1-(bis(2-(1,3-dimethylbutylideneamino)ethyl)amino)-3-phenoxypropan-2-ol

Biodegradation in water: screening tests

Administrative data

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2018

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

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

Deviations:

no

Test guideline 2

Qualifier:

according to guideline

Guideline:

other: ISO 10634

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Test material

Test material information

Constituent 1

Reference substance name:

1-(bis(2-(1,3-dimethylbutylideneamino)ethyl)amino)-3-phenoxypropan-2-ol

EC Number:

271-340-7

EC Name:

1-(bis(2-(1,3-dimethylbutylideneamino)ethyl)amino)-3-phenoxypropan-2-ol

Cas Number:

68541-07-1

Molecular formula:

C25H43N3O2

IUPAC Name:

1-(bis(2-(1,3-dimethylbutylideneamino)ethyl)amino)-3-phenoxypropan-2-ol

Test material form:

liquid

Specific details on test material used for the study:

Appearance: Light yellow liquid
Batch: UL18401660
Purity/Composition: ca. 91.48% (
Test item storage: At room temperature
Stable under storage conditions until: 15 April 2020 (expiry date)

Study design

Oxygen conditions:

aerobic

Inoculum or test system:

sewage, predominantly domestic (adaptation not specified)

Details on inoculum:

Source The source of test organisms was activated sludge freshly obtained from a municipal sewage treatment plant: 'Waterschap Aa en Maas', 's-Hertogenbosch, The Netherlands, receiving predominantly domestic sewage.
Treatment The freshly obtained sludge was kept under continuous aeration until further treatment. Before use, the sludge was coarsely sieved (1 mm) and washed with mineral medium. After treatment the concentration of suspended solids (SS) was determined to be 3 g/L in the concentrated sludge as used for the test. The magnetically stirred sludge was used as inoculum at the amount of 3 mL per litre of mineral medium, leading to a SS concentration of 8 mg/L.
Reason for selection The test has been accepted internationally for determining the 'ready' biodegradability of test items under aerobic conditions.

Details on study design:

Test duration 28 days for the inoculum blank and test item (last CO2 measurement on day 29).
14 days for the procedure and toxicity control (last CO2 measurement on day 15).
During the test period, the test media were aerated and stirred continuously.
Test vessels 2 litre brown coloured glass bottles.
Milli- RO water Tap-water purified by reverse osmosis (Milli- RO) and subsequently passed over activated carbon.
Stock solutions of A) 8.50 g KH2PO4
mineral components 21.75 g K2HPO4
67.20 g Na2HPO4.12H2O
0.50 g NH4Cl
dissolved in Milli- RO water and made up to 1 litre, pH 7.4 ± 0.2
B) 22.50 g MgSO4.7H2O dissolved in Milli- RO water and
made up to 1 litre.
C) 36.40 g CaCl2.2H2O dissolved in Milli- RO water and
made up to 1 litre.
D) 0.25 g FeCl3.6H2O dissolved in Milli- RO water and
made up to 1 litre.

Mineral medium 1 litre mineral medium contains: 10 mL of solution (A),
1 mL of solutions (B) to (D) and Milli- RO water.
Barium hydroxide 0.0125 M Ba(OH)2 (Boom, Meppel, The Netherlands), stored in a sealed vessel to prevent absorption of CO2 from the air.

Synthetic air (CO2 < 1 ppm) A mixture of oxygen (ca. 20%) and nitrogen (ca. 80%) was passed through a bottle, containing 0.5 - 1 litre 0.0125 M Ba(OH)2 solution to trap CO2 which might be present in small amounts. The synthetic air was passed through the scrubbing solutions at a rate of approximately 1-2 bubbles per second (ca. 30-100 mL/min).

Illumination The test media were excluded from light.

Preparation of Bottles
Pre-incubation medium The day before the start of the test (day -1) mineral components, Milli- RO water (ca. 80% of final volume) and inoculum were added to each bottle. This mixture was aerated with synthetic air overnight to purge the system of CO2.
Type and number of bottles Test suspension: containing test item and inoculum (2 bottles).
Inoculum blank: containing only inoculum (2 bottles)
Procedure control: containing reference item and inoculum (1 bottle).
Toxicity control: containing test item, reference item and inoculum (1 bottle).
Preparation At the start of the test (day 0), test and reference item were added to the bottles containing the microbial organisms and mineral components.
The volumes of suspensions were made up to 2 litres with Milli- RO water, resulting in the mineral medium described before.
Three CO2-absorbers (bottles filled with 100 mL 0.0125 M Ba(OH)2) were connected in series to the exit air line of each test bottle.

Reference substance

Reference substance:

acetic acid, sodium salt

Results and discussion

Preliminary study:

The ThCO2 of the test item was calculated to be 2.36 mg CO2/mg.
The ThCO2 of sodium acetate was calculated to be 1.07 mg CO2/mg.

Test performance:

All results presented in the tables of the report are calculated using values as per the raw data rounding procedure and may not be exactly reproduced from the individual data presented. All data are presented in Appendix 1. The results of CO2 production and biodegradation in blank bottles, background bottles and each test bottle are listed Table 2 to 8. Table 9 contains the comparison of biodegradation of test item in bottles A and B.

% Degradation

% Degradation 1

Parameter:

% degradation (CO2 evolution)

Value:

ca. 53

Sampling time:

28 d

% Degradation 2

Parameter:

% degradation (CO2 evolution)

Value:

ca. 39

Sampling time:

28 d

Details on results:

2. The difference of duplicate values for %-degradation of the test item was always less than 20% (actual result: ≤ 14%).
3. The total CO2 release in the blank at the end of the test did not exceed 40 mg/L (56.0 mg CO2 per 2 litres of medium, corresponding to 28.0 mg CO2/L).
4. The Inorganic Carbon content (IC) of the test item (suspension) in the mineral medium at the beginning of the test was less than 5% of the Total Carbon content (TC). Since the test medium was prepared in tap-water purified by reverse osmosis (Milli- RO water (Millipore Corp., Bedford, Mass., USA, carbon levels < 500 ppb)), IC was less than 5% of TC (mainly coming from the test item, 11 mg TOC/L).
The relative biodegradation values calculated from the measurements performed during the test period revealed 53% and 39% biodegradation of test item (based on ThCO2), for the duplicate vessels tested. Thus, the criterion for ready biodegradability (at least 60% biodegradation within a 10-day window) was not met.
In the toxicity control, more than 25% biodegradation occurred within 14 days (60%, based on ThCO2). Therefore, the test item was assumed not to inhibit microbial activity.
Functioning of the test system was checked by testing the reference item sodium acetate, which showed a normal biodegradation curve (actual result: 74% biodegradation in 14 days)

BOD5 / COD results

Results with reference substance:

74% biodegradation in 14 days

Any other information on results incl. tables

The temperature recorded in a vessel with water in the same room varied between 22 and 23°C. The pH values of the different test media are presented inTable1.

Table1          
pH Values of Different Test Media

Test medium:	At the start of the test:	On day 14:	On day 28:
Blank control (A)	7.7 → 7.6^1	-	7.6
Blank control (B)	7.7^2	-	7.6
Procedure control	7.6	7.8	-
Test item (A)	7.7 → 7.6^1	-	7.7
Test item (B)	7.7 → 7.6^1	-	7.7
Toxicity control	7.7 → 7.6^1	7.8	-

¹: Adjusted using 1 M HCl (Merck, Darmstadt, Germany)

²: Value was recorded as 7.7 but not adjusted; see also deviation inAppendix 2.

 

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Interpretation of results:

inherently biodegradable

Conclusions:

In conclusion, 1-(bis(2-(1,3-dimethylbutylideneamino) ethyl)amino)-3-phenoxypropan-2-ol was not readily biodegradable under the conditions of the modified Sturm test presently performed. However, since results of the present test indicate that the pass level criterion was almost fulfilled for bottle A, results can be used to indicate inherent biodegradability.

Executive summary:

The objective of the studywas to evaluate the biodegradability in aerobic aqueous medium, with microbial activity introduced by inoculation with activated sludge, of the test item 1-(bis(2-(1,3-dimethylbutylideneamino) ethyl)amino)-3-phenoxypropan-2-ol.

The study procedures described in this report were in compliance with the OECD guideline No. 301 B, 1992. In addition, the procedures were designed to meet the test methods of the ISO standard 10634, 1995.

The test item was a light yellow liquid with a purity of 91.48%. Because of the low purity (<95%),Total Organic Carbon (TOC) content of the test item was confirmed by TOC analysis. The TOC content was 64.38%. Based on TOC content ThCO₂of the test item was calculated to be 2.36 mg CO₂/mg. The test item was tested in duplicate at a target concentration of 16.5 mg/L, corresponding to 11 mg TOC/L.

The study consisted of six bottles:

·        2 inoculum blanks (no test item),

·        2 test bottles (test item),

·        1 procedure control (sodium acetate) and

·        1 toxicity control (test item plus sodium acetate).

Since the test item was not sufficiently soluble to allow preparation of an aqueous solution at a concentration of 1 g/L, weighed amounts were added to the 2 litre test bottles containing medium with microbial organisms and mineral components. To this end, small watch glasses were used to transfer the weighed amounts of test item to the respective test bottles. The test solutions were continuously stirred during the test to ensure optimal contact between the test item and test organisms. Test duration was28 days for inoculum blank and test item (last CO₂measurement on day 29) and 14 days for procedure and toxicity control (last CO₂measurement on day 15).

The relative biodegradation values calculated from the measurements performed during the test period revealed 53% and 39% biodegradation of test item (based on ThCO₂), for the duplicate vessels tested. Thus, the criterion for ready biodegradability (at least 60% biodegradation within a 10-day window) was not met.

In the toxicity control, the test item was found not to inhibit microbial activity.

Since all criteria for acceptability of the test were met, this study was considered to be valid.

In conclusion,1-(bis(2-(1,3-dimethylbutylideneamino) ethyl)amino)-3-phenoxypropan-2-ol was not readily biodegradable under the conditions of the modified Sturm test presently performed. However, since results of the present test indicate that the pass level criterion was almost fulfilled for bottle A, results can be used to indicate inherent biodegradability.[1]

[1]OECD Guidelines For The Testing Of Chemicals. Revised Introduction To The OECD Guidelines For Testing Of Chemicals, Section 3, Part 1, Chapter 2.5, Paragraph 36. (adopted July 23 March 2006).