3,3'-[azoxybis[(2-methoxy-p-phenylene)azo]]bis[4,5-dihydroxynaphthalene-2,7-disulphonic] acid, lithium sodium salt

Biodegradation in water: screening tests

Link to relevant study record(s)

Reference

Endpoint:

biodegradation in water: screening test, other

Type of information:

experimental study

Adequacy of study:

key study

Study period:

January 2003

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

comparable to guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 301 A (Ready Biodegradability: DOC Die Away Test)

GLP compliance:

no

Inoculum or test system:

sewage, domestic (adaptation not specified)

Remarks:

100 mL of secondary effluent of a urban sewage treatment plant / L

Duration of test (contact time):

28 d

Details on study design:

TEST CONDITIONS:
- Duration of the test: 28 days
- Test temperature: 22 ± 2 ºC
- Fotoperiod: difuse light
- Type of flasks: conic flask of 2,5 L / volume used 1,5L
- Number of culture flasks/concentration: 2
- Initial concentration of the study: 10 mg/L of TOC
- Final concentration of the study: 30 mg/L of TOC
- Reference substance: sodium acetate
- Inoculum: 100 mL of secondary effluent of a urban sewage treatment plant / L
- Composition of medium:
Solution 1:
KH2PO4 8,5 g/L H2O
K2HPO4 21,75 g/L H2O
Na2HPO4 2H2O 33,4 g/L H2O
NH4Cl 0,5 g/L H2O
Solution 2: CaCl2 2H2O 36,4 g/L H2O
Solution 3: MgSO4 7H2O 22,5 g/L H2O
Solution 4: FeCl3 6H2O 0,25 g/L H2O

Add to 1000 mL of deionized water: solution 1: 10 mL; solución 2: 1 mL; solución 3:1 mL; solución 4:1 mL

DEVELOPMENT OF THE STUDY:
- 800 ml of mineral medium are introduced into 2.5-liter conical flasks and sufficient volumes of the mother liquors of the test substance and of reference are added to the individual flasks to obtain a substance concentration equivalent to 10-30 mg toc / L.
Taking into account that 1 g / L of THE product (0.75 g / L of active material) has a TOC value of 314.2 mg / L, a solution of the product of 31.8 mg / L (23, 85 mg / L of active material) is prepared to obtain a TOC value of 10 mg / L, and a product solution of 95.5 mg / L (71.63 mg / L of active material) to obtain a TOC value of 30 mg / L.

- The pH is adjusted to 7.4.

- The flasks are inoculated with effluent of wastewater in the proportion of 100 ml / L.
- An inoculum control is prepared with the mineral medium, but without substance or reference substance.
- All flasks are flushed at 1.5 L with mineral medium and, after shaking, a sample is taken from each flask to determine the initial concentration of total dissolved organic carbon (TOC).
- The flasks are covered with aluminum foil, so as to allow free circulation of air between the flask and the surrounding atmosphere.
- Next, the flasks are placed in the agitator to start the test.
- Throughout the study, the concentrations of TOC in each flask are determined in duplicate at time intervals of 2-3 days. For each determination, only the minimum necessary volume of problem suspension is taken.
- Before taking the samples, it is necessary to compensate the losses that have been produced by evaporation of the test medium in the flasks, adding the necessary amount of dilution water. Before taking samples, the culture medium is well shaken and is made sure that the material that has adhered to the walls of the containers dissolves or resuspens.
- The samples are filtered by membrane immediately after taking them. Each filtered sample is analyzed using a TOC analyzer.

Reference substance:

acetic acid, sodium salt

Key result

Parameter:

% degradation (DOC removal)

Value:

3

Sampling time:

28 d

% of biodegradation of Direct Blue 281 along the time

	% biodegradation
		Direct Blue 281
time	sodium acetate	10 ppm TOC	30 ppm TOC
0h	0	0	0
day 1	52.7	0	0
day 2	86.3	1	0
day 5	97,4	2	1
day 7	100	3	2
day 9	100	3	2
day 12	100	3	2
day 14	100	3	2
day 16	100	3	2
day 19	100	3	2
day 21	100	3	2
day 23	100	3	2
day 26	100	3	2
day 28	100	3	2

Validity criteria fulfilled:

yes

Interpretation of results:

not readily biodegradable

Conclusions:

The test item Direct Blue 281 (batch: PF-11895) shows no biodegradation after 28 days of testing.

Executive summary:

The determination of the biodegradability of Direct Blue dye 281 (batch: PF-11895) was carried out following the OECD Guideline 301A (1992) and the Spanish Royal Decree 363/1995 (BOE No. 133 of June 1995).

Biodegradation is defined as the decomposition of an organic compound by the biological action of microorganisms, which results in the disappearance of the original molecular structure and the formation of smaller organic molecules.

The starting point is a known concentration of the test substance (10-40 mg TOC / L) and the follow-up is performed by analysis of Total Dissolved Organic Carbon (TOC) at time intervals over a period of 28 days.

The results are expressed as a percentage of biodegradation after 28 days.

The result obtained in this test indicates that the Direct Blue 281 dye does not show biodegradation after 28 days of testing.

Description of key information

One test according to OECD Guideline 301A conducted on the substance shows that it is not readily biodegradable.

Key value for chemical safety assessment

Biodegradation in water:

under test conditions no biodegradation observed

Type of water:

freshwater