Isoleucine, N-(1-oxohexadecyl)-

Biodegradation in water: screening tests

Link to relevant study record(s)

Reference

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2009-08-04 to 2009-09-11

Reliability:

1 (reliable without restriction)

Qualifier:

according to guideline

Guideline:

OECD Guideline 301 F (Ready Biodegradability: Manometric Respirometry Test)

Deviations:

not specified

GLP compliance:

yes

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic, adapted

Details on inoculum:

Activated sludge from the municipal sewage treatment plant Reutlingen-West was washed 2 times with tap water and filtered (Liquid jet vacuum pump with Filter paper circles, Schleicher & Schuell); 1 g of the wet filtrate corresponded to approximately 60 mg suspended solids. Using a test volume of 164 mL, 65.6 mg of the filtrate were inserted per flask, corresponding to 24 mg suspended solids per litre.

Duration of test (contact time):

28 d

Initial conc.:

100.3 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation:

CO2 evolution

Details on study design:

The Manometric Respirometry Test is recommended for the determination of “ready biodegradability“ of Test Items, that are not inhibitory to bacteria at the chosen test concentration. The test is performed at a test temperature of 22 ± 2 °C under aerobic conditions in closed bottles with
automatic data registration.
Respirometric BOD-determination is carried out with CO2-absorption on soda lime. The test is recommended for water soluble Test Items as well as insoluble and volatile Test Items. The concentration of the Test Item is ca. 100 mg/L. The concentration of the Reference Item, Sodium-Benzoate, is ca. 100 mg/L. Biodegradability is expressed as the percentage oxygen uptake (corrected for blank uptake) of the Theoretical Oxygen Demand
(ThOD) or of the Chemical Oxygen Demand (COD) respectively

Dilution water:
Deionised water was aerated for 2 h with a membrane pump and allowed to stand for 0.5 h before usage. This water was used for
preparation of the mineral medium for the blanks and as dilution water for the Test Item and Reference Item.
Mineral medium:
The following stock solutions were prepared:
solution 1: KH2PO4 8.50 g/L
K2HPO4 21.75 g/L
Na2HPO4 x 2 H2O 33.40 g/L
NH4Cl 0.50 g/L
solution 2: CaCl2 x 2 H2O 27.50 g/L
solution 3: MgSO4 x 7 H2O 22.50 g/L
solution 4: FeCl3 x 6 H2O 0.25 g/L
The stock solutions were diluted in deionised water for preparation of the Mineral medium for test flasks 1 – 6 directly before the start of the test. 1 L of the Mineral medium included 10 mL of solution 1 and 1 mL of solutions 2 – 4.

Incubation:
28 days, stirred culture at 22 ± 2 °C in a Climatic exposure test cabinet

Test Item:
The Test Item is a granular solid, comprising 2 components:
Component 1: C16H32O2 (3 % by weight)
Component 2: C22H43NO3 (97 % by weight)
The Test Item was put directly into the test flasks.

- Flasks:
1: Test Item in Mineral medium + inoculum
2: Test Item in Mineral medium + inoculum
3: Mineral medium + inoculum (blank)
4: Mineral medium + inoculum (blank)
5: Reference Item in Mineral medium + inoculum
6: Test Item in Mineral medium, sterilised with 6 mL HgCl2/L (C HgCl2 = 10 g/L; abiotic control)

- Validity criteria:
Deviation of biodegradation of the parallel flasks with Test Item =< 20 %.
BOD of the blank controls £ 60 mg O2/L after 28 d.
Biodegradation of Reference Item > 60 % after 14 d.

- Calculations:
The oxygen uptake (mg) by the Test Item at a defined time (corrected for blank values at the same time) was divided by the amount of Test Item.

BOD = mg O2 uptake Test Item - mg O2 uptake inoculumblank / mg Test Item in the flask = mg O2 /mg Test Item

If abiotic degradation (oxygen uptake) was observed, these values would be subtracted and the result considered analogous to the blank values.
The percentage of biological degradation is calculated as follows:

% Biodegradation = BOD (mgO2/mg Test Item) / ThOD or COD (mgO2 /mg Test Item) x 100

Biodegradation of the Reference Item is calculated accordingly.
Determination of the 10 days window of both Test Item and Reference Item begins when the degree of biodegradation has reached 10 % of BOD. The degree of biodegradation achieved during the following 10 days forms the basis of the 10 days window value. According to OECD-Guideline 301 F a Test Item is deemed to be readily biodegradable if 60 % biodegradation are achieved during the 10 days window.
For the compound: CcHhClclNnNanaOoPpSs the Theoretical Oxygen Demand
(ThOD) with nitrification was calculated as follows:
ThODNO3 = 16 (2 c + 1/2 (h-cl) + 5/2 n + 3 s + 5/2 p + 1/2 na-o) / MW
The Theoretical Oxygen Demand (ThOD) without nitrification was calculated as
follows: ThODNH3 = 16 (2 c + 1/2 (h-cl-3n) + 3 s + 5/2 p + 1/2 na-o) / MW
where: MW = molecular weight

Reference substance:

benzoic acid, sodium salt

Test performance:

- Validity Criteria:
The validity criteria of OECD-Guideline 301 F are accomplished:
- Maximum BOD-difference in flasks 1 + 2 at the end of the test: 0 % (nominal value: =< 20 %.)
- Mean value of inoculum blank: 52.1 mg O2/L (nominal value: £ 60 mg O2/L)
- Biodegradation of Reference Item after 14 d: 78.3 % (nominal value: > 60 %)

Parameter:

% degradation (CO2 evolution)

Value:

68.1

Sampling time:

10 d

Remarks on result:

other: with nitrification:

Parameter:

% degradation (CO2 evolution)

Value:

72.2

Sampling time:

28 d

Remarks on result:

other: with nitrification

Parameter:

% degradation (CO2 evolution)

Value:

72.4

Sampling time:

10 d

Remarks on result:

other: without nitrification

Parameter:

% degradation (CO2 evolution)

Value:

76.8

Sampling time:

28 d

Remarks on result:

other: without nitrification

Results with reference substance:

Reference Item:
- Test concentration: 101.2 mg/L
- Theoretical Oxygen demand (ThOD): 1.67 mg O2/mg substance
- ThOD in flask 5: 168.5 mg O2/L
- BOD in flask 5 after 28 days: 191.0 mg O2/L (including blank)
- BODReference Item - BODinoculum blank: 138.9 mg O2/L
- Biodegradation after 14 days: 78.3 %
- Biodegradation after 28 days: 82.4 %
- 10 days window: 76.1 %

Biodegradability of Test Item with nitrification:

- Test concentration: 100.3 mg/L

- ThOD of Component 1; C16H32O2 (3%) of the Test Item: 2.88 mg O2/mg Test Item

- ThOD of Component 2; C22H43NO3 (97%) of the Test Item: 2.82 mg O2/mg Test Item

- ThOD in the test flasks: 282.86 mg O2/L

- BOD in flask 1 after 28 days: 259.0 mg O2/L (including blank)

- BOD in flask 2 after 28 days: 259.0 mg O2/L (including blank)

- mean value: 259.0 mg O2/L (including blank)

- maximum BOD-difference in flasks 1 + 2 at the end of the test (required: < 60 mg O2/L): 52.1 mg O2/L

- BOD in flask 6 after 28 days (abiotic degradation): 2.8 mg O2/L

- BODTest Item - BODinoculum blank - BODTest Item abiotic: 204.1 mg O2/L

- Biodegradation after 14 days: 69.2 %

- Biodegradation after 28 days: 72.2 %

- 10 days window: 68.1 %

Biodegradability of Test Item without nitrification:

- Test concentration: 100.3 mg/L

- ThOD of Component 1; C16H32O2 (3%) (3%) of the Test Item: 2.88 mg O2/mg Test Item

- ThOD of Component 2; C22H43NO3 (97%) of the Test Item: 2.65 mg O2/mg Test Item

- ThOD in the test flasks: 265.99 mg O2/L

- Biodegradation after 14 days: 73.6 %

- Biodegradation after 28 days: 76.8 %

- 10 days window: 72.4 %

The pH in the flasks 1 + 2 originally was 7.6 and was corrected to 7.3 by addition of 1N HCl at the beginning of the test. At the end of the test the pH in the flasks 1 + 2 was 7.3.

Validity criteria fulfilled:

yes

Interpretation of results:

readily biodegradable

Conclusions:

The Test Item 1893 JG of SEPPIC achieved 72 % biodegradation with nitrification in 28 days (10 days window: 68 %) and 77 % biodegradation without
nitrification in 28 days (10 days window: 72 %) in a Manometric Respirometry Test conducted according to OECD-Guideline 301 F.
The Test Item 1893 JG is therefore readily biodegradable.

Executive summary:

The Manometric Respirometry Test is recommended for the determination of “ready biodegradability“ of Test Items, that are not inhibitory to bacteria at the chosen test concentration. The test is performed at a test temperature of 22 ± 2 °C under aerobic conditions in closed bottles with automatic data registration. Respirometric BOD-determination is carried out with CO2- absorption on soda lime. The test is recommended for water soluble Test Items as well as insoluble and volatile Test Items. The concentration of the Test Item is ca. 100 mg/L. The concentration of the Reference Item, Sodium-Benzoate, is ca. 100 mg/L. Biodegradability is expressed as the percentage oxygen uptake (corrected for blank uptake) of the Theoretical Oxygen Demand (ThOD) or of the Chemical Oxygen Demand (COD) respectively.

The Test Item 1893 JG of SEPPIC achieved 72 % biodegradation with nitrification in 28 days (10 days window: 68 %) and 77 % biodegradation without nitrification in 28 days (10 days window: 72 %) in a Manometric Respirometry Test conducted according to OECD-Guideline 301 F. The Test Item 1893 JG is therefore readily biodegradable.

Description of key information

According to the OECD-Guideline 301 F (Manometric Respirometry Test), the Test Item 1893 JG of SEPPIC achieved 72 % biodegradation with nitrification in 28 days (10 days window: 68 %) and 77 % biodegradation without nitrification in 28 days (10 days window: 72 %)

Key value for chemical safety assessment

Biodegradation in water:

readily biodegradable

Type of water:

freshwater