4-methylpentan-2-one oxime

Biodegradation in water: screening tests

Administrative data

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

key study

Study period:

04-06-2008 to 02-07-2008

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2008

Report date:

2008

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 302 B (Inherent biodegradability: Zahn-Wellens/EMPA Test)

Deviations:

no

GLP compliance:

yes

Test material

Test material information

Constituent 1

Reference substance name:

4-methylpentan-2-one oxime

EC Number:

203-298-2

EC Name:

4-methylpentan-2-one oxime

Cas Number:

105-44-2

Molecular formula:

C6H13NO

IUPAC Name:

4-methylpentan-2-one oxime

Test material form:

liquid

Specific details on test material used for the study:

SOURCE OF TEST MATERIAL
- Source and lot/batch No.of test material: 080301
- Expiration date of the lot/batch: not indicated
- Sample purity: 99.9%


STABILITY AND STORAGE CONDITIONS OF TEST MATERIAL
- Storage condition of test material: in the dark, at ambiant temperature, in the container in which it was received until required for testing

Study design

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic, non-adapted

Details on inoculum:

- Source of inoculum/activated sludge (e.g. location, sampling depth, contamination history, procedure): Activated sludge was obtained from Buckland Sewage Treatment Works, Newton Abbot, Devon, UK. This works treats sewage of predominantly domestic origin.
- Storage conditions: At the laboratory the activated sludge was kept aerated at room temperature and the pH maintained at approximately 7.
- Preparation of inoculum for exposure: The sludge was collected on the study start day. Before use the activated sludge was allowed to settle, the supernatant liquid decanted and the remaining sludge washed with test nutrient solution. Finally the supernatant was decanted and the total solids concentration determined on the remaining sludge.
- Pretreatment: no

Duration of test (contact time):

28 d

Initial test substance concentration

Initial conc.:

400 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation

Parameter followed for biodegradation estimation:

DOC removal

Details on study design:

TEST CONDITIONS
- Composition of medium: The test medium was made up according to the OECD 302 B guideline (Ref 1) and contained approximately the following nutrients per litre of deionised water: 85 mg of KH2PO4, 217.5 mg of K2HPO4, 334 mg of Na2HPO4.2H2O, 5 mg of NH4Cl, 22.5 mg of MgSO4.7H2O, 36.4 mg of CaCl2.2H2O, 0.25 mg of FeCl3.6H2O and 0.40 mg of EDTA (disodium salt).
- Additional substrate: no
- Test temperature: 20 +/- 2°C
- pH: 6.5 - 8.0
- pH adjusted: yes. After being made up to volume (1000 ml), the pH of each treatment was measured and adjusted to between 6.5 and 8.0 using 2 M sodium hydroxide or 2 M hydrochloric acid as appropriate.
- Aeration of dilution water: The flasks were provided with gentle aeration and stirred (magnetic stirrer) for 28 days
- Continuous darkness: The laboratory was in darkness, except for when readings or samples were taken.

TEST SYSTEM
- Culturing apparatus: not indicated
- Number of culture flasks/concentration:
* blank control (inoculum only): 2 replicates
* positive control (inoculum + 300 mg/l aniline): 2 replicates
* exposure vessel (inoculum + 400 mg/l MIBKO): 2 replicates
- Method used to create aerobic conditions: The flasks were provided with gentle aeration and stirred with a magnetic stirrer.
- Measuring equipment: not indicated
- Test performed in closed vessels due to significant volatility of test substance: no

SAMPLING
- Sampling frequency: 3 hours after the start of the test and on days 1, 2, 7, 14, 21 and 28 (the positive control vessels were not sampled on Days 1 and 2).
- Sampling method: not indicated
- Sample storage before analysis: not indicated

CONTROL AND BLANK SYSTEM
- Inoculum blank: yes, two replicates with only inoculum
- Toxicity control: no

Reference substance

Reference substance:

aniline

Results and discussion

Test performance:

The results for the positive control show that a minimum of 70% aniline biodegradation had been achieved within 14 days, confirming the viability of the activated sludge.
The results for methyl isobutyl ketoxime show that the maximum biodegradation in the Zahn Wellens test of 98% was achieved after 28 days incubation.
The test substance appears to satisfy the criteria for inherent biodegradation

% Degradation

Key result

Parameter:

% degradation (DOC removal)

Value:

98

Sampling time:

28 d

Details on results:

The results for methyl isobutyl ketoxime show that the maximum biodegradation in the Zahn Wellens test of 98% was achieved after 28 days incubation. The test substance appears to satisfy the criteria for inherent biodegradation

BOD5 / COD results

Results with reference substance:

The results for the positive control show that a minimum of 70% aniline biodegradation had been achieved within 14 days, confirming the viability of the activated sludge.

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Interpretation of results:

inherently biodegradable

Conclusions:

A 28-d ready biodegradability test (OECD 302B, Zahn-Wellens/EMPA test) using unadapted activated sludge from a predominantly domestic waste water treatment plant indicated that methyl isobutyl ketoxine (MIBKO) is inherently biodegradable under the conditions of the test (initial concentration of 400 mg/l). The test substance showed 98% biodegradation on day 28. The results of the test can be considered reliable without restriction.