

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method A.4 (Vapour Pressure)

Deviations:

no

Qualifier:

according to guideline

Guideline:

other: EPA FIFRA Subdivision D § 63-9

Deviations:

no

GLP compliance:

yes

Type of method:

static method

Key result

Test no.:

#1

Temp.:

20 °C

Vapour pressure:

0.093 Pa

Remarks on result:

other: Theoretical determination

Key result

Test no.:

#1

Temp.:

25 °C

Vapour pressure:

0.164 Pa

Remarks on result:

other: Theoretical determination

The vapour pressure was not measurable (< 10 Pa) at 343 K (70 °C) thus the vapour pressure for the test material at 293 and 298 K (20 and 25 °C) is < 10 Pa.

Using the theoretical boiling point of the test material (approx 280 °C) the vapour pressure was estimated from a graph correlating the boiling point at standard pressure for the particular class of chemicals. Using this theoretical approach, the estimated vapour pressures of the test material at 20 and 25 °C (293 and 298 K) are 0.093 Pa and 0.164 Pa respectively.

Conclusions:

Under the conditions of the study the estimated vapour pressures of the test material at 20 and 25 °C (293 and 298 K) are 0.093 Pa and 0.164 Pa respectively.

Executive summary:

The vapour pressure of the test material was assessed according to OECD Method 104, EEC Method A4, EPA FIFRA Subdivision D § 63-9 and in compliance with GLP.

The vapour pressure was not measurable by the static measurement procedure (< 10 Pa) at 343 K (70 °C) thus the vapour pressure for the test material at 293 and 298 K (20 and 25 °C) is < 10 Pa. Using the theoretical boiling point of the test material (approx 280 °C) the vapour pressure was estimated from a graph correlating the boiling point at standard pressure for the particular class of chemicals.

Under the conditions of the study the estimated vapour pressure of the test material at 20 and 25 °C (293 and 298 K) are 0.093 Pa and 0.164 Pa respectively.

Reference 3

Endpoint:

vapour pressure

Type of information:

experimental study

Adequacy of study:

key study

Study period:

15th April 1994 to 17th June 1994

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 104 (Vapour Pressure Curve)

Version / remarks:

12th May 1981

Deviations:

no

Qualifier:

according to guideline

Guideline:

other: EPA subdivision D 63-9

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Type of method:

gas saturation method

Key result

Test no.:

#1

Temp.:

50 °C

Vapour pressure:

0.034 Pa

Key result

Test no.:

#2

Temp.:

50 °C

Vapour pressure:

0.021 Pa

Key result

Test no.:

#3

Temp.:

50 °C

Vapour pressure:

0.032 Pa

Key result

Test no.:

#1

Temp.:

35 °C

Vapour pressure:

0.006 Pa

Key result

Test no.:

#2

Temp.:

35 °C

Vapour pressure:

0.004 Pa

Key result

Test no.:

#3

Temp.:

35 °C

Vapour pressure:

0.006 Pa

Key result

Test no.:

#1

Temp.:

20 °C

Vapour pressure:

0 Pa

Key result

Test no.:

#2

Temp.:

20 °C

Vapour pressure:

0 Pa

Key result

Test no.:

#3

Temp.:

20 °C

Vapour pressure:

0 Pa

Key result

Vapour pressure:

0.029 Pa

Remarks on result:

other: Mean value

Recovery Test

The trapping and extraction efficiency have been checked under the chosen experimental conditions simulating a vapour pressure of about 1.6 x 10^-2 and 3.8 x 10^-2 Pa. The test material was almost exclusively collected in the first trap and the recovery values calculated for the two tests performed were found to be about 98 % and 96 %.

 

Preliminary Tests

The vapour pressures obtained at 50 °C varied from 2.64 x 10^-2 to 2.26 x 10^-2 Pa when the gas flow rate varied from 1 to 0.5 L/min. The variation was within the repeatability given for the gas saturation method (10 to 30 %). Therefore at 1 mL/min the carrier gas is assumed to be saturated and this flow rate was retained for the other determinations.

The preliminary tests also showed that nearly all of the test material vapour was collected in the first trap.

 

Stability of the Test Material in the Column

The purity value of the test material was found to be 991 g/kg when the material was recovered from the column. The initial purity value was 1 000 g/kg, the small differences between the various values are not significant and do not affect the integrity of this study. The chromatographic profile obtained with the test material from one of the column shows no significant difference with the original chromatographic profile.

 

Vapour Pressure Curve

From the data obtained at three temperatures a vapour pressure curve was calculated.

The values found for the constants of this Clausius Clapeyron equation are used to calculate the vapour pressure at 25 °C:

 

Ps = 6.4 x 10^-4 Pa.

Vapour Pressure

T = 50 °C	Test 1	Test 2	Test 3
Vapour pressure in Pa	3.36 x 10 ^-2	2.09 x 10 ^-2	3.24 x 10 ^-2

Mean value (Pa): 2.90 x 10^-2

RSD (%): 24

 

T = 35 °C	Test 1	Test 2	Test 3
Vapour pressure in Pa	5.68 x 10 ^-3	4.14 x 10 ^-3	5.54 x 10 ^-3

Mean value (Pa): 5.12 x 10^-3

RSD (%): 17

 

T = 20 °C	Test 1	Test 2	Test 3
Vapour pressure in Pa	3.13 x 10 ^-4	1.64 x 10 ^-4	2.10 x 10 ^-4

Mean value (Pa): 2.29 x 10^-4

RSD (%): 33

Conclusions:

Under the conditions of the study the vapour pressure of the test material at 25 °C was calculated to be 6.4 x 10^-4 Pa.

Executive summary:

The vapour pressure of the test material was assessed according to OECD Test Guideline 104 and in compliance with GLP using the gas saturation method.

The stability of the test material mixed with the Raschig rings was checked at the end of all the tests by HPLC analysis. Three experiments were conducted at a flow rate of about 1 L/min at 50 °C. Three experiments were conducted at a flow rate of about 1 L/min at 35 °C. Three experiments were conducted at a flow rate of about 1 L/min at 20 °C. The vapour pressure was calculated using the Clausius Clapeyron equation.

The vapour pressures obtained at 50 °C varied from 2.64 x 10^-2 to 2.26 x 10^-2 Pa when the gas flow rate varied from 1 to 0.5 L/min. The variation was within the repeatability given for the gas saturation method (10 to 30 %). Therefore at 1 mL/min the carrier gas is assumed to be saturated and this flow rate was retained for the other determinations.

The preliminary tests showed that nearly all of the test material vapour was collected in the first trap. From the data obtained at three temperatures a vapour pressure curve was calculated. The values found for the constants of the Clausius Clapeyron equation are used to calculate the vapour pressure at 25 °C.

From the data on the water solubility at 20 °C and the vapour pressure at 20 °C, the calulated Henry's law constant is equal to 5.7 x 10 ^-05 Pa m^3 mol^-1 at 20 °C.

Under the conditions of the study the vapour pressure of the test material at 25 °C was calculated to be 6.4 x 10^-4 Pa.

Reference 4

Endpoint:

vapour pressure

Type of information:

experimental study

Adequacy of study:

supporting study

Study period:

2 February 1988

Reliability:

4 (not assignable)

Rationale for reliability incl. deficiencies:

documentation insufficient for assessment

Qualifier:

no guideline followed

Principles of method if other than guideline:

The determination of the vapour pressure was carried out by thermo-gravimetric method based on evaporation rates.

GLP compliance:

not specified

Type of method:

other: Thermo-gravimetric method based on evaporation rates.

Key result

Temp.:

20 °C

Vapour pressure:

>= 0 mBar

Key result

Temp.:

25 °C

Vapour pressure:

>= 0 mBar

Determination of Evaporation Rates VT

Measuring Number	Measuring Temperature		1/T2 (K^-1)	Measuring Time (h)	Weight Loss (mg)	Evaporation Rate VT (mol/cm^2 x h)	IgVT (mol/cm^2 x h)
	T1 (°C)	T2 (K)
1740	54.0	327.15	3.057x10^-3	14.00	1.074	4.770x10^-8	-7.3215
1741	51.1	324.36	3.084x10^-3	8.67	0.446	3.200x10^-8	-7.4949
1742	46.6	319.75	3.127x10^-3	15.33	0.386	1.565x10^-8	-7.8055
1743	41.9	315.05	3.174x10^-3	8.67	0.088	6.314x10^-8	-8.1977
1744	35.8	308.95	3.237x10^-3	40.00	0.150	2.332x10^-8	-8.6323

For calculation purposes the temperature readings T1 in °C are converted to the absolute temperatures T2 and inserted into equation 1.

Linear relationship between lgVT and 1/T (Equation (1)):

Coefficient A = 15.32

Coefficient B (slope) = -7400.73

Degree of precision: 99.9 %

 

Calculation of Vapor Pressure

Temperature (°C)	Vapor Pressure (mbar)
20	4.0 x 10^-6
25	1.0 x 10^-5

Conclusions:

Under the conditions of the study the estimated vapour pressures of the test material at 20 and 25 °C are 4.0 x 10^-6 and 1.0 x 10^-5 mbar respectively.

Executive summary:

The determination of the vapour pressure was carried out by thermo-gravimetric method based on evaporation rates.

Under the conditions of the study the estimated vapour pressures of the test material at 20 and 25 °C are 4.0 x 10^-6 and 1.0 x 10^-5 mbar respectively.

Description of key information

Comb (2000b)

Under the conditions of the study, the vapour pressure of the test material was found to be 1.4 x 10^-3 Pa at 25 °C. The volatility of the test material was estimated as Henry’s Law constant to be 1.7 x 10^-4 Pa.m^3.mol^-1.

O'Connor (1990)

Under the conditions of the study the estimated vapour pressure of the test material at 20 and 25 °C (293 and 298 K) are 0.093 Pa and 0.164 Pa respectively.

Gomez (1994)

Under the conditions of the study the vapour pressure of the test material at 25 °C was calculated to be 6.4 x 10^-4 Pa.

Supporting Study: Gückel (1998)

Under the conditions of the study the estimated vapour pressures of the test material at 20 and 25 °C are 4.0 x 10^-6 and 1.0 x 10^-5 mbar respectively.

Key value for chemical safety assessment

Vapour pressure:

0.001 Pa

at the temperature of:

25 °C

Additional information

Comb (2000b)

The vapour pressure of the test material was assessed according to OECD Test Guideline 104 and EU Method A.4. and in compliance with GLP using a vapour pressure balance. The study was awarded a reliability score of 1 in accordance with the criteria set forth by Klimisch et al. (1997).

A check on the stability of the test material at elevated temperatures was performed by differential scanning calorimetry. No evidence of decomposition occurred below 90 ºC.

The microbalance was calibrated with a NAMAS calibrated 1 mg weight. It was found that 1 μg produced a deflection of 2.87 x 10^-03 V.

A quantity of test material (0.12 g) was added to the furnace. The apparatus was then assembled and evacuated to a pressure of less than 2 x 10^-05 Torr (3 x 10^-3 Pa).

After stabilisation at a given temperature, the shutter was opened to allow a stream of vapour to impact upon one balance pan. The temperature and pan deflection were recorded on a chart recorder.

The trace obtained enabled the calculation of mass difference. The furnace temperature was then raised in steps of 0.5 to 3.0 ºC and further measurements taken.

Three runs were performed between temperatures of 26 and 47.5 ºC. The same sample was used for each test, with the pressure being kept at less than 1 x 10^-5 Torr (2 x 10^-3 Pa) throughout.

Under the conditions of the study, the vapour pressure of the test material was found to be 1.4 x 10^-3 Pa at 25 °C. The volatility of the test material was estimated as Henry’s Law constant to be 1.7 x 10^-4 Pa.m^3.mol^-1.

O'Connor (1990)

The vapour pressure of the test material was assessed according to OECD Method 104, EEC Method A4, EPA FIFRA Subdivision D § 63-9 and in compliance with GLP. The study was awarded a reliability score of 1 in accordance with the criteria set forth by Klimisch et al. (1997).

The vapour pressure was not measurable by the static measurement procedure (< 10 Pa) at 343 K (70 °C) thus the vapour pressure for the test material at 293 and 298 K (20 and 25 °C) is < 10 Pa. Using the theoretical boiling point of the test material (approx 280 °C) the vapour pressure was estimated from a graph correlating the boiling point at standard pressure for the particular class of chemicals.

Under the conditions of the study the estimated vapour pressure of the test material at 20 and 25 °C (293 and 298 K) are 0.093 Pa and 0.164 Pa respectively.

Gomez (1994)

The vapour pressure of the test material was assessed according to OECD Test Guideline 104 and in compliance with GLP using the gas saturation method. The study was awarded a reliability score of 1 in accordance with the criteria set forth by Klimisch et al. (1997).

The stability of the test material mixed with the Raschig rings was checked at the end of all the tests by HPLC analysis. Three experiments were conducted at a flow rate of about 1 L/min at 50 °C. Three experiments were conducted at a flow rate of about 1 L/min at 35 °C. Three experiments were conducted at a flow rate of about 1 L/min at 20 °C. The vapour pressure was calculated using the Clausius Clapeyron equation.

The vapour pressures obtained at 50 °C varied from 2.64 x 10^-2 to 2.26 x 10^-2 Pa when the gas flow rate varied from 1 to 0.5 L/min. The variation was within the repeatability given for the gas saturation method (10 to 30 %). Therefore at 1 mL/min the carrier gas is assumed to be saturated and this flow rate was retained for the other determinations.

The preliminary tests showed that nearly all of the test material vapour was collected in the first trap. From the data obtained at three temperatures a vapour pressure curve was calculated. The values found for the constants of the Clausius Clapeyron equation are used to calculate the vapour pressure at 25 °C.

From the data on the water solubility at 20 °C and the vapour pressure at 20 °C, the calulated Henry's law constant is equal to 5.7 x 10 ^-05 Pa m^3 mol^-1 at 20 °C.

Under the conditions of the study the vapour pressure of the test material at 25 °C was calculated to be 6.4 x 10^-4 Pa.

Supporting Study: Gückel (1998)

The determination of the vapour pressure was carried out by thermo-gravimetric method based on evaporation rates. The study was awarded a reliability score of 4 in accordance with the criteria set forth by Klimisch et al. (1997).

Under the conditions of the study the estimated vapour pressures of the test material at 20 and 25 °C are 4.0 x 10^-6 and 1.0 x 10^-5 mbar respectively.