Methyltriphenylphosphonium bromide

Biodegradation in water: screening tests

Administrative data

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2003-02-15 to 2003-06-24

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2003

Report date:

2003

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

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

Version / remarks:

adopted July 17, 1992

Deviations:

no

Test guideline 2

Qualifier:

according to guideline

Guideline:

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

Version / remarks:

December 1992

Deviations:

no

GLP compliance:

yes

Test material

Test material information

Constituent 1

Reference substance name:

Methyltriphenylphosphonium bromide

EC Number:

217-218-9

EC Name:

Methyltriphenylphosphonium bromide

Cas Number:

1779-49-3

Molecular formula:

C19H18P.Br

IUPAC Name:

methyl(triphenyl)phosphonium bromide

Test material form:

solid: particulate/powder

Study design

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic (adaptation not specified)

Details on inoculum:

- Source of inoculum/activated sludge (e.g. location, sampling depth, contamination history, procedure): municipal sewage treatment plant: 'Waterschap de Maaskant', ‘s-Hertogenbosch, the Netherlands.
- Storage length: Before use, the sludge was allowed to settle (30-90 minutes) and the liquid decanted for use as inoculum at the amount of 10 mL/L of mineral medium.
- Preparation of inoculum for exposure: The sludge was kept under continuous aeration until further treatment. Mineral components, Milli-RO water (ca. 80% total volume) and inoculum (1% final volume) were added to each bottle. This mixture was aerated with CO2-free air overnight to purge the system of CO2.
- Concentration of sludge: The concentration of suspended solids was 3.1 g/L in the concentrated sludge (information obtained from the municipal sewage treatment plant).

Duration of test (contact time):

29 d

Initial test substance concentration

Initial test substance concentration 1

Initial conc.:

19 mg/L

Based on:

test mat.

Initial test substance concentration 2

Initial conc.:

12 mg/L

Based on:

TOC

Parameter followed for biodegradation estimation

Parameter followed for biodegradation estimation:

CO2 evolution

Details on study design:

TEST CONDITIONS
- Composition of medium:
Stock solutions of mineral components
A) 8.50 g KH2PO4
21.75 g K2HPO4
67.20 g Na2HPO4 x 12 H2O
0.50 g NH4Cl dissolved in 1 L Milli-Q water, pH 7.4 2 ± 0.2
B) 22.50 g MgSO4 x 7H2O dissolved in 1 L Milli-Q water
C) 36.40 g CaCl2 x 2H2O dissolved in 1 L Milli-Q water.
D) 0.25 g FeCl3 x 6H2O dissolved in 1 L Milli-Q water.
Mineral medium
1 L mineral medium contains: 10 mL of solution (A), 1 mL of solutions (B) to (D) and Milli-RO water.
- Test temperature: 21.4 - 23.5 °C
- pH: at test start: 7.2, at test end: 7.5 - 8.0
- pH adjusted: no
- Suspended solids concentration: 3.1 g/L
- Continuous darkness: yes


SAMPLING
- Sampling frequency: Titrations were made every second or third day during the first 10 days, and thereafter at least every fifth day until the 28th day. Sampling: 0, 2, 5, 7, 9, 14, 19, 23, 27 and 29 days

CONTROL AND BLANK SYSTEM
- Inoculum blank: inoculum blank: containing only inoculum (2 bottles); Test vessels 2 litre all-glass brown coloured bottles.
- Toxicity control: containing test substance, reference substance and inoculum (1 bottle), Test vessels 2 litre all-glass brown coloured bottles.

STATISTICAL METHODS:
The first step in calculating the amount of CO2 produced is to correct for background (endogenous) CO2 production. Thus the amount of CO2 produced by a test material is determined by the difference (in ml of titrant) between the experimental and blank Ba(OH)2 traps.
The amount of 0.05 N HCI titrated is converted into mg of CO2 produced:

mg CO2 = [(0.05 x A ml HCI titrated)/ 2] x 44 = 1.1 x Δ mL of HCI titrated.
Relative degradation values were calculated from the cumulative CO2 production relative to the total expected CO2 production based on the total carbon content of the amount of test material present in the test bottles. They were plotted versus time together with the relative degradation of the positive control.

Reference substance

Reference substance:

acetic acid, sodium salt

Results and discussion

% Degradation

% Degradation 1

Parameter:

% degradation (CO2 evolution)

Value:

0

Sampling time:

0 d

Remarks on result:

other: mean of bottle A and B

% Degradation 2

Parameter:

% degradation (CO2 evolution)

Value:

0

Sampling time:

5 d

Remarks on result:

other: mean of bottle A and B

% Degradation 3

Parameter:

% degradation (CO2 evolution)

Value:

2

Sampling time:

14 d

Remarks on result:

other: mean of bottle A and B

% Degradation 4

Parameter:

% degradation (CO2 evolution)

Value:

4

Sampling time:

23 d

Remarks on result:

other: mean of bottle A and B

% Degradation 5

Parameter:

% degradation (CO2 evolution)

Value:

5

Sampling time:

29 d

Remarks on result:

other: mean of bottle A and B

Any other information on results incl. tables

The relative degradation values calculated from the measurements performed during the test period revealed 11 and 1% degradation of methyltriphenylphosphonium bromide for A and B respectively. Thus, the criterion for ready biodegradability (at least 60% biodegradation within the 10 -day window) was not met.

In the toxicity control more than 25% degradation occurred within 14 days (36%, based on ThCO2). Therefore, the test substance was assumed to be not inhibitory to microbial activity.

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Interpretation of results:

not readily biodegradable

Conclusions:

Methyltriphenylphosphonium bromide was not readily biodegradable under the conditions of the modified Sturm test presently performed.