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

Additional physico-chemical information

Link to relevant study record(s)

Reference

Endpoint:

light stability

Type of information:

experimental study

Adequacy of study:

supporting study

Study period:

July 1991 to August 1991

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

study well documented, meets generally accepted scientific principles, acceptable for assessment

Qualifier:

no guideline followed

Principles of method if other than guideline:

The test material was illuminated with a Xenon lamp at 80 000 lux for 1, 4 and 24 hours. The concentration of unchanged test material was determined by HPLC and compared against analogous samples that had been stored in the dark over the same time periods.

GLP compliance:

yes

Illumination Time and Remaining Content in % of the Standard Solution

Sample	Illumination time (Incubation Time) (hours)	Lux	Remaining Active Ingredient in % of Standard Solution
			Replicate 1	Replicate 2	Mean
DP 1	1	0	99.9	99.6	99.8
DP 2	1	0	100.3	100.6	100.5
BP 1	1	80 000	97.5	97.7	97.6
BP 2	1	80 000	98.6	98.4	98.5
DP 1	4	0	102.5	102.9	102.7
DP 2	4	0	104.0	102.9	13.5
BP 1	4	80 000	89.7	89.8	89.8
BP 2	4	80 000	95.9	95.7	95.8
DP 1	24	0	99.4	99.6	99.5
DP 2	24	0	99.4	99.7	99.6
BP 1	24	80 000	53.4	53.3	53.3
BP 2	24	80 000	51.9	52.2	32.1

DP: Incubation in the dark.

BP: Illumination 80 000 lux.

The result of the regression analysis was:

m = -84.449626

b = 169.40947

r = -0.9963

The degradation function has the form of:

lg (% unchanged test material) = -84.449626 x (hours) + 169.40947

The degradation time for 80 % and 50 % remaining unchanged test material can be calculated using the aforementioned equation to produce:

lg 80 % = 1.9031 (degradation time = 8.7 hours)

lg 50 % = 1.699 (degradation time = 26 hours)

Conclusions:

Under the conditions of the study, the test material was found to have a light stability with a half life of 26 hours at a light intensity of 80 000 lux and a temperature of approximately 25 °C.

Executive summary:

The light stability of the test material was investigated in a GLP study during which the test material was illuminated with a Xenon lamp at 80 000 lux for 1, 4 and 24 hours. The concentration of unchanged test material was determined by HPLC and compared against analogous samples that had been stored in the dark over the same time periods.

Under the conditions of the study, the test material was found to have a light stability with a half life of 26 hours at a light intensity of 80 000 lux and a temperature of approximately 25 °C.

Description of key information

Light Stability: Redeker (1991)

The test material was found to have a light stability with a half life of 26 hours at a light intensity of 80 000 lux and a temperature of approximately 25 °C

Additional information

Light Stability: Redeker (1991)

The light stability of the test material was investigated in a GLP study during which the test material was illuminated with a Xenon lamp at 80 000 lux for 1, 4 and 24 hours. The concentration of unchanged test material was determined by HPLC and compared against analogous samples that had been stored in the dark over the same time periods.

Under the conditions of the study, the test material was found to have a light stability with a half life of 26 hours at a light intensity of 80 000 lux and a temperature of approximately 25 °C.