Methomyl

Stability: thermal, sunlight, metals

Link to relevant study record(s)

Reference

Endpoint:

stability: thermal, sunlight, metals, other

Type of information:

experimental study

Adequacy of study:

supporting study

Study period:

Completed October 1, 1989

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study without detailed documentation

Qualifier:

according to guideline

Guideline:

other: EPA 63-13

GLP compliance:

no

Specific details on test material used for the study:

Technical methomyl
X1179
Purity not provided

Test substance thermally stable:

yes

Remarks:

Stable at normal and elevated temperatures

Key result

Operating temp.:

ca. -6 °C

Remarks on result:

other: 98.2% active substance

Key result

Operating temp.:

ca. 25 °C

Remarks on result:

other: 98.2% X1179

Remarks:

two weeks, room temperature

Key result

Operating temp.:

ca. 45 °C

Remarks on result:

other: 97.5% X1179

Remarks:

2 weeks

Key result

Operating temp.:

<= 140 °C

Remarks on result:

other: No evidence of decomposition or exothermic behavior

Test substance stable to sunlight:

yes

Remarks:

Exposure of aqueous methomyl solutions at conc. of 10 ppm and 100 ppm to artificial sunlight yielded half-lives of appr. 5.5 days and 2 days, respectively

Test substance stable to metals / metal ions:

ambiguous

Remarks:

Dilute solutions of methomyl are stable in the presence of ferric chloride but degrade with an appr. half-life of 2 days in the presence of metallic iron.

Methomyl was stable in sterile distilled water for 30 days at PH 5 and PH 7, but decomposed with a half-live of 30 days at PH 9.

Conclusions:

Methomyl was stable at normal, reduced, and elevated temperatures. Its aqueous solution was stable in the presence of ferric chloride but was mildly corrosive to iron. Methomyl was stable in sterile distilled water for 30 days at PH 5 and PH 7, but decomposed with a half-live of 30 days at PH 9. Exposure of aqueous test substance solutions at concentrations of 10 ppm and 100 ppm to artificial sunlight (peak sensitivity at appr. 365 nm, and intensity equivalent to appr. half that of typical summer sunshine at noon) yielded half-lives of appr. 5.5 days and 2 days, respectively.

Executive summary:

Methomyl was stable at normal, reduced, and elevated temperatures.  Its aqueous solution was  stable in the presence of ferric chloride but was mildly corrosive to iron.  Methomyl was stable in sterile distilled water for 30 days at PH 5 and PH 7, but decomposed with a half-live of 30 days at PH 9.  Exposure of aqueous test substance solutions at concentrations of 10 ppm and 100 ppm to artificial sunlight (peak sensitivity at appr. 365 nm, and intensity equivalent to appr. half that of typical summer sunshine at noon) yielded half-lives of appr. 5.5 days and 2 days, respectively.

Description of key information

EPA 63-13

Additional information

Test substance stable at room and elevated temperatures. Its aqueous solutions are stable in the presence of ferric chloride but mildly corrosive to iron. Test substance is stable in sterile distilled water for 30 days at pH 5 and pH 7, but decomposes with a half-live of 30 days at PH 9. Aqueous solutions of test substance at concentrations of 10 ppm and 100 ppm decompose under artificial sunlight with half-lives of appr. 5.5 days and 2 days, respectively.