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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:
Not stated
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
study well documented, meets generally accepted scientific principles, acceptable for assessment
Qualifier:
according to
Guideline:
other: BBA Merkblatt no. 55
Deviations:
yes
Remarks:
Test was stopped after 150 days rather than when 50 % of the test material had decomposed. This deviation complies with EPA Guideline 161-1
GLP compliance:
yes
Radiolabelling:
no
Analytical monitoring:
yes
Buffers:
- pH: 5, 7 and 9
- Type and final molarity of buffer:
- Composition of buffer:
pH 5: 0.1 mol/L potassium hydrogen phtalate and 0.05 mol/L sodium hydroxide
pH 7: 0.071 mol/L potassium hydrogen phosphate and 0.01 mol/L disodium hydrogen phosphate
pH 9: 0.1 mol/L boric acid, 0.1 mol/L potassium chloride and 0.1 mol/L sodium hydroxide
Details on test conditions:
TEST SYSTEM
- Type, material and volume of test flasks, other equipment used: closed, non-sterile, all glass vessels
- Sterilisation method: not applicable
- Lighting: none
- Measures taken to avoid photolytic effects: vessels kept in the dark
Duration:
150 d
Temp.:
22 °C
Initial conc. measured:
0.007 - 0.009 µg/L
Number of replicates:
2
Positive controls:
no
Negative controls:
no
Transformation products:
not measured
Key result
pH:
5
Temp.:
22 °C
DT50:
> 150 d
Key result
pH:
7
Temp.:
22 °C
DT50:
> 150 d
Key result
pH:
9
Temp.:
22 °C
DT50:
> 150 d
Details on results:
RECOVERIES OF TEST MATERIAL
- 7th September 1982: mean recovery 100 % (all pHs)
- 29th September 1982: mean recovery 102 % (all pHs)
- 7th December 1982: mean recovery 102.4 % (all pHs)
- 10th February 1983: mean recovery 100 % (all pHs)

Table 1: Results

Concentration of test material (µg/mL)
 Days after test start pH 5 pH 7 pH 9
 0 7.24 8.90 8.93
 16 7.16 8.55 8.68
 30 7.14 8.64* 8.65
 60 7.04 8.57 8.55
 90 7.20 8.58 8.30
 150 6.83 8.24 8.18*

* based on one value as the other was regarded as an outlier

The coefficient of variation was calculated from the duplicate determinations and equals 1.6 %. The decomposition was tested, using the first order model, and was significant for all three pH values.

Validity criteria fulfilled:
not specified
Conclusions:
Under the conditions of the test, the hydrolysis of the test material was determined to be >150 days and the test material is considered to be hydrolytically stable.
Executive summary:

In a GLP compliant hydrolysis conducted in accordance with sound scientific principles and an acceptable guideline (BBA Merkblatt no. 55), the hydrolysis of the test material was determined. Under the conditions of the test, the half-life of the test material was determined to be >150 days at pH 5, 7 and 9 and the test material is considered to be hydrolytically stable.

Description of key information

The test material was determined to be a have a half-life of >150 days at pH 5, 7 and 9 and is considered to be hydrolytically stable according to a study performed in line with recognised guideline BBA Merkblatt no. 55.

Key value for chemical safety assessment

Additional information

The key study (Buisman, 1988) was performed in line with GLP and a recognised guideline with a sufficient level of detail to assess the quality of the study. The study was performed to a good standard and was assigned a reliability score of 2 using the principle for assessing data quality as set out in Klimisch (1997) on the basis that the guideline followed was not a standardised guideline although sufficient for the purposes of this study.