Xanthylium, 9-(2-carboxyphenyl)-3,6-bis(diethylamino)-, hydrogen bis[3-[(4,5-dihydro-3-methyl-5-oxo-1-phenyl-1H-pyrazol-4-yl)azo]-2-hydroxy-5-nitrobenzenesulfonato(3-)]chromate(3-), compd. with 3-[(2-ethylhexyl)oxy]-1-propanamine

Biodegradation in water: screening tests

Description of key information

The ready biodegradability of the test substance was examined in a test (BASF SE, 2017) according to the OECD 301 B (CO2 evolution, modified Sturm test). After 28 days the test substance was biodegraded by an average of < 10 % CO2/ThCO2. Therefore, the required pass level for ready biodegradability within a ten day window was not reached and the test substance was found to be not readily-biodegradable under the test conditions.

Key value for chemical safety assessment

Biodegradation in water:

under test conditions no biodegradation observed

Additional information

The ready biodegradability of the test substance was examined in a test (BASF SE, 2017) according to the OECD 301 B (CO2 evolution, modified Sturm test, 1992). The biodegradation of the test substance was followed by exposing it to the active sludge of a domestic waste water treatment plant from Mannheim (Germany). The substance was poorly soluble in water. The incubation bottles were stirred on magnetic stirrers; the aeration was performed with carbon dioxide free air at a flow of approximately 800 mL per hour. The TIC- and DOC-analyses were performed as repeat determination. The bottles were connected to two serial scrubbing bottles (total volume 250 mL) filled with 100 mL 0.05 mol sodium hydroxide solution for the adsorption of carbon dioxide from biodegradation processes. Usually twice a week the Total Inorganic Carbon (TIC) values of the adsorption solutions of the first trap were determined and used for the calculation of the produced carbon dioxide. After each sampling the second trap was moved forward and the new trap with fresh sodium hydroxide solution was placed into the second position. Each trap was analyzed separately. The TIC-value of the freshly prepared sodium hydroxide solution was determined and considered by the calculation of biogenic produced carbon dioxide amount. The inoculum was aerated for about 48 hours at 22 +/- 2 °C. The active sludge concentration was 30 mg/L /dry weight). Since the test substance was insufficiently soluble in water, no DOC-measurements could be performed from the test assay of the inhibition control and from the test substance test assays. The initial concentrations of the test substance were 24.9, 35,9 and 36.0 mg/L (corresponding to 20 mg/L TOC). As a reference compound (procedure control), aniline was tested simultaneously under the same conditions. The degree of biodegradation in the inhibition control after 14 days was determined to be 32 % CO2/ThCO2, therefore no inhibitory effect on the microorganisms was observed. In the procedure controls, the reference compound aniline was readily biodegraded by an average of 81 % after 14 days. The validity criteria were met. After 28 days the test substance was biodegraded by an average of < 10 % CO2/ThCO2. Therefore, the required pass level for ready biodegradability within a ten day window was not reached and the test substance was found to be not readily-biodegradable under the test conditions.