Reaction mass of sodium (methylbutyl and pentyl) sulfonate and sodium 1,2-bis(pentyloxycarbonyl)ethanesulphonate

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:

Date of study plan revision: June 28, 2019, Completion of study: September 30, 2020

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 301 F (Ready Biodegradability: Manometric Respirometry Test)

Version / remarks:

enhanced to 60 days

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Specific details on test material used for the study:

SOURCE OF TEST MATERIAL
- Source (i.e. manufacturer or supplier) and lot/batch number of test material:
Innospec, Batch ACRD0728
- Purity, including information on contaminants, isomers, etc.: Active matter content: 36.82% according to CoA

APPEARANCE
-Aqueous solution, colourless liquid

STABILITY AND STORAGE CONDITIONS OF TEST MATERIAL
- Storage condition of test material: Well closed container, at 8 - 30°C.
- Expiry date: December 31, 2019

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic, non-adapted

Details on inoculum:

Fresh samples of activated sludge are withdrawn on October 01st, 2019 from the sewage treatment plant Ruhrverband Kläranlage, Sunthelle 6, 57392 Schmallenberg, Germany, which is mainly fed with municipal wastewater.
The samples were 2mm sieved after the arrival at the laboratory, washed once with mineral medium and kept under aerobic conditions until use. The sludge was left to settle for ca. one hour prior to use. Subsequently the supernatant was discarded and the concentration of suspended solids was measured in the remaining sludge. The concentration was adjusted to 4.4 g/L and verified by dry mass measurement. The concentration used in the test was 29.6 mg dry mass/L (7.40 mg dry mass/250 mL).

Duration of test (contact time):

60 d

Initial conc.:

53.2 mg/L

Based on:

ThOD

Initial conc.:

88 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

A measured volume of inoculated mineral medium, containing a known concentration of test item (giving 50 - 100 mg ThOD/L) as the nominal sole source of organic carbon, is stirred in a closed flask at a constant temperature of 22 °C ± 1°C for up to 28 days. In this study, the test item concentration is 88 mg test item/L equivalent to 53.2 mg ThOD/L. The consumption of oxygen is determined by measuring the quantity of oxygen (produced electrolytically) required to maintain constant gas volume in the respirometer flask. Evolved carbon dioxide is absorbed in a suitable absorbent. The amount of oxygen taken up by the microbial population during biodegradation of the test item (corrected for uptake by blank inoculum, run in parallel) is expressed as a percentage of ThOD.

Reference substance:

benzoic acid, sodium salt

Test performance:

The solution of the reference substance in the mineral medium equivalent to a concentration of 100 mg/L was prepared using a stock solution (10 g/L). The solution of the test item in the mineral medium equivalent to a concentration of 88 mg/L was prepared by adding the required amount to ensure a final concentration of 88 mg/L (22 mg/250 mL) directly on a weight basis via Teflon discs to the test vessels. Subsequently, the mineral medium was added to the vessels. Further flasks with mineral medium only were prepared for inoculum controls. A further solution containing both test and reference item at the same concentrations as in the individual solutions (88 mg/L and 100 mg/L, respectively) was prepared to determine the possible toxicity of the test item.
Before test start the pH values of all solutions are determined and adjusted to 7.4 ± 0.2 with H2SO4 (50 g/L). The vessels were allowed to reach the desired temperature and were inoculated with prepared activated sludge to give a concentration of suspended solids not greater than 30 mg/L (in fact 29.6 mg/L). The total volume of solution was 250 mL in 500 mL respirometer flasks. The solutions were stirred during the whole test duration. In this way, dispersion of the test item and the contact between inoculum and test item was maximized. Twice a week the correct incubation temperature of the water bath and an adequate stirring were checked. At the end of the test the pH values of all solutions were determined.
The test was run for a period of 28 days, in darkness at 22°C ± 1°C in a water bath. The consumed oxygen is replaced by electrolytically generated oxygen.

Key result

Parameter:

% degradation (O2 consumption)

Value:

95

St. dev.:

15

Sampling time:

28 d

Results with reference substance:

The percentage degradation of the reference item was average 88% and hence exceeded the pass level of 60% by day 14

No inhibitory effects of the test item were observed: more than 25% biodegradation (62.9% biodegradation based on ThOD) was determined within 14 days (as specified in the validity criteria in paragraph 25 of the OECD 301 guidelines).

Validity criteria fulfilled:

yes

Remarks:

(1) Degradation of reference: 88% (2) Difference of extremes of replicate values at the end of the individual 10-day windows: 3% (3) oxygen uptake of the inoculum blank < 60 mg/L on day 28 (4) pH value inside the range of 6.0 - 8.5

Interpretation of results:

readily biodegradable

Conclusions:

In conclusion, Reaction mass of sodium (methylbutyl and pentyl) sulfonate and sodium 1,2-bis(pentyloxycarbonyl)ethanesulphonate is readily biodegradable.

Executive summary:

A study was performed at the Fraunhofer Institute for Molecular Biology and Applied Ecology (IME) to investigate the biodegradation of Reaction mass of sodium (methylbutyl and pentyl) sulfonate and sodium 1,2-bis(pentyloxycarbonyl)ethanesulphonate over a 28-day period in a Manometric Respirometry Test according to OECD guideline 301 F (1992) [5] and EC method C.4-D (440/2008/EEC) [6]. The test medium was inoculated with microorganisms from a digester of a sewage treatment plant mainly fed with municipal wastewater.

The test solutions were stirred in closed flasks at 22 °C ± 1°C for 28 days. The rate of degradation was monitored by measuring the quantity of oxygen required to maintain a constant gas volume in the respirometer flasks over a 28-d period. The amount of oxygen taken up by the microbial population during biodegradation of the test item at a concentration of 88 mg/L (ThOD = 53.2 mg/L), corrected for uptake by the blank inoculum run in parallel, was expressed as a percentage of the ThOD (theoretical oxygen demand). In order to check the procedure, sodium benzoate was used as a readily degradable reference item at a concentration of 100 mg/L, along with a toxicity control at 88 mg/L test item and 100 mg/L reference item.

The test fulfills the validity criteria of the guideline: (1) The percentage degradation of the reference item was average 87.9% and hence exceeded the pass level of 60% by day 14, (2) with 3%, the difference of extremes of replicate values at the end of the individual 10-day windows, was less than 20%, (3) the oxygen uptake of the inoculum blank is < 60 mg/L after 28 days and the pH value was inside the range of 6.0 - 8.5.

No inhibitory effects of the test item were observed: 76%. i.e., more than 25% degradation was determined on day 14 in the toxicity control.

The biodegradation of Reaction mass of sodium (methylbutyl and pentyl) sulfonate and sodium 1,2-bis(pentyloxycarbonyl)ethanesulphonate was average 95% at a concentration of 88 mg/L (53.2 mg ThOD/L) after 28 days. Biodegradation within the 10-day-window – which started between day 1 and 2 – was found to be average 74% and hence exceeded the pass level of 60%. The 10-day window is not applicable to a UVCB substance.

Description of key information

A key study for ready biodegradability is available. The test was performed according to OECD 301 F and is valid according to the guideline criteria. After incubation for 28 days, 95 ± 15% (85-105) of the test material was ultimately degraded. The 10-day window is not applicable, since the substance is a UVCB (homologue distribution).

Key value for chemical safety assessment

Biodegradation in water:

readily biodegradable