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Environmental fate & pathways

Hydrolysis

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Administrative data

Link to relevant study record(s)

Reference
Endpoint:
hydrolysis
Type of information:
experimental study
Adequacy of study:
key study
Study period:
2008-08-18 - 2008-10-21
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to guideline
Guideline:
EU Method C.7 (Degradation: Abiotic Degradation: Hydrolysis as a Function of pH)
Deviations:
no
GLP compliance:
yes (incl. QA statement)
Radiolabelling:
no
Analytical monitoring:
yes
Buffers:
Buffer pH 4:

10.2 g of Potassium hydrogen phthalate were weighed into a 1000 mL volumetric flask and Potassium hydrogen phthalate was dissolved in ca 800 mL water. After this step, 4 mL of 0.1M NaOH were added and the volumetric flask was filled up to its volume with water. pH = 4.00 (23.3 °C)

Buffer pH 7:

6.8 g of KH2PO4 were weighed into a 1000 mL volumetric flask and KH2PO4 was dissolved in ca 800 mL water. After this step, 296 mL of 0.1M NaOH were added and the volumetric flask was filled up to its volume with water.

pH = 7.00 (25.0 °C)

Buffer pH 9:

3.09 g of H3BO3 and 3.73 g of KC1 were weighed into a 1000 mL volumetric flask and substances were dissolved in ca 800 mL water. After this step, 213 mL of 0.1 M NaOH were added and the volumetric flask was filled up to its volume with water.

pH = 8.99 (25.0 °C)
Duration:
5 d
pH:
4
Initial conc. measured:
9.37 - 9.54 mg/L
Duration:
5 d
pH:
7
Initial conc. measured:
10.55 - 10.72 mg/L
Duration:
5 d
pH:
9
Initial conc. measured:
10.18 mg/L
Number of replicates:
2
Transformation products:
not measured
Key result
pH:
4
Temp.:
25 °C
DT50:
> 1 yr
Type:
(pseudo-)first order (= half-life)
Key result
pH:
7
Temp.:
25 °C
DT50:
> 1 yr
Type:
(pseudo-)first order (= half-life)
Key result
pH:
9
Temp.:
25 °C
DT50:
> 1 yr
Type:
(pseudo-)first order (= half-life)
Validity criteria fulfilled:
yes
Conclusions:
The preliminary testing performed at 50 ± 0.5 °C at three pH values: 4, 7 and 9 shows, that less than 10 % of the test substance was hydrolysed within 5-day period. According to the test guideline recommendation (Chapter 1.6.5.1. Preliminary test) the half-life time of hydrolysis can therefore be expected to be greater than one year at 25°C and no further testing is required.
Executive summary:

Hydrolysis as a function of pH of the test substance, 3-Methylpyrazol, was studied. The procedure was performed according to: Method C.7 - Degradation - Abiotic Degradation Hydrolysis as a Function of pH, Directive 92/69/EEC. Published in OJ No L 383 A, December 1992. The preliminary testing performed at 50 ± 0.5 °C at three pH values: 4, 7 and 9 shows, that less than 10 % of the test substance was hydrolysed within 5-day period. According to the test guideline recommendation the half-life time of hydrolysis can therefore be expected to be greater than one year at 25°C and no further testing is required.

Description of key information

The half-life for hydrolysis of 3-Methylpyrazole is greater than 1 year.

Key value for chemical safety assessment

Half-life for hydrolysis:
1 yr
at the temperature of:
25 °C

Additional information

The preliminary testing performed at 50 ± 0.5 °C at three pH values: 4, 7 and 9 shows, that less than 10 % of the test substance was hydrolysed within 5-day period. According to the test guideline recommendation the half-life time of hydrolysis can therefore be expected to be greater than one year at 25°C and no further testing is required.