Mecoprop

Stability: thermal, sunlight, metals

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

stability: thermal, sunlight, metals, other

Remarks:

Stability: thermal, sunlight, metals

Type of information:

experimental study

Adequacy of study:

supporting study

Study period:

24 January 1991 to 29 April 1991

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 (incl. QA statement)

Test substance thermally stable:

yes

Operating temp.:

>= 20.5 - <= 21 °C

Operating temp.:

>= 53 - <= 54.5 °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 was not significantly affected by storage at the selected temperatures. A slight increase in concentration (less than 1 %) was noted. The major impurities generally decreased in concentration to varying degrees, with the exception of major impurity No. 14 which doubled in concentration at 21 °C.

 

Exposure to Sunlight

It was found that the test material was not significantly affected by exposure to light for a 48 hour period. A slight increase in concentration (less than 1 %) was noted. The major impurities generally decreased in concentration to varying degrees, with the exception of major impurity No. 14 which more than doubled in concentration.

 

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. No exothermic transitions were observed.

 

Summary of Thermal and Light Stability Tests (Original sample concentration: 100 - 150 mg/L)

	Stability Test
	Thermal			Sunlight
Temperature	Ambient	21 °C	54 °C	Ambient	Ambient
Time	0 Days	14 Days	14 Days	0 Hours	48 Hours
Test Material
Retention Time (min)	11.53	11.55	11.61	11.53	11.52
Peak % Purity	96.35	97.29	97.12	96.35	97.03
Impurity No. 1
Retention Time (min)	3.32	3.32	3.34	3.32	3.33
Concentration (%)	0.12	0.10	0.16	0.21	0.18
Impurity No. 3
Retention Time (min)	4.77	4.81	4.80*	4.77	4.78*
Concentration (%)	0.11	0.07	0.06	0.11	0.12
Impurity No. 4
Retention Time (min)	5.16	5.15	5.17	5.16	5.15
Concentration (%)	0.36	0.14	0.39	0.36	0.26
Impurity No. 6
Retention Time (min)	6.40	6.41	6.44	6.40	6.41
Concentration (%)	0.26	0.14	0.16	0.26	0.20
Impurity No. 8
Retention Time (min)	7.10	7.08	7.10	7.10	7.03
Concentration (%)	0.13	0.08	0.09	0.13	0.11
Impurity No. 9
Retention Time (min)	7.89	7.90	-	7.89	7.88
Concentration (%)	0.15	0.10	-	0.15	0.12
Impurity No. 10
Retention Time (min)	8.32	8.35	8.36	8.32	8.32
Concentration (%)	1.38	1.16	1.31	1.38	1.18
Impurity No. 12
Retention Time (min)	14.95	15.06	15.16	14.95	14.95*
Concentration (%)	0.36	0.29	0.20	0.36	0.26
Impurity No. 14
Retention Time (min)	16.27	16.28	16.24*	16.27	16.33
Concentration (%)	0.07	0.14	0.03	0.07	0.20
Impurity No. 18
Retention Time (min)	18.22	18.22	18.38	18.22	18.18
Concentration (%)	0.68	0.52	0.46	0.68	0.56

* Peak found at this retention time in only one sample of duplicate pair.

Detector Calibration (0 – 230 mg/L)

Standard Concentration (mg/L)	Peak Area
237.7	27 271
190.2	20 837
142.6	15 762
95.1	10 637
47.5	5 097
23.8	2 551

Linear regression (inc x = 0, y = 0): y = -189.5 + 113.3x r = 0.9995

Where:

x = Standard concentration (mg/L).

y = Peak area.

Conclusions:

Under the conditions of this study, the test material is stable up to 54 °C, to sunlight and to aluminium, tin and iron.

Executive summary:

The stability of the test material to heat, sunlight and metals was determined in accordance with the standardised guideline EPA OPPTS 830.6313 (Stability to Sunlight, Normal and Elevated Temperature, Metals and Metal Ions), under GLP conditions.

The thermal stability was determined at 21 and 54 °C over a period of 14 days. The stability was determined by measurement of the purity and impurity levels using HPLC with UV detection. A slight increase in the % purity (<1 %) of the major component was observed over the test period. The impurities measured decreased in concentration to varying degrees, the greatest reductions being in impurities 4 and 10, a reduction of 0.22 was observed for both impurities to 0.14 and 1.16 % respectively at 21 °C. It was noted that no reduction in these impurities was observed at 54 °C. Impurity 14 increased after 14 days at 21 °C to double its original value at T0 of 0.07 %. Again it was noted that this increase was not observed at 54 °C. Overall, the test material was considered to be thermally stable up to 54 °C.

The stability to sunlight was determined by exposing samples of the test material to artificial sunlight using the Heraeus Suntest CPS at the highest rating. The samples were exposed continuously for 48 hours. The irradiation range was 300 – 800 nm, the total exposure over the duration of the test was 24.5 x 10^-3Whm^-2. The stability of the samples was determined by measurement of the purity of the major component and the levels of impurities by HPLC with UV detection. Analysis of the samples after exposure showed a slight increase (<1 %) in the concentration of the major component, and a reduction to varying degrees of the impurities. The largest reduction being of impurity 10, which showed a reduction of 0.2 to 1.18 %. A slight increase of impurity 14 was observed from 0.07 to 0.2 %. Overall the test material was considered to be stable to sunlight.

Stability to metals was determined by exposing the test material to ground samples of tin, aluminium and iron and measuring the endothermic and exothermic effects by Differential Scanning Calorimetry (DSC). The DSC was carried out under air and nitrogen atmospheres using graphite DSC pans. The temperature range was room temperature to 150 °C. The addition of the metals had no effect on the endothermic transitions of the test material and produced no additional transitions. No exothermic transitions were observed. The test material is considered stable to metals between room temperature and 150 °C.

Under the conditions of this study, the test material is stable up to 54 °C, to sunlight and to aluminium, tin and iron.

Reference 2

Endpoint:

thermal stability

Type of information:

experimental study

Adequacy of study:

key study

Study period:

15 April 1999 to 23 June 1999

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 113 (Screening Test for Thermal Stability and Stability in Air)

Deviations:

no

Qualifier:

according to guideline

Guideline:

other: ASTM E 537-76

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Test substance thermally stable:

yes

Transformation products:

no

The initial investigation showed that endotherms occurred at approximately 95 and 280 °C. The first peak was attributed to the melting of the test material, while the second endotherm was considered to occur due to decomposition of the test material. At the end of this test the sample was observed to have decomposed leaving a trace of brown residue.

The observation of decomposition was consistent with the results of the boiling point test, in which the test material was observed to decompose above 260 °C without boiling.

The subsequent analysis over the temperature range of 80 to 160 °C, showed an endotherm with an extrapolated onset at approximately 93 °C. This peak was confirmed as being due to melting of the test material by reheating the test material under the same conditions and noting that the nature of the endotherm did not change. No other thermal behaviour was noted for the sample up to 150 °C.

Under the terms of OECD guideline the test material is stable at room temperature, because there was no decomposition or chemical change below 150 °C.

Conclusions:

Under the conditions of this study, the test material was found to be thermally stable at room temperature.

Executive summary:

The thermal stability of the test material was investigated in accordance with the standardised guidelines OECD 113 and ASTM E 537-76, under GLP conditions.

The thermal stability was investigated using differential scanning calorimetry.

The initial investigation showed that endotherms occurred at approximately 95 and 280 °C. The first peak was attributed to the melting of the test material, while the second endotherm was considered to occur due to decomposition of the test material. At the end of this test the sample was observed to have decomposed leaving a trace of brown residue. No other thermal behaviour was noted for the sample up to 150 °C.

Under the terms of OECD guideline the test material is stable at room temperature, because there was no decomposition or chemical change below 150 °C.

Under the conditions of this study, the test material was found to be thermally stable at room temperature.

Description of key information

Key Study: Comb (2000)

Under the conditions of this study, the test material was found to be thermally stable at room temperature.

Key Study: Cowlyn (1993)

Under the conditions of this study, the test material is stable up to 54 °C, to sunlight and to aluminium, tin and iron.

Additional information

Key Study: Comb (2000)

The thermal stability of the test material was investigated in accordance with the standardised guidelines OECD 113 and ASTM E 537-76, under GLP conditions. The study was awarded a reliability score of 1 in accordance with the criteria set forth by Klimisch et al. (1997).

The thermal stability was investigated using differential scanning calorimetry.

The initial investigation showed that endotherms occurred at approximately 95 and 280 °C. The first peak was attributed to the melting of the test material, while the second endotherm was considered to occur due to decomposition of the test material. At the end of this test the sample was observed to have decomposed leaving a trace of brown residue. No other thermal behaviour was noted for the sample up to 150 °C.

Under the terms of OECD guideline the test material is stable at room temperature, because there was no decomposition or chemical change below 150 °C.

Under the conditions of this study, the test material was found to be thermally stable at room temperature.

Key Study: Cowlyn (1993)

The stability of the test material to heat, sunlight and metals was determined in accordance with the standardised guideline EPA OPPTS 830.6313 (Stability to Sunlight, Normal and Elevated Temperature, Metals and Metal Ions), under GLP conditions. The study was awarded a reliability score of 1 in accordance with the criteria set forth by Klimisch et al. (1997).

The thermal stability was determined at 21 and 54 °C over a period of 14 days. The stability was determined by measurement of the purity and impurity levels using HPLC with UV detection. A slight increase in the % purity (<1 %) of the major component was observed over the test period. The impurities measured decreased in concentration to varying degrees, the greatest reductions being in impurities 4 and 10, a reduction of 0.22 was observed for both impurities to 0.14 and 1.16 % respectively at 21 °C. It was noted that no reduction in these impurities was observed at 54 °C. Impurity 14 increased after 14 days at 21 °C to double its original value at T0 of 0.07 %. Again it was noted that this increase was not observed at 54 °C. Overall, the test material was considered to be thermally stable up to 54 °C.

The stability to sunlight was determined by exposing samples of the test material to artificial sunlight using the Heraeus Suntest CPS at the highest rating. The samples were exposed continuously for 48 hours. The irradiation range was 300 – 800 nm, the total exposure over the duration of the test was 24.5 x 10^-3Whm^-2. The stability of the samples was determined by measurement of the purity of the major component and the levels of impurities by HPLC with UV detection. Analysis of the samples after exposure showed a slight increase (<1 %) in the concentration of the major component, and a reduction to varying degrees of the impurities. The largest reduction being of impurity 10, which showed a reduction of 0.2 to 1.18 %. A slight increase of impurity 14 was observed from 0.07 to 0.2 %. Overall the test material was considered to be stable to sunlight.

Stability to metals was determined by exposing the test material to ground samples of tin, aluminium and iron and measuring the endothermic and exothermic effects by Differential Scanning Calorimetry (DSC). The DSC was carried out under air and nitrogen atmospheres using graphite DSC pans. The temperature range was room temperature to 150 °C. The addition of the metals had no effect on the endothermic transitions of the test material and produced no additional transitions. No exothermic transitions were observed. The test material is considered stable to metals between room temperature and 150 °C.

Under the conditions of this study, the test material is stable up to 54 °C, to sunlight and to aluminium, tin and iron.