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

Stability: thermal, sunlight, metals

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

stability: thermal, sunlight, metals, other

Type of information:

experimental study

Adequacy of study:

supporting study

Study period:

14 November 1990 to 26 February 1991

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Qualifier:

according to guideline

Guideline:

other: EPA/FIFRA Pesticide Assessment Guidelines - subdivision D - Product Chemistry § 6-13.

Deviations:

no

GLP compliance:

yes

Test substance thermally stable:

yes

Remarks:

The test material and its three major impurities were not significantly affected by storage at the selected temperatures.

Key result

Operating temp.:

>= 21 - <= 54 °C

Sublimation:

not determined

Transformation products:

no

Test substance stable to sunlight:

yes

Test substance stable to metals / metal ions:

yes

Analytical Results

- Thermal stability: It was found that the test material and its three major impurities were not significantly affected by storage at the selected temperatures. The purity of the main compound was found to increase slightly due to the degradation of some of the major impurities, whose concentrations fell by between 0 and 10%. The concentrations of the minor reported impurities also changed, several of these increasing by as much as 80 %, but because they were at such low levels, they did not affect the overall results.

As no higher purity sample was available, the technical grade compound supplied was used as its own standard. Also, as no retention information or standard samples were available for the known impurities contained in the compound, none of the impurity peaks found could be positively identified.

 

- Stability to light: It was found that the test material was not significantly affected by exposure to light although its three major impurities degraded by between 7 and 10 %, causing the test material concentration to rise slightly over the course of the test. The concentrations of the minor impurities changed by between -33 and +72 %, but because these were at levels of around 0.1 %, this did not affect the overall results.

Once again, none of the impurities could be identified due to lack of retention data and standards of the impurities.

 

- Stability to metals: It was found that the addition of the metals aluminium, tin and iron had no effect on the endothermic transitions of the test material and produced no additional transitions in the compound.

Summary of Mean Results for Thermal and Light Stability Test.

		Stability Test
		Thermal			Sunlight
	Time	Ambient	21 °C	54 °C	Ambient	Ambient
Substance	Temperature	0 Days	14 Days	14 Days	0 Hours	48 Hours
Test material	Retention time (min)	16.05	16.52	16.59	16.31	15.53
	Peak % and purity	96.88	96.91	96.99	96.83	97.04
Impurity No. 3	Retention time (min)	4.84	4.97	4.98	4.89	4.79
	Peak % and purity	0.16	0.13	0.11	0.12	0.12
Impurity No. 6	Retention time (min)	6.67	6.86	6.88	6.74	6.54
	Peak % and purity	0.07	0.09	0.10	0.07	0.12
Impurity No. 7	Retention time (min)	8.58	8.79	8.82	8.67	8.37
	Peak % and purity	0.25	0.24	0.25	0.26	0.24
Impurity No.8	Retention time (min)	9.07	9.27	9.30	9.17	8.83
	Peak % and purity	0.44	0.40	0.40	0.42	0.38
Impurity No. 11	Retention time (min)	11.07	11.36	11.41	11.23	10.80
	Peak % and purity	1.81	1.78	1.80	1.86	1.67
Impurity No. 13	Retention time (min)	13.48	13.84	13.92	13.67	13.06
	Peak % and purity	0.06	0.11	0.09	0.07	0.08
Impurity No. 14	Retention time (min)	14.95	15.35	15.40	15.18	14.46
	Peak % and purity	0.09	0.09	0.07	0.09	0.10
Impurity No. 18	Retention time (min)	Not found	Not found	Not found	Not found	20.47
	Peak % and purity					0.14
Impurity No. 19	Retention time (min)	21.23	21.83	21.91	21.59	21.90
	Peak % and purity	0.10	0.13	0.12	0.09	0.06

Original sample concentration: 1 200 µg/mL

Conclusions:

Under the conditions of the study the test material is thermally stable at 21 °C and 54 °C for two weeks, is photolytically stable and stable in the presence of the metals aluminium, tin or iron in an air atmosphere.

Executive summary:

The stability of the test material was assessed in relation to heat, metals and sunlight to comply with the EPA/FIFRA Pesticide Assessment Guidelines - Subdivision D - Product Chemistry § 6-13 and in compliance with GLP.

The test material was found to be thermally stable under the specified storage conditions. Its impurities were also found to be generally stable under these conditions.

On exposure to simulated sunlight, the test compound was found to be stable under the conditions of the test. The impurities present were found to have varying degrees of stability although none was present in a significant quantity.

The addition of small quantities of the metals aluminium, tin and iron was found to have no effect on the stability of the test compound between the temperatures of 25 and 150 °C.

Under the conditions of the study the test material is thermally stable at 21 °C and 54 °C for two weeks, is photolytically stable and stable in the presence of the metals aluminium, tin or iron in an air atmosphere.

Reference 2

Endpoint:

stability: thermal, sunlight, metals, other

Type of information:

experimental study

Adequacy of study:

key study

Study period:

02 February 1999 to 01 April 1999

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

EPA OPPTS 830.6313 (Stability to Sunlight, Normal and Elevated Temperature, Metals and Metal Ions)

Deviations:

no

GLP compliance:

yes

Test substance thermally stable:

yes

Key result

Operating temp.:

54 °C

Remarks on result:

other: The test material is stable in contact with aluminium, and zinc and their corresponding acetates, and at elevated temperatures when stored at 54 °C for 14 days. But it is not stable in contact with iron and iron acetate when stored at 54 °C for 14 days.

Sublimation:

not determined

Transformation products:

not measured

Test substance stable to sunlight:

not determined

Test substance stable to metals / metal ions:

ambiguous

Remarks:

The test material is stable in contact with aluminium, and zinc and their corresponding acetates, and at elevated temperatures when stored at 54 °C for 14 days. But it is not stable in contact with iron and iron acetate when stored at 54°C for 14 days.

The detector calibration was found to be linear over the range 0 to 100 mg/L of standard solutions in mobile phase with a regression coefficient of 0.9999.

Prior to storage the purity of the test material was found to be 96.7 %.

The results following storage with each metal, metal ion and at elevated temperature are listed below.

Storage	Active Ingredient Content (% w/w Test Material)
Aluminium	95.8
Aluminium acetate	94.5
Iron	76.3
Iron acetate	76.4
Zinc	94.8
Zinc acetate	95.2
Elevated temperature (54 °C)	95.9

The reaction of the test material with iron and iron acetate was indicated by a change in appearance of the samples. When in contact with iron the samples changed from a buff powder to a black/dark brown solid, and in contact with iron acetate the samples changed to a dark red solid.

Standard Calibration for the Test Material by HPLC.

Standard Concentration (mg/L)	Peak Area
30.26	409.6
60.52	823.3
90.79	1241.3
121.0	1621.4
151.3	2070.1

 

Linear regression (including x = 0, y = 0):

y = 16.6x – 1.26

r = 0.9999

x = Concentration

y = Peak area

Conclusions:

Under the conditions of the study the test material is stable in contact with aluminium and zinc and their corresponding acetates, and at elevated temperatures when stored at 54 °C for 14 days.
The test material is not stable in contact with iron and iron acetate when stored at 54 °C for 14 days.

Executive summary:

The stability of the test material was determined by storage in contact with metal/ metal ions at elevated temperature for 14 days in accordance with the EPA/OPPTS Series 830 Guideline 830.6313 and in compliance with GLP.

The stability was assessed by assaying the test material prior to and following contact with aluminium, iron, zinc and their corresponding acetate salts.

Samples of the test material were mixed with each of the powdered metals and their corresponding acetates in separate glass vials which were sealed, wrapped in aluminium foil to protect from light and then stored in a thermostatically controlled oven at 54 ± 2 °C for 14 days. Each sample was then quantitatively transferred to volumetric flasks with acetonitrile. A portion of 2 % aqueous acetic acid solution was added and the samples were sonicated for 10 minutes to ensure dissolution of the test material. The resulting samples were then diluted to volume with water. Portions of the suspensions were filtered and aliquots of the filtrates were diluted with mobile phase for analysis by HPLC relative to a bracketing standard solution.

The stability of the test material to elevated temperature was determined using a circular weight placed on top of the test material in a beaker in order to exert a downward pressure of 25 g/cm^2. The samples were then stored in a thermostatically controlled oven at 54 ± 2 °C for 14 days.

The reaction of the test material with iron and iron acetate was indicated by a change in appearance of the samples. When in contact with iron the samples changed from a buff powder to a black/dark brown solid, and in contact with iron acetate the samples changed to a dark red solid.

Under the conditions of the study the test material is stable in contact with aluminium and zinc and their corresponding acetates, and at elevated temperatures when stored at 54 °C for 14 days.

The test material is not stable in contact with iron and iron acetate when stored at 54 °C for 14 days.

Description of key information

Comb (2000c)

Under the conditions of the study the test material is stable in contact with aluminium and zinc and their corresponding acetates, and at elevated temperatures when stored at 54 °C for 14 days.

The test material is not stable in contact with iron and iron acetate when stored at 54 °C for 14 days.

Supporting Study: Cowlyn (1991)

Under the conditions of the study the test material is thermally stable at 21 °C and 54 °C for two weeks, is photolytically stable and stable in the presence of the metals aluminium, tin or iron in an air atmosphere.

Additional information

Comb (2000c)

The stability of the test material was determined by storage in contact with metal/ metal ions at elevated temperature for 14 days in accordance with the EPA/OPPTS Series 830 Guideline 830.6313 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 stability was assessed by assaying the test material prior to and following contact with aluminium, iron, zinc and their corresponding acetate salts.

Samples of the test material were mixed with each of the powdered metals and their corresponding acetates in separate glass vials which were sealed, wrapped in aluminium foil to protect from light and then stored in a thermostatically controlled oven at 54 ± 2 °C for 14 days. Each sample was then quantitatively transferred to volumetric flasks with acetonitrile. A portion of 2 % aqueous acetic acid solution was added and the samples were sonicated for 10 minutes to ensure dissolution of the test material.The resulting samples were then diluted to volume with water. Portions of the suspensions were filtered and aliquots of the filtrates were diluted with mobile phase for analysis by HPLC relative to a bracketing standard solution.

The stability of the test material to elevated temperature was determined using a circular weight placed on top of the test material in a beaker in order to exert a downward pressure of 25 g/cm^2. The samples were then stored in a thermostatically controlled oven at 54 ± 2 °C for 14 days.

The reaction of the test material with iron and iron acetate was indicated by a change in appearance of the samples. When in contact with iron the samples changed from a buff powder to a black/dark brown solid, and in contact with iron acetate the samples changed to a dark red solid.

Under the conditions of the study the test material is stable in contact with aluminium and zinc and their corresponding acetates, and at elevated temperatures when stored at 54 °C for 14 days.

The test material is not stable in contact with iron and iron acetate when stored at 54 °C for 14 days.

Supporting Study: Cowlyn (1991)

The stability of the test material was assessed in relation to heat, metals and sunlight to comply with the EPA/FIFRA Pesticide Assessment Guidelines - Subdivision D - Product Chemistry § 6-13 and in compliance with GLP. The study was awarded a reliability score of 2 in accordance with the criteria set forth by Klimisch et al. (1997).

The test material was found to be thermally stable under the specified storage conditions. Its impurities were also found to be generally stable under these conditions.

On exposure to simulated sunlight, the test compound was found to be stable under the conditions of the test. The impurities present were found to have varying degrees of stability although none was present in a significant quantity.

The addition of small quantities of the metals aluminium, tin and iron was found to have no effect on the stability of the test compound between the temperatures of 25 and 150 °C.

Under the conditions of the study the test material is thermally stable at 21 °C and 54 °C for two weeks, is photolytically stable and stable in the presence of the metals aluminium, tin or iron in an air atmosphere.