Potassium 3,5,5-trimethylhexanoate

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:

2016

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

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

Deviations:

no

Qualifier:

equivalent or similar to guideline

Guideline:

EU Method C.4-C (Determination of the "Ready" Biodegradability - Carbon Dioxide Evolution Test)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Specific details on test material used for the study:

Name: Potassium 3,5,5-trimethylhexanoate
CAS No.: 93918-10-6
Batch No.: PURS151015
Purity: 99.4%
Physical State: solid
Colour: white
Molecular Weight: 196.33 g/mol
Storage Conditions: room temperature
Re-certification Date: 14 October 2016

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic, non-adapted

Details on inoculum:

Activated sludge, municipal wastewater treatment
Breisgauer Bucht, 30 mg dry solids per litre

Duration of test (contact time):

28 d

Initial conc.:

20 mg/L

Based on:

TOC

Parameter followed for biodegradation estimation:

CO2 evolution

Details on study design:

The CO2-evolution test determines the ready biodegradability of test items according to the Modified Sturm Test. A solution or suspension of the test item in a mineral medium, corresponding to 10 - 20 mg TOC/L, is inoculated with activated sludge (30 mg d. s./L). The test vessels are aerated by the passage of carbon dioxide-free air and are incubated under aerobic conditions in diffuse light for 28 days. Degradation is followed by determining the carbon dioxide produced and absorbed to sodium hydroxide via IC-measurement (IC = inorganic carbon). The amount of carbon dioxide produced from the test item less the amount derived from the blank inoculum is expressed as a percentage of ThCO2 (theoretical amount of CO2). The pass level for ready biodegradability is 60% of ThCO2 and must be reached within a 10-d window. Activated sludge from the municipal wastewater treatment plant Breisgauer Bucht was used as inoculum with a concentration corresponding to 30 mg dry solids per litre. The treatment plant clarifies predominantly domestic wastewater and has a capacity of 600.000 inhabitant equivalents. Sampling date of activated sludge was on 15 March 2016. Dry solid of the activated sludge was determined as 5.5 g/L by weight measurements after drying at 105°C (mean of triplicate measurements). The activated sludge was washed twice with tap water by settling the sludge, decanting the supernatant and re-suspending the sludge.

Reference substance:

benzoic acid, sodium salt

Key result

Parameter:

% degradation (CO2 evolution)

Value:

87.9

Sampling time:

28 d

Validity criteria fulfilled:

yes

Interpretation of results:

readily biodegradable

Conclusions:

The test item is readily biodegradable. The  degradation  of  the  test  item  at  the  end  of  the  test  was  87.9%  (28  d  after acidification, mean of three replicates).

Executive summary:

The  degradation  of  the  test  item  at  the  end  of  the  test  was  87.9%  (28  d  after acidification, mean of three replicates). The test item reached the criteria for ready biodegradability (60% ThCO2 within a 10-d window).  The degradation of the toxicity control after 14 days was 86.1%. The test item had no inhibitory effects to the inoculum according to the criterion of the guideline.

Description of key information

The  degradation  of  the  test  item  at  the  end  of  the  test  was  87.9%  (28  d  after acidification, mean of three replicates). The test item reached the criteria for ready biodegradability (60% ThCO2 within a 10-d window).  The degradation of the toxicity control after 14 days was 86.1%. The test item had no inhibitory effects to the inoculum according to the criterion of the guideline.

Key value for chemical safety assessment

Biodegradation in water:

readily biodegradable