D-Gluconic acid, δ-lactone, reaction products with propanolamine

Biodegradation in water: screening tests

Link to relevant study record(s)

Reference

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

key study

Study period:

October 5 to November 3, 2017

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

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

Version / remarks:

adopted July 17, 1992

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Specific details on test material used for the study:

Test Item Name FiberHance BM Solution
Chemical name (REACH): Reaction mass of 3-hydroxypropan-1-aminium D-gluconate and N-(3-hydroxypropyl)-D-gluconamide
Batch/Lot Number 0002098907
CAS Name D-Gluconic acid, δ-lactone, reaction products with propanolamine
CAS Number (CAS RN) 2060570-71-8
Analysed Purity 49.8% w/w
Supplied to JRF by Ashland Services B.V.
Date of Manufacture January 12, 2017
Date of Expiry January 12, 2018
Appearance Clear yellow liquid

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic, non-adapted

Details on inoculum:

- Source of inoculum/activated sludge (e.g. location, sampling depth, contamination history, procedure): activated sludge freshly obtained from a municipal sewage treatment plant: 'Waterschap Aa en Maas', 's-Hertogenbosch, The Netherlands, receiving predominantly domestic sewage.
- Storage conditions:
- Pretreatment: The freshly obtained sludge was kept under continuous aeration until further treatment. Before use, the sludge was allowed to settle (30 minutes) and the supernatant liquid was used as inoculum at the amount of 10 mL/L of mineral medium.
- Concentration of sludge: The concentration of suspended solids was determined to be 4.13 g/L.

Duration of test (contact time):

28 d

Initial conc.:

12 mg/L

Based on:

TOC

Parameter followed for biodegradation estimation:

CO2 evolution

Details on study design:

TEST CONDITIONS
- Composition of medium:
Milli- RO water Tap-water purified by reverse osmosis (Milli- RO) and subsequently passed over activated carbon.
 
Stock solutions of mineral components
A) 8.50 g KH2PO4
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.
- Test vessels 2 litre brown coloured glass bottles.
- 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.
- Test temperature: between 22 and 24°C.
- pH: 7.7
- pH adjusted: no

TEST SYSTEM
- Culturing apparatus:
- Number of culture flasks/concentration:
- Method used to create aerobic conditions:
- Method used to create anaerobic conditions:
- Measuring equipment:
- Test performed in closed vessels due to significant volatility of test substance:
- Test performed in open system:
- Details of trap for CO2 and volatile organics if used:
- Other:

Determination of CO2
Experimental CO2 production: The CO2 produced in each test bottle reacted with the barium hydroxide in the gas scrubbing bottle and precipitated out as barium carbonate. The amount of CO2 produced was determined by titrating the remaining Ba(OH)2 with 0.05 M standardized HCl (1:20 dilution from 1 M HCl (Titrisol® ampoule), Merck, Darmstadt, Germany).
Measurements: Titrations were made every second or third day during the first 10 days, and thereafter at least every fifth day until day 28, for the inoculum blank and test item. Titrations for the positive and toxicity control were made over a period of at least 14 days. Each time the CO2-absorber nearest to the test bottle was removed for titration; each of the remaining two absorbers were moved one position in the direction of the test bottle. A new CO2-absorber was placed at the far end of the series. Phenolphthalein (1% solution in ethanol, Merck) was used as pH-indicator.
On the penultimate day, the pH of respective test suspensions was measured and 1 mL of concentrated HCl (37%, Merck) was added to the bottles of the inoculum blank and test suspension. The bottles were aerated overnight to drive off CO2 present in the test suspension. The final titration was made on day 15 (positive and toxicity control) and on day 29 (remaining vessels).
Theoretical CO2 production: The theoretical CO2 production was calculated from the results of the TOC-analysis.

Acceptability of the Test
1. The positive control item was biodegraded by at least 60% (83%) within 14 days.
2. The difference of duplicate values for %-degradation of the test item was always less than 20 (≤ 13%).
3. The total CO2 release in the blank at the end of the test did not exceed 40 mg/L (56.2 mg CO2 per 2 litres of medium, corresponding to 28.1 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, 12 mg TOC/L).
Since all criteria for acceptability of the test were met, this study was considered to be valid.

Critical computerized systems were used:
System name Version No. Description of Data Collected and/or Analyzed
REES Centron SQL 2.0 Temperature, relative humidity and/or atmospheric pressure monitoring
Shimadzu TOC-Control L 2.10 System control, data acquisition and processing

Reference substance:

acetic acid, sodium salt

Remarks:

a final concentration of 40 mg sodium acetate per litre (12 mg TOC/L)

Key result

Parameter:

% degradation (CO2 evolution)

Value:

>= 65 - <= 67

Sampling time:

15 d

Key result

Parameter:

% degradation (CO2 evolution)

Value:

>= 71 - <= 75

Sampling time:

29 d

Comparison of Biodegradation of the Test Item in Bottles A and B:

Day	Biodegradation (%)
	Bottle A	Bottle B	Mean A and B	∆ A-B^1)
1	0	0	0	0
4	5	12	9	7
6	11	22	17	11
8	18	31	25	13
11	44	52	48	8
15	67	65	66	2
18	70	71	71	1
22	71	74	73	3
25	71	75	73	4
29^2)	71	75	73	4
29^2)	71	75	73	4
29^2)	71	75	73	4
^1): Absolute difference in biodegradation between bottles A and B ^2): Biodegradation is ended on day 28 by addition of HCl. Therefore, differences observed on day 29 are actually differences of day 28.

Validity criteria fulfilled:

yes

Interpretation of results:

readily biodegradable

Conclusions:

In conclusion, FiberHanceTM BM solution was readily biodegradable under the conditions of the modified Sturm test presently performed.

Description of key information

Reaction mass of 3-hydroxypropan-1-aminium D-gluconate and N-(3-hydroxypropyl)-D-gluconamide is readily biodegradable and nontoxic to microorganisms in the inoculum. Based on the degradation curve in the CO2 -evolution test, more than 60% degradation is reached within the 10 -day window.

Key value for chemical safety assessment

Biodegradation in water:

readily biodegradable

Additional information

Based on the QSAR program BIOWIN, the main constituents of the reaction mass are potentially rapidly degradable. Based on the degradation curve in a 28 -day closed bottle test (OECD 301D), more than 60% degradation was expected to be reached after 35 days. In an additional modified Sturm test (OECD 301B), more than 60% degradation was reached within the 10 -day window. Due to the stringency of the OECD 301 screening tests, a positive result for ready biodegradability in any of these tests can be considered as indicative of rapid and ultimate degradation in most environments including biological STPs.