Fatty acids, C16-18, 2-butyloctyl esters

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:

2005-01-13 - 2005-02-11

Reliability:

1 (reliable without restriction)

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2005

Report date:

2005

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

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

GLP compliance:

yes

Test material

Test material information

Constituent 1

Reference substance name:

Fatty acids, C16-18, 2-butyloctyl esters

EC Number:

309-831-6

EC Name:

Fatty acids, C16-18, 2-butyloctyl esters

Cas Number:

101227-08-1

Molecular formula:

C28H56O2 - C30H60O2

IUPAC Name:

Fatty acids, C16-18, 2-butyloctyl esters

Test material form:

other: liquid

Details on test material:

Name: ISOFOL ESTER 1202
Lot No. of test item: 02583 (indicated by the sponsor)
Hydrotox Nr.: 04/2201
CAS-No.: 101227-08-1 (indicated by the sponsor)
Certificate of analysis: available, from July 5th, 2004
Contents: fatty acid, C16, 18, 2-butyloctylester (indicated by the sponsor)
Appearance: yellow liquid
Storage-conditions: no special storage conditions required (indicated by the sponsor)
Durability: at least one year after delivery (indicated by the sponsor)
Solubility in water: insoluble (indicated by the sponsor)
TOC-content: 80.45% (measurement by Hydrotox)
Density: approx. 0.86 g/cm3 (20 ) (indicated by the sponsor)
Safety directions: hand protection should be adjusted to used chemicals (indicated by the sponsor)

Study design

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic, non-adapted

Details on inoculum:

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 of the region of Freiburg and has a capacity of 600.000 inhabitant equivalents. Sampling date of activated sludge was January 11th, 2005. Dry solids of the activated sludge was determined as 5.4 g/l by weight measurements after 2 h drying at 105°C (mean of triplicate measurements). The activated sludge was washed twice by settling the sludge, decanting the supernatant and re-suspending the sludge in aerated tap water.

Duration of test (contact time):

28 d

Initial test substance concentration

Initial conc.:

20 mg/L

Based on:

other: TOC

Parameter followed for biodegradation estimation

Parameter followed for biodegradation estimation:

CO2 evolution

Details on study design:

The CO2-free air production system consisted of an air compressor, two 1000 ml gas wash bottles filled with dry soda lime, followed by one bottle filled with 0.1 M NaOH (sodium hydroxide) and one gas wash bottle filled with demineralised water. The CO2-free air was passed on to an air distributewith two input and 22 output channels and through PE-tubes. Gas wash bottles (2000 ml volume) with lateral connecting pieces for butyl rubber septums were used as reactors. The liquid volume was fixed as 1.500 ml each. Mixing was performed by a magnetic stirrer with 2 cm stir bars. 43.4 µl of the test item were added into the three test vessels and the vessel for toxicity control, corresponding to a TOC concentration of 20 mg/l TOC. From the reference compound 5.15 ml of a stock solution of 10 g/l were added to the reference vessels and the vessels for toxicity control. The CO2 produced in the reactors was absorbed in two 250 ml gas wash bottles in series, each filled with 200 ml 0.2 M NaOH. Sampling was performed through the lateral connecting pieces through the butyl rubber septum using 5 ml PE syringes. The amount of CO2 released from the reactors is calculated through IC-measurements in the CO2-absorber while considering the amount of CO2 removed for IC-measurement.

Reference substance

Reference substance:

benzoic acid, sodium salt

Results and discussion

% Degradation

Parameter:

% degradation (CO2 evolution)

Value:

72.8

Sampling time:

28 d

Remarks on result:

other: at 20 mg TOC/L

Details on results:

The degradation extent of the test item was 72.8% within 28 days after acidification with HCl (mean value). On day 11 the mean degradation extent was already > 60% (63.1%, mean value table 1). Therefore the test item reached the pass level for ready biodegradability (60% ThCO2 and 10 d-window. The vessels run very parallel throughout the whole test. The degradation in the toxicity control was 75.8% within 14 days and 93.8% within 28 days (after acidification), so there was no inhibition of the inoculum caused by the test item. The highest mean CO2-evolution of the blank flasks was 28.4 mg/l within 28 days. The temperature range was 20.0 to 21.5 °C throughout the whole study. The aeration rate was in the tolerated range of 2.7 ¿ 5.5 bubbles/second (2.8 ¿ 5.1 bubbles/second).

BOD5 / COD results

Results with reference substance:

The reference compound sodium benzoate reached the pass levels for ready biodegradability within 7 days.

Any other information on results incl. tables

Table 1: Ultimate biodegradation after x days [% of ThCO2]
reactor	day	0	4	7	11	14	21	28	28 (after acidification)
7	Test flasks	0	22,8	43,9	58,3	60,6	70,7	73,2	70,7
8		0	31,4	61,7	67,1	73,3	75,0	76,0	73,2
9		0	30,2	49,0	63,8	64,6	72,8	75,4	74,5
13	reference flasks	0	62,1	81,9	88,0	92,3	91,7	92,7	89,6
14		0	57,6	82,7	88,3	92,2	95,2	95,8	93,3
15		0	62,5	83,1	88,8	92,4	93,7	96,4	97,0
	Toxicity control
21	Test item	0	42,0	61,5	72,9	75,8	85,2	93,9	93,8
	Reference item
Table 2: Mean CO2-evolution of blank flasks after x days
Day		0	4	7	11	14	21	28	28 (after acidification)
CO2-evolution [mg/l]		0	10,1	16,9	14,7	24,1	22,7	25,9	28,4

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Interpretation of results:

readily biodegradable

Conclusions:

The biodegradation of the test item was 72.8% within 28 days (after acidification).  The test item reached the criterion of ready biodegradation.

Executive summary:

The biodegradation of the test item was 72.8% within 28 days (after acidification).  The test item reached the criterion of ready biodegradation.