Bis(trimethoxysilylpropyl)amine

Biodegradation in water: screening tests

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

supporting study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: guideline study with acceptable restrictions) because only two replicates were used (guideline suggests at least ten), and the results are somewhat unusual (20% at 5d, 11% at 15d, 17% at 28d)

Qualifier:

according to guideline

Guideline:

OECD Guideline 301 D (Ready Biodegradability: Closed Bottle Test)

Qualifier:

according to guideline

Guideline:

other: EEC Directive 67/548 Annex V C6 as published in 84/449/EEC.

GLP compliance:

yes

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, non-adapted

Details on inoculum:

- Source of inoculum/activated sludge: The aeration stage of the HRC Limited sewage treatment plant treating predominantly domestic sewage.

Duration of test (contact time):

28 d

Details on study design:

TEST CONDITIONS
- Composition of medium: Standard nutrient medium
- Test temperature: 21 ± °C
- Continuous darkness: yes


TEST SYSTEM
- Culturing apparatus: 280 ml BOD bottles (darkened glass) with ground glass stoppers.
- Number of culture flasks/concentration: 2
- Measuring equipment: Yellow Springs BOD Probe (model 54)



SAMPLING
- Sampling frequency: day 0, 5, 15, 28 h
- Sampling method: Dissolved oxygen measurements


CONTROL AND BLANK SYSTEM
- Inoculum blank: yes

Reference substance:

benzoic acid, sodium salt

Parameter:

% degradation (O2 consumption)

Value:

17

Sampling time:

28 d

Remarks on result:

other: 11-20 %

Results with reference substance:

Sodium benzoate attained 89% degradation within 28 days.

Test substance: Silane Y-9492.

Test concentration : 3 mg/l.

Oxygen depletion (28 days): 0.850 mgO,/l.

Theoretical oxygen demand( ThOD): 5.06 mgO2/l.

Percentage biodegradation (28 days): 11 - 20%.

Interpretation of results:

other: not readiliy biodegradable

Conclusions:

The study conducted according to OECD guideline 301 D showed that the substance is not readily biodegradable (17% biodegradation) within 28 d.

Reference 2

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

key study

Study period:

09 May - 06 Jun 2012

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

other: Method for Testing the Biodegradability of Chemical Substances by Microoiganisms, Ministry of the Environment, Japan

GLP compliance:

yes

Oxygen conditions:

aerobic

Inoculum or test system:

other: samples from 10 locations in Japan: surface water, surface soil of rivers, lakes, inland sea and return sludges from sewage plants

Details on inoculum:

- Source of inoculum/activated sludge: from 10 locations in Japan (samples were from surface water, surface soil of rivers, lakes, inland sea and return sludges from sewage plants)
- Laboratory culture: activated sludge, was prepared and controlled in this laboratory
- Method of cultivation: synthetic sewage was prepared in dissolved glucose, peptone, and potassium dihydrogenphosphate in purified water. The pH of the solution was adjusted to 7.0 ± 1.0. Cultivation took place for 19 h after the synthetic sewage was added.
- Concentration of sludge: 30 mg/L

Duration of test (contact time):

28 d

Initial conc.:

100 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation:

DOC removal

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

TEST CONDITIONS
- Composition of medium: basal culture medium (in accordance with Japanese Industrial Standards (JIS) K 0102-2010, section 21) of solution. The pH of this solution was then adjusted to 7.0.
- Additional substrate: 2.74 mL activated sludge
- Test temperature: 25 ± 1 °C
- pH: water + test item: 9.5 - 9.8, sludge + test item: 7 - 7.7
- pH adjusted: yes
- Suspended solids concentration in each vessel: 30 mg/L
- Continuous darkness: yes

TEST SYSTEM
- Volume of test solution: 300 mL
- Number of culture flasks/concentration: 3
- Measuring equipment: closed system oxygen consumption measuring apparatus
- Absorbent for CO2 used: absorbent for carbon dioxide: soda lime
- Stirring: each test solution was stirred by a stirrer

SAMPLING
- Sampling frequency: appearance of the test solution was observed once a day, BOD of the test solutions was measured continuously, cultivation temperature was measured and recorded once a day, at the end of the cultivation, dissolved organic carbon (DOC) in the test solutions was determined, methanol and N,N- bis (3-trihydroxysilylpropyl) amine as converted products in the test solutions were analyzed quantitatively
- Sampling method: 40 mL sample was taken out of the 300 mL test solution for analysis (for more detail see section details on analytical methods)

CONTROL AND BLANK SYSTEM
- Control (water + test item): 1
- Inoculum control: 1
- Control blank: 1

Reference substance:

aniline

Parameter:

% degradation (DOC removal)

Value:

48

Sampling time:

28 d

Parameter:

other: BOD

Value:

41

Sampling time:

28 d

Details on results:

All of the test item was hydrolyzed rapidly and converted to methanol and N,N-bis (3-trihydroxysilylpropyl) amine under the test conditions of this study. Methanol was biodegraded while N,N-bis (3-trihydroxysilylpropyl) amine remained in the test solution.

Results with reference substance:

79% biodegradation of aniline by BOD after 14 d.

The test item was hydrolyzed rapidly in water and therefore the % biodegradation of the test item could not be calculated.

Table 1: Analytical results of the test solution at the end of the test.

		Water + Test item	Sludge + Test item			Theoretical amount
		Vessel No. 1	Vessel No. 2	Vessel No. 3	Vessel No. 4
Residual DOC amount*	mg C	12.9	6.8	6.6	6.6	12.7
	%	102	53	52	52	-
Produced amount of Methanol (GC)	mg	17.5	0	0	0	17
	%	103	0	0	0	-
Produced amount of Silanol form (LC-MS)	mg	21.6	22.9	21.8	21.7	22.8
	%	95	100	96	95	-
BOD**	mg	1.1	22.4	24.6	22.2	55.9

* The value of the test solution (control blank) was substracted from the values of the test solutions (sludge + test item)

** The value of the test solution (control blank) was substracted from the values of the test solutions (sludge + test item)

*** The dermination of the test item could not be performed because the test item is hydrolyzed rapidly in water

Table 2: % biodegradation after 28 d.

	Vessel 2	Vessel 3	Vessel 4	Average
% biodegradation by BOD	40	44	40	41
% biodegradation by DOC	48	49	49	48
% biodegradation of test item (HPLC)	The determination of the test item could not be performed because the test item is hydrolyzed rapidly in water. Therefore the % biodegradation of the test item was not calculated

The substance hydrolyses to methanol and a silanol hydrolysis product. Quantitative analysis showed 103% methanol production in the solution "water + test item" and 0% methanol in the solution "sludge + test item". On the other hand 95% production of the silanol hydrolysis product was observed in the solution "water + test item" and 95 -100% in the solution "sludge + test item". These results suggest that methanol is readily biodegradable whereas silanol does not biodegrade.

Validity criteria fulfilled:

yes

Interpretation of results:

not readily biodegradable

Conclusions:

The test item was shown to hydrolyze rapidly to methanol and bis(hydromethoxysilylpropyl)amine under test conditions. Methanol was biodegraded while bis(hydromethoxysilylpropyl)amine remained in the test solution. The test item is not readily biodegradable. 41% biodegradation took place based on BOD and 48% based on DOC measurments.

Description of key information

Not readily biodegradable (48% biodegradation within 28 d).

Additional information

Two studies are available testing the biodegradation potential of bis(trimethoxysilylpropyl)amine (CAS 82985-35 -1).

The key study was conducted according to the Method for Testing the Biodegradability of Chemical Substances by Microorganisms, Ministry of the Environment, Japan and GLP (2012). A mix of water, surface soil of rivers, lakes, inland sea and return sludges from 10 locations in Japan was used as inoculum and was exposed to 100 mg/L test item for 28 d. DOC and oxygen consumption were monitored for the estimation of biodegradation. A preliminary test confirmed that the substance had hydrolized in the test solution after 0.5 h. The biodegradation reached a maximum of 48% based on DOC removal or 41% based on BOD after 28 d. The two hydrolysis products, methanol and bis(trihydroxysilylpropyl)amine were analytically monitored by GC and LC-MS, respectively during the test. The analytical results suggest that the observed biodegradation is coupled completely to the biodegradation of the hydrolysis product methanol while the silanol hydrolysis product does not biodegrade. The substance is not readily biodegradable.

The supporting study was performed according to the OECD guideline 301 D and GLP (1989). Activated sludge from a sewage treatment plant was used as inoculum. The test substance attained between 11 and 20% degradation after 28 days, identifying that the substance is not readily biodegradable.