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Environmental fate & pathways

Biodegradation in water: screening tests

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Administrative data

biodegradation in water: ready biodegradability
Type of information:
experimental study
Adequacy of study:
key study
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
comparable to guideline study

Data source

Reference Type:
study report
Report date:

Materials and methods

Test guideline
equivalent or similar to guideline
OECD Guideline 301 B (Ready Biodegradability: CO2 Evolution Test)
GLP compliance:

Test material

Constituent 1
Reference substance name:
.beta.-Cyclodextrin, 2-hydroxypropyl cycloheptaamylose
.beta.-Cyclodextrin, 2-hydroxypropyl cycloheptaamylose
Constituent 2
Chemical structure
Reference substance name:
EC Number:
EC Name:
Cas Number:
Molecular formula:
Hill formula: (C42H70-nO35)(C3H7O)n; n(mittel)=5,25
Test material form:
solid: particulate/powder
migrated information: powder
Details on test material:
% Active: 93.5
Molecular weight: 1326-1400 g/mol
Solubility, in water: completely miscible
Color: white
Form: powder
TOC (mg TOC/mg active): 0.49
TCO2(mg CO2/mg active): 1.78
Storage Conditions: room temperature; dry, cool storage preferred
Expiration Date: 03/01/97
Date Received: 12/16/96

Study design

Oxygen conditions:
Inoculum or test system:
activated sludge (adaptation not specified)
Details on inoculum:
Twenty milliliters of the inoculum was added to all test flasks. The test flasks were placed on a rotary shaker, connected to the scrubbing train, and aerated overnight to purge the system of background CO2. After overnight aeration, three 4 oz.
CO2 absorber bottles (French squares) were filled with 100 mL of 0.024 N Ba(OH)2 and were connected in series to the exit air line of each test flask.

Activated sludge was collected from the DRWPCC on 13 January 1997. The sludge was screened through a 2 mm sieve prior to determining the total suspended solids (TSS). Based on this result approximately three litersof the sludge was adjusted to a target solids level
of 2,500 mg/L. The adjusted sludge was aerated in two semi-continuous activated sludge (SCAS)units until used on the following day in the preparation of the inoculum.
The inoculum was prepared for addition to the CO2 flasks as follows: Approximately 300 mL of activated sludge was collected from each SCAS unit, composited, and homogenized at medium speed in a blender for - 2 minutes. The homogenized sample was poured into a beaker and allowed to settle for ~ 30 minutes. The supematant· was decanted. and added to. the flasks at a concentration of 1% v/v. On the same day, a SPC was performed on the inoculum. The plates were incubated at test temperature. The result was 6.1 x 10*5 CFU/mL.
Duration of test (contact time):
34 d
Parameter followed for biodegradation estimation
Parameter followed for biodegradation estimation:
CO2 evolution
Details on study design:
- Composition of medium: 1,000 mg active/L stock solution was added to the duplicate flasks to achieve the specified concentration of 10 mg C/L
- Test temperature: 21.6-22.5°C
- pH: 7 +/- 1
- pH adjusted: yes
- Aeration of dilution water: yes
- Suspended solids concentration: 2,500 mg/L

- Culturing apparatus: flask
- Number of culture flasks/concentration:3

- Abiotic sterile control: yes
- Toxicity control: yes

Results and discussion

% Degradation
% degradation (CO2 evolution)
< 10
Sampling time:
34 d

Applicant's summary and conclusion

Validity criteria fulfilled:
Interpretation of results:
not inherently biodegradable
The C02 produced from the reference substance exceeded the 60% of theoretical within 14 days necessary to consider the test valid.
Executive summary:

A CO2 evolution test on test substance hydroxypropylated .beta.-cyclodextrin equivalent to OECD Guideline 301 A was conducted. This test was designed to determine the rate and extent of the ultimate biodegradation of the test substance under aerobic conditions.

The test apparatus consisted of five glass 4-liter Erlenmeyer flasks containing two liters of modified biochemical oxygen demand (BOD) water. Activated sludge was collected from the Downingtown Regional Water Pollution Control Center (DRWPCC) in Downingtown, Pennsylvania and used as the inoculum in this study. The sludge was not pre-exposed to the test substance in the laboratory prior to addition to the test flasks.

A dosing solution of hydroxypropylated .beta.-cyclodextrin was prepared in deionized (ASTM Type II) water at a concentration of 1,000 mg active/L. The solution was used to volumetrically dose duplicate flasks at a concentration of 10 mg C/L. Duplicate flasks receiving no test substance (blank control) and a single flask receiving sodium benzoate at a concentration of 10 mg C/L (reference· substance) were included in the test design. The flasks were placed on a rotary platform shaker and mixed at 110 ± 10 rpm for the duration of the study.

The CO2 produced in each flask reacted with 0.024 N Ba(OH)2 and precipitated as BaCO3.

The amount of CO2 produced was determined by titrating the remaining Ba(OH)2 with 0.05 N standardized hydrochloric acid (Hel). After 34 days the contents of the flasks were acidified with concentrated sulfuric acid (H2S04) and aerated overnight. One final titration was performed.

The C02 produced from the reference substance exceeded the 60% of theoretical within 14 days necessary to consider the test valid.