(2,6-xylyloxy) acetic acid

Hydrolysis

Administrative data

Endpoint:

hydrolysis

Type of information:

experimental study

Adequacy of study:

key study

Study period:

June 16-23 1999

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Study carried out in accordance with method C7 of commission directive 92/69/EEC and in accordance with GLP. The test material was well characterised

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1999

Report date:

1999

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

EU Method C.7 (Degradation: Abiotic Degradation: Hydrolysis as a Function of pH)

GLP compliance:

yes

Test material

Test material information

Constituent 1

Reference substance name:

-

EC Number:

430-910-7

EC Name:

-

Cas Number:

13335-71-2

Molecular formula:

Hill formula: C10H12O3 CAS formula: C10H12O3

IUPAC Name:

2-(2,6-dimethylphenoxy)acetic acid

Specific details on test material used for the study:

Details on properties of test surrogate or analogue material (migrated information):
acetylsalicylic acid

Study design

Analytical monitoring:

yes

Details on sampling:

The concentration of A-172245.0 in samples were determinded by a High performance Liquid Chromatography method with UV detection (HPLC-UV).

5 sets of calibration sampels were prepared corresponding to 5 nomila concentrations:
0.010, 0.025, 0.050, 0.075 and 0.1 g/L

samples were take at 0,2,4,6,24,48 and 120 hours after preparation

Buffers:

pH 4 buffer solution:
prepared by mixing 4.0 mL of 0.1 N NaOH with 500 mL of 0.1 M potassium hydrogen phthalate. MilliQ watr was added to reach a final volume of 1000 mL

pH 7 Buffer solution
Prepared by mixing 296.3 mL of 0.1 N NaOH with 500 mL of 0.1 M potassium dihydrogen phosphate (Kh2PO4). MilliQ water was added to reach a final volume of 1000ml

pH 9 Buffer solution
Prepared by mixing 213.0 ml of 0.1 N NaOH with 500 ml of 0.1 M boric acid. MilliQ water was added to reach a final volume of 1000 mL.

weighted amounts of A-172245.0 (about 25 mg) were solubilized in appropiate volumetric flasks in each buffer solution (pH 4,7 and 9, 50 ml) obtaining concentrations of about 0.5 mg/mL

Details on test conditions:

performed at 50 C and pH 4,7 and 9

Duration of test

Duration of test 1

Duration:

120 h

pH:

4

Initial conc. measured:

>= 0.5 mg/L

Duration of test 2

Duration:

120 h

pH:

7

Initial conc. measured:

>= 0.5 mg/L

Duration of test 3

Duration:

120 h

pH:

9

Initial conc. measured:

>= 0.5 mg/L

Number of replicates:

five

Negative controls:

yes

Remarks:

buffer solution at pH 4,7,9

Results and discussion

Preliminary study:

For all 3 buffer solutions the A-172245.0 half life observed was higher than 2.4 hours. In addition, the results obtained in anlysis of the test samples at 120 hours indicated that the test substance degraded les tha 10%, suggesting that its half life cycle may be assumed to behigher than 1 year in all media assayed.

Test performance:

All concentrations assayed showed accuracy and precision values within the acceptance intervals of 85-115% and 0-15% respectively.

Transformation products:

not specified

Details on hydrolysis and appearance of transformation product(s):

no reference to transformation products

Dissipation DT50 of parent compound

Dissipation DT50 of parent compound 1

pH:

4

Temp.:

50 °C

DT50:

> 1 yr

Dissipation DT50 of parent compound 2

pH:

7

Temp.:

50 °C

DT50:

> 1 yr

Dissipation DT50 of parent compound 3

pH:

9

Temp.:

50 °C

DT50:

> 1 yr

Details on results:

An abiotic degradation study was carried out on A-172245.0 at three different pH values (4, 7 and 9) and at the temperature of 50 +/- 1 °C to evaluate the constant of hydrolysis and the half-life values. A Preliminary test was carried out to evaluate whether the half-life values were lower than 1 day or higher than 1 year for the three pH values. The degradation curves obtained in this test indicated that A-172245.0 was not significantly hydrolyzed in the conditions applied. On the basis of the data obtained, the degradation half-life was assumed to be higher than 1 year in the environment.

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Conclusions:

Test material is predicated to have a degradation half-life of longer than one year in conditions in the environment.