Oxaceprol

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:

2017-05-09 to 2017-07-05

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2017

Report date:

2017

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

OECD Guideline 301 E (Ready biodegradability: Modified OECD Screening Test)

Version / remarks:

1992

Deviations:

no

Test guideline 2

Qualifier:

according to guideline

Guideline:

EU Method C.4-D (Determination of the "Ready" Biodegradability - Manometric Respirometry Test)

Version / remarks:

2008

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Test material

Test material information

Constituent 1

Reference substance name:

Oxaceprol

EC Number:

251-780-6

EC Name:

Oxaceprol

Cas Number:

33996-33-7

Molecular formula:

C7H11NO4

IUPAC Name:

1-acetyl-4-hydroxy-L-proline

Test material form:

solid: crystalline

Specific details on test material used for the study:

SOURCE OF TEST MATERIAL
- Source and lot/batch No.of test material: Batch 6716-16E
- Expiration date of the lot/batch: Retest date: 2018-10-23
- Purity test date: 2016-11-17


STABILITY AND STORAGE CONDITIONS OF TEST MATERIAL
- Storage condition of test material: 20 °C +/- 5°C, in the desiccator in the dark
- Stability under test conditions: stable
- Solubility and stability of the test substance in the solvent/vehicle: soluble in water

Study design

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic, adapted

Details on inoculum:

- Source of inoculum/activated sludge (e.g. location, sampling depth, contamination history, procedure): Sewage treatment plant Bensheim, Germany

The aerobic activated sludge was washed by centrifugation and the supernatant liquid phase was decanted. The solid material was re-suspended in test water and centrifuged again. This procedure was done three times. An aliquot of the final sludge suspension was weighed, dried and the ratio of wet sludge to its dry weight was determined. Based on this ratio, calculated aliquots of washed sludge suspension, corresponding to 3.5 g dry material per litre were mixed with test water (see 6.5) and aerated overnight. This suspension was used for the experiment.

Duration of test (contact time):

28 d

Initial test substance concentration

Initial conc.:

ca. 0.1 g/L

Based on:

test mat.

Parameter followed for biodegradation estimation

Parameter followed for biodegradation estimation:

CO2 evolution

Details on study design:

TEST CONDITIONS
- Composition of medium: Reconstituted Test Water:
Analytical grade salts were added to pure water to prepare the following stock solutions:
a) 8.5 g KH2PO4, 21.75 g K2HPO4, 33.4 g Na2HPO4 x 2 H2O, 0.5 g NH4Cl filled up with pure water to 1000 mL volume; The pH-value was 7.4.
b) 11.25 g MgSO4 x 7 H2O filled up with pure water to 500 mL volume
c) 18.2 g CaCl2 x 2 H2O filled up with pure water to 500 mL volume
d) 0.125 g FeCl3 x 6 H2O filled up with pure water to 500 mL volume
In order to avoid precipitation of iron hydroxide in the stock solution d), one drop of concentrated HCl per litre was added before storage.
50 mL of stock solution a) and 5 mL of the stock solutions b) to d) were combined and filled up to a final volume of 5000 mL with pure water.
- Test temperature: 22°C +/- 1°C
- pH: 7.6 to 7.7 at start of test, 7.2 to 7.6 at end of test
- pH adjusted: no
- CEC (meq/100 g):
- Continuous darkness: yes

TEST SYSTEM
- Culturing apparatus: flask
- Number of culture flasks/concentration: 2
- Method used to create aerobic conditions: stirring
- Measuring equipment: BSB/BOD-Sensor-System
- Details of trap for CO2 and volatile organics if used: Evolved carbon dioxide was absorbed in an aqueous solution (45%) of potassium hydroxide.

SAMPLING
For N-containing test items as Oxaceprol, a correction for a potential uptake of oxygen by nitrification was made. For this reason, on exposure day 0 a sufficient aliquot was withdrawn from one bottle containing the test item and inoculum, from the inoculum control (after measurement of oxygen concentration) for analysis of nitrate-N and nitrite-N using Continuous Flow Analysis. At day 28 an aliquot from both inoculum controls, and both test item flasks was taken for analysis. Due to an increase in the concentration of nitrate-N and nitrite-N in the test bottles, the oxygen uptake by nitrification was calculated.
Specimen of a control and a test item treated flask was sampled at test start and stored deep frozen (-20°C ± 5°C) until nitrate-N and Nitrite-N determination was done. At test end, specimen of a control and test item treated groups were sampled and the nitrification was determined. For determination, undiluted extracts were used.
The nitrogen determination was done using a AA3 Continuous Flow Analyzer and equipment:
Pump: AA3
Autosampler: XY-2 / XY-3Sampler
Chemical Module: Control Modul Chemtray NO2 / NO3
Photometer: Wavelength 550 nm
Dilution Unity: Syringe Diluter 3
Eluent (in pure water): 0.1 M KCl
Software: AACE Vers 6.04GLP

CONTROL AND BLANK SYSTEM
- Inoculum blank: yes
- Procedure control: yes
- Toxicity control: sodium benzoate
- Other: Abiotic control (poisened with CuS04

Reference substance

Reference substance:

benzoic acid, sodium salt

Results and discussion

% Degradation

% Degradation 1

Key result

Parameter:

other: nitrate-N rate

Remarks:

Nitrogen is part of the molecular structure of the test item; therefore nitrification (ThODNO3) was considered for the evaluation of the results.

Value:

83

Sampling time:

28 d

% Degradation 2

Parameter:

other: ThOD NH4

Value:

108

Sampling time:

28 d

% Degradation 3

Parameter:

other: ThOD NO3

Value:

84

Sampling time:

28 d

BOD5 / COD results

Results with reference substance:

The reference item sodium benzoate was sufficiently degraded to 69% after 14 days and after 28 days of incubation.
The percentage biodegradation of the reference item confirms the suitability of the used aerobic activated sludge inoculum.

Any other information on results incl. tables

The 10-day windows began on day 7 after application, the mean value was calculated to be 25% biodegradation (ThOD_NO3). Therefore, the end of the 10-day window was day 17. After correction for the mean biochemical oxygen demand of the inoculum controls the mean biodegradation percentage based on ThOD_NO3at the end of the 10-day window was 78%; the criterion of the 10 day window was passed. The mean biodegradation percentage at the end of the 28-day exposure period was 84 %.

If no nitrification is considered, the mean biodegradation was 108% after 28 days of incubation. The criterion of the 10 day window was fulfilled on day 17, when the biodegradation was 100%.

The nitrate-N rate formed in the controls after 28 days of incubation was 1.803 mg/L (mean). The nitrate-N rate in the test item treated vessels was 8.923 mg/L (mean). Therefore, a nitrification occurred.In the case of a nitrification or transformation of ammonium to nitrate-N, the degradation of Oxaceprol was 83% (mean) after 28 days

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Interpretation of results:

readily biodegradable

Conclusions:

The degradation rate of Oxaceprol reached 60% within the 10-day window and after 28 days. Therefore, Oxaceprol is considered to be readily biodegradable.

Executive summary:

Aerobic activated sludge (microorganisms from a domestic waste­water treatment plant) was supplied by the sewage treatment plant of Bensheim, Germany.

The test item Oxaceprol was investigated for its ready biodegradability in a manometric respirometry test over a period of 28 days. The biodegradation was followed by the oxygen uptake of the microorganisms during exposure. As a reference item sodium benzoate was tested simultaneously under the same conditions as the test item, and functioned as a procedure control.

Degradation rate of test item calculated by the oxygen consumption of the aerobic activated sludge microorganisms after 28 days of incubation.

The degradation rate of Oxaceprol reached 60% within the 10-day window and after 28 days. Therefore, Oxaceprol is considered to be readily biodegradable.