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Environmental fate & pathways

Hydrolysis

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Reference
Endpoint:
hydrolysis
Type of information:
experimental study
Adequacy of study:
key study
Study period:
dec 2017 - dec 2018
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)
Qualifier:
according to guideline
Guideline:
OECD Guideline 111 (Hydrolysis as a Function of pH)
GLP compliance:
yes (incl. QA statement)
Specific details on test material used for the study:
Identity: Triazolone
Appearance: Off-white powder
Storage conditions: Room temperature (15 to 25°C), dark
Batch number: 0727/16
Purity: 99%
Expiry date: 28 April 2019
Date received: 28 April 2017
Radiolabelling:
no
Analytical monitoring:
yes
Details on sampling:
Preliminary test
The following procedure was carried out at each of pH 4, 7 and 9:

Aliquots (0.2 mL) of a stock solution of Triazolone in purified water (40 g/L) were added to separate Wheaton vials containing buffer solution (10 mL), which had been purged with nitrogen and pre-equilibrated at test temperature (50 ± 0.5°C).

The samples, of nominal concentration 800 mg/L, were placed in a 50°C oven in the dark until sampling was required (immediately, and then after 2.4, 24 and 163 hours).

At each sampling time, two samples were removed from the bath and an aliquot (1 mL) of each was diluted to volume (20 mL) with mobile phase for analysis by high performance liquid chromatography (HPLC).

Sample pH and incubation temperature were monitored over the period of the test.
Buffers:
Buffer solutions were prepared as follows:
pH 4: 0.2M aqueous potassium dihydrogen orthophosphate (550 mL) was mixed with
0.07M aqueous disodium hydrogen orthophosphate dodecahydrate (1250 mL) and purified water (3200 mL). The pH was adjusted to 4.0 ± 0.05 with orthophosphoric acid.
pH 7: 0.2M aqueous potassium dihydrogen orthophosphate (1250 mL) was mixed with
1M sodium hydroxide (150 mL) and purified water (3660 mL). The pH was adjusted to
7.0 ± 0.05 with 1M hydrochloric acid.
pH 9: 0.1M boric acid in 0.1M aqueous potassium chloride (2500 mL) was mixed with
1M sodium hydroxide (105 mL) and purified water (2395 mL). The pH was adjusted to
9.0 ± 0.05 with 1M hydrochloric acid or 1M sodium hydroxide, as required.
Duration:
120 h
pH:
4
Temp.:
50 °C
Initial conc. measured:
99.05 mg/L
Duration:
120 h
pH:
7
Temp.:
50 °C
Initial conc. measured:
99.05 mg/L
Duration:
120 h
pH:
9
Temp.:
50 °C
Initial conc. measured:
99.05 mg/L
Number of replicates:
in accordance to guidelines
Preliminary study:
yes
Transformation products:
no
Key result
pH:
4
Temp.:
25 °C
DT50:
> 1 yr
Type:
not specified
Key result
pH:
7
Temp.:
25 °C
DT50:
> 1 yr
Type:
not specified
Key result
pH:
9
Temp.:
25 °C
DT50:
> 1 yr
Type:
not specified

Standard concentration (mg/L)

Peak area

 

 

99.05

2907.9

79.24

2368.4

59.43

1794.8

39.62

1222.3

19.81

616.79

9.905

310.17

4.952

155.67

 

Ct (mg/L)

pH

t0h

t2.4h

t24h

t163h

 

Measured

Mean

Measured

Mean

Measured

Mean

Measured

Mean

 

 

 

 

 

 

 

 

 

4

558*, 809

809

808, 809

808

808, 825

817

796, 811

804

 

 

 

 

 

 

 

 

 

7

798, 801

799

813, 754

784

819, 800

809

799, 817

808

 

 

 

 

 

 

 

 

 

9

799, 802

801

798, 799

799

795, 801

798

805, 797

801

 

 

 

 

 

 

 

 

 

Validity criteria fulfilled:
yes
Conclusions:
Triazolone was determined to be hydrolytically stable under acidic, neutral and basic conditions.
Executive summary:

A study was performed to determine the rate of hydrolysis of Triazolone as a function of pH. The test was conducted in accordance with the preliminary test as described in Council Regulation (EC) No. 440/2008 (Method C.7) and the OECD Guidelines for Testing of Chemicals (Method 111).

The preliminary study showed that at each of pH 4, 7 and 9 and 50±0.5ºC, less than 10% hydrolysis had occurred after 5 days, equivalent to a half-life of greater than 1 year under environmental conditions (25°C). No further testing was considered necessary. Triazolone was determined to be hydrolytically stable under acidic, neutral and basic conditions.

Description of key information

Triazolone was determined to be hydrolytically stable under acidic, neutral and basic conditions.

Key value for chemical safety assessment

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

Additional information