Dimethyl methylphosphonate

Hydrolysis

Administrative data

Endpoint:

hydrolysis

Type of information:

experimental study

Adequacy of study:

other information

Reliability:

4 (not assignable)

Rationale for reliability incl. deficiencies:

other: Original reference not yet available (Reliability 1 is refered in HPV ICCA IUCLID)

Data source

Reference

Reference Type:

secondary source

Title:

Unnamed

Year:

2004

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

EPA OPPTS 835.2110 (Hydrolysis as a Function of pH)

Test guideline 2

Qualifier:

according to guideline

Guideline:

OECD Guideline 111 (Hydrolysis as a Function of pH)

GLP compliance:

yes

Test material

Test material information

Constituent 1

Reference substance name:

Dimethyl methylphosphonate

EC Number:

212-052-3

EC Name:

Dimethyl methylphosphonate

Cas Number:

756-79-6

Molecular formula:

C3H9O3P

IUPAC Name:

dimethyl methylphosphonate

Details on test material:

- Purity: 99.2 %
- Name of test material (as cited in study report): Fyrol DMMP
- Batch No.: 03114H0108

Study design

Details on test conditions:

In the preliminary study, the hydrolysis of Fyrol DMMP was evaluated in aqueous buffers at pH 4,7, and 9, over 5 days, at 50°C, at a concentration of 1000 mg/l. The aqueous buffers used at pH 4,7, and 9 were sodium acetate/acetic acid, potassium dihydrogen phosphate/sodium hydroxide, and potassium chloride/boric acid/sodium hydroxide, respectively. In the definitive test, the hydrolytic stability of Fyrol DMMP was evaluated at pH 9, at 31°, 40°C, and 50°C over 30 days. The amount of Fyrol DMMP was determined by extraction of duplicate samples with dichloromethane followed by analysis using gas chromatography with a flame-photometric detector. Calibration standards were prepared and used each time Fyrol DMMP levels were determined. The half-life at 25°C was calculated by extrapolation from the degradation rat constants obtained at the three elevated temperatures.

Results and discussion

Dissipation DT50 of parent compound

pH:

9

Temp.:

25 °C

DT50:

307 d

Type:

other: estimated from the result of a preliminary test

Details on results:

In the preliminary test, hydrolytic degradation of Fyrol DMMP was less than 10% at pH 4 and 7, at 50°C. Therefore the half-life of Fyrol DMMP at pH 4 and 7 was estimated to be greater than one year. In the definitive test conducted only at pH 9, the half-lives were calculated as 129 days at 31°C, 46.3 days at 40°C, and 11.8 days at 50°C. Linear regression analysis of the rate constants at each temperature showed the half-life at pH 9 and 25°C to be 307 days.