Boron, (acetonitrile)trifluoro-, (T-4)-

Biodegradation in water: screening tests

Administrative data

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

migrated information: read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Study period:

2009

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: The study was conducted in compliance with GLP regulation and guideline.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2010

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 310 (Ready Biodegradability - CO2 in Sealed Vessels (Headspace Test)

GLP compliance:

yes (incl. QA statement)

Test material

Test material information

Constituent 1

Reference substance name:

Acetonitrile

EC Number:

200-835-2

EC Name:

Acetonitrile

Cas Number:

75-05-8

Molecular formula:

C2H3N

IUPAC Name:

acetonitrile

Details on test material:

- Name of test material (as cited in study report): acetonitrile

Study design

Oxygen conditions:

other: Sealed vessels

Inoculum or test system:

activated sludge, non-adapted

Details on inoculum:

- Source of inoculum/activated sludge (e.g. location, sampling depth, contamination history, procedure): Totnes Sewage Treatment Works, Devon, UK. This works treats sewage of predominantly domestic origin. At the laboratory, the activated sludge was kept aerated at room temperature and the pH maintained at 7.0 ± 1.0 until initiation of the test on the same day.

- On the exposure start day, the activated sludge was centrifuged, washed and resuspended in the test medium and the solids concentration determined. This sludge was then diluted in medium to a final sludge solids concentration of 4 mg/L, and added to the test bottles.

Duration of test (contact time):

21 d

Initial test substance concentration

Initial conc.:

684 mg/L

Based on:

other: equivalent to nominal 400 mg/L as carbon

Parameter followed for biodegradation estimation

Parameter followed for biodegradation estimation:

CO2 evolution

Details on study design:

TEST CONDITIONS
- Composition of medium: 85 mg of KH2PO4, 217.5 mg of K2HPO4, 334 mg of Na2HPO4*2H2O, 5 mg of NH4Cl, 22.5 mg of MgSO4*7H2O, 36.4 mg of CaCl2*2H2O, 0.25 mg of FeCl3*6H2O.
- Test temperature: 22 ± 2°C.
- pH: pH of the test medium prior to use was measured and adjusted as necessary to 7.4 ± 0.2.
- Other: Sufficient replicates were prepared for five replicates to be analysed for inorganic carbon at the end of the study, together with one replicate for pH analysis, and triplicate analysis on each other sample occasion.

TEST SYSTEM
- Culturing apparatus: nominal 125 mL serum bottles, sealed with butyl rubber septa and aluminium crimp caps.

CONTROL AND BLANK SYSTEM
- Inoculum blank: Inoculum blanks contained no test or reference substance in order to demonstrate there was no other carbon source in the medium.
- Toxicity control: Toxicity controls contained the test and reference substances, both at nominal 20 mg/L as carbon, and were used if the test substance failed to degrade during the test period, to show if the failure had been due to inhibition of the inoculum by the test substance.
- Other: Positive controls contained sodium benzoate at nominal 20 mg/L, as carbon, to demonstrate the viability of the inoculum.

TOC DETERMINATION
- The TOC of the acetonitrile and sodium benzoate stock solutions was determined using tube kits provided by Hach Lange Ltd using a DR2800 spectrophotometer for evaluation. In a two stage process, inorganic carbon is expelled from the sample, then the remaining organic carbon is oxidised to carbon dioxide. The carbon dioxide passes through a membrane into an indicator cuvette, where a colour change occurs, which is evaluated spectrophotometrically.

IC DETERMINATION
- Samples from the test vessels were analysed for IC using a Hach Lange IL500 carbon analyser. In principle, the sample was mixed with phosphoric acid, which released the IC as carbon dioxide. This was then purged from the liquid by a stream of nitrogen, which carried the released carbon dioxide to an infra red (NDIR) detector, which quantified the IC in the sample.

Reference substance

Reference substance:

benzoic acid, sodium salt

Results and discussion

% Degradation

Parameter:

% degradation (CO2 evolution)

Value:

70

Sampling time:

21 d

Remarks on result:

other: 62% degradation in the 10 day window from day 4 to day 14

Details on results:

The measured TOC of the acetonitrile stock solution was 313 mg C/L, lower than the nominal concentration of 400 mg C/L. It was considered possible that the low result was due to loss of acetonitrile by evaporation from the test solution, either before the analysis was done, or during removal of inorganic carbon. Therefore, a fresh acetonitrile stock solution was prepared and analysed with and without the inorganic carbon removal step. The organic carbon measured in this stock was 291 and 337 mg C/L, with and without IC removal, respectively. This indicates that the low result was probably not due to loss of acetonitrile by evaporation. It was decided to calculate the biodegradation results based on both nominal and measured TOC results, for completeness. More than 60% degradation was achieved within the 10 day window as expected for a biodegradable substance, thus confirming that the activated sludge contained viable organisms.

BOD5 / COD results

Results with reference substance:

The measured TOC of the sodium benzoate stock solution was 400 mg C/L, equal to the nominal concentration of 400 mg C/L. On day 28 sodium benzoate (the reference substance) attained a mean level of biodegradation (based on the IC:TOC ratio) of 91%.

Any other information on results incl. tables

Day	Percentage Biodegradation
	Acetonitrile (20 mg C/L)	Reference substance (20 mg C/L)
4	11	69
7	52	81
14	62	81
21	70	91

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Remarks:

Reference substance results were within the expected range.

Interpretation of results:

readily biodegradable