Trimethyl citrate

Biodegradation in water: screening tests

Administrative data

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2018

Report date:

2018

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

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

GLP compliance:

yes

Test material

Test material information

Constituent 1

Reference substance name:

Trimethyl citrate

EC Number:

216-449-2

EC Name:

Trimethyl citrate

Cas Number:

1587-20-8

Molecular formula:

C9H14O7

IUPAC Name:

1,2,3-trimethyl 2-hydroxypropane-1,2,3-tricarboxylate

Study design

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic (adaptation not specified)

Details on inoculum:

6.3.1 Specification
Activated sludge from a biologic sewage treatment plant was used as inoculum. The cho-sen plant treats mostly domestic sewage.
6.3.2 Source and Pre-Treatment of inoculum
6.3.2.1 Source
The sludge was taken from the activation basin of the sewage treatment plant in D-67480 Edenkoben.
Date of collection: 23. Feb. 2018, batch no: 20180223.
6.3.2.2 Pre-Treatment
The sludge was filtrated, washed with test medium (2x) and re-suspended in test medium. It was then aerated until use. The dry matter was determined to contain 3980 mg of sus-pended solids/L.

Duration of test (contact time):

ca. 28 d

Initial test substance concentration

Initial conc.:

ca. 20 mg/L

Based on:

other: organic carbon

Parameter followed for biodegradation estimation

Parameter followed for biodegradation estimation:

CO2 evolution

Details on study design:

This study was performed in order to evaluate aerobic elimination and degradation poten-tial of Trimethyl citrate in a test for ready biodegradability, using a test item concentration of nominally 20 mg organic carbon/L (corresponding to 43.3 mg Trimethyl citrate/L).
The test item in a mineral medium was inoculated and incubated under aerobic conditions in the dark. The amount of DOC in the test solution due to the inoculum was kept as low as possible compared with the amount of organic carbon due to the test item. Allowance was made for the endogenous activity of the inoculum by running parallel blanks with inoculum but without test item. A positive control was run in parallel to check the operation of the procedures. Degradation was followed by determining the carbon dioxide produced. Measurements were taken at sufficiently frequent intervals to allow the identification of the beginning and end of biodegradation.
The test lasted for 28 days.

Reference substance

Reference substance:

aniline

Results and discussion

Test performance:

All validity criteria were met.
Degradation behaviour of positive control and toxicity control was normal. Abiotic degradation reached 0.4 %. Both replicates of the test item showed very good correspondence.

% Degradation

% Degradation 1

Key result

Parameter:

% degradation (CO2 evolution)

Value:

ca. 49

Sampling time:

4 d

% Degradation 2

Key result

Parameter:

% degradation (CO2 evolution)

Value:

ca. 94

Sampling time:

28 d

Details on results:

The test item Trimethyl citrate is considered as “not readily biodegradable“.
The degree of biodegradation reached 94 % after 28 days.
The 10-day-window began on day 4 (graphic evaluation), at its end, 49 % degrada-tion were reached, missing the pass level of 60 % given in the OECD guideline.
Degradation surpassed 60 % within 28 days. Therefore, the test item is considered as “ultimately biodegradable”, within 28 days.
Abiotic degradation reached 0.4 %.

BOD5 / COD results

BOD5 / COD

Key result

Remarks on result:

not measured/tested

Results with reference substance:

Degradation of the positive control was 67 % after 11 days.

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Interpretation of results:

not readily biodegradable

Conclusions:

The test item Trimethyl citrate is considered as “not readily biodegradable“. Therefore, when applying the 10-day-window, the test item Trimethyl citrate is not readily biodegradable following OECD 301B and EU C.4-C respectively. As degradation sur-passed 60% in the course of the test, Trimethyl citrate is considered as ultimately biode-gradable.