2-Pentanone, O,O',O''-(ethenylsilylidyne)trioxime

Biodegradation in water: screening tests

Administrative data

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

weight of evidence

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Guideline study conducted under GLP

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2008

Report date:

2008

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

OECD Guideline 301 B (Ready Biodegradability: CO2 Evolution Test)

Test guideline 2

Qualifier:

according to guideline

Guideline:

EU Method C.4-C (Determination of the "Ready" Biodegradability - Carbon Dioxide Evolution Test)

GLP compliance:

yes (incl. QA statement)

Test material

Test material information

Constituent 1

Reference substance name:

-

EC Number:

484-470-6

EC Name:

-

Cas Number:

623-40-5

Molecular formula:

C5 H11 N O

IUPAC Name:

2-Pentanone, oxime

Constituent 2

Reference substance name:

2-Pentanone oxime

IUPAC Name:

2-Pentanone oxime

Test material form:

other: Colourless to pale yellow liquid

Study design

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic, adapted

Details on inoculum:

The source of test organism was activated sludge freshly obtained from a municipal sewage treatment plant: Waterschap de Maaskant, s-Hertogenbosch, The Netherlands, receiving predominantly domestic sewage. The freshly obtained sludge wask kept under continuous aeration until further treatment. The concentration of suspended solids was 4.4 g/l in the concentrated slkudge (infomration obtained from the municipal sewage treatment plant) Before use, the sludge was allowed to settle (83 minutes) and the liquid was decanted for use as inoculum at the amount of 10 ml/l of mineral medium.

Duration of test (contact time):

29 d

Initial test substance concentration

Initial conc.:

12 other:

Based on:

other: TOC/L

Parameter followed for biodegradation estimation

Parameter followed for biodegradation estimation:

CO2 evolution

Details on study design:

Pre-incubation medium:Mineral components, Milli-RO water (ca. 80% total volume) and inoculum (1% final volume) were added to each bottle. This mixture was aerated with synthetic air overnight to purge the system of CO2.
Type and number of bottles: Test suspension: containing test substance and inoculum (2 bottles). Inoculum blank: containing only inoculum (2 bottles). Positive control: containing reference substance and inoculum (1 bottle). Toxicity control: containing test substance, reference substance and
inoculum (1 bottle).
Preparation:The test substance and positive control were added to the bottles containing the microbial organisms and mineral components (ca. 80% of total volume). The volumes of suspensions were made up to 2 litres with MiIIi-RO water, resulting in the mineral medium described before. Three CO2-absorbers (bottles filled with 100 ml 0.0125 M Ba(OH), were connected in series to the exit air line of each test bottle.
Experimental CO2 production:The CO2 produced in each test bottle reacted with the barium hydroxide in the gas scrubbing bottle and precipitated outas barium carbonate. The amount of CO2 produced was determined by titrating the remaining Ba(OH), with 0.05 M standardized HCI (1 :20 dilution from 1 M HCI (Titrisol® ampul), Merck, Darmstadt, Germany).
Measurements:Titrations were made every second or third day during the first 10 days, and thereafter at least every fifth day until the 28th day. Each time the CO2-absorber nearest to the test bottle was removed for titration; each of the remaining two absorbers was moved one position in the direction of the test bottle. A new CO2-absorber was placed at the far end of the series. Phenolphthalein (1 % solution in ethanol, Merck, Darmstadt, Germany) was used as pH-indicator. On the 28th day, the pH of the test suspensions was measured and 1 ml of concentrated HCI (37%, Merck, Darmstadt,Germany) was added to each bottle. The bottles were aerated overnight to drive off CO2 present in the test suspension. The final titration was made on day 29.
Theoretical CO, production: The theoretical CO2 production was calculated from the molecular formula.
Measurements and recordings: pH- at the start of the test and on the 28th day. Temperature of medium: Continuously in a vessel with Milli-RO water in the same room. Electronic data capture: Observations/measurements in the study were recorded electronically using the following programme:
REES version 1.5 (REES scientific, Trenton, NJ, USA): Temperature.
Data evaluation: Relative degradation values were calculated from the cumulative CO2 production relative to the total expected CO2 production based on the total carbon content of the amount of test material present in the test bottles. A figure of more than 10% degradation was considered as significant. The relative degradation values were plotted versus time together with the relative degradation of the positive control. If applicable, the number of days is calculated from the attainment of 10% biodegradation until 60% biodegradation. Should this period be:s 10 days (1 O-day window), then the test substance is designated as readily biodegradable. Toxicity control: if less than 25% degradation (based on ThC02) occurred within 14 days, the test substance was assumed to be inhibitory. The total CO2 evolution in the inoculum blank was determined by the cumulative difference (in
ml of titrant) between the blank Ba(OH)2 traps and fresh Ba(OH)2.

Reference substance

Reference substance:

other: sodium acetate

Results and discussion

% Degradation

Parameter:

% degradation (CO2 evolution)

Value:

9

Sampling time:

28 d

BOD5 / COD results

Results with reference substance:

In the toxicity control more than 25% degradation occurred within 14 days (33%, based on ThC02). Therefore, the test substance was assumed not toinhibit microbial activity.

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Interpretation of results:

under test conditions no biodegradation observed

Conclusions:

2-Pentanone oxime (Methyl propylketoxime) was not readily biodegradable under the conditions of the modified Sturm test presently performed.