Registration Dossier

Administrative data

Endpoint:
hydrolysis
Type of information:
experimental study
Adequacy of study:
key study
Study period:
Start : 19 March 2012 Completion : 29 October 2012
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: GLP study without deficiencies

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2013
Report Date:
2013

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
OECD Guideline 111 (Hydrolysis as a Function of pH)
Deviations:
no
GLP compliance:
yes (incl. certificate)

Test material

Reference
Name:
Unnamed
Type:
Constituent
Test material form:
liquid: viscous
Details on test material:
Description: Brown highly viscous liquid
Batch: 966018
Purity: UVCB (treated as 100% pure)

Study design

Analytical monitoring:
yes
Details on sampling:
Samples were taken at t=0 hours and at 5 days. Blank buffer solutions containing a similar content of blank spiking solution were treated similarly as the test samples and analysed at t=0 hours.
Buffers:

Acetate buffer pH 4, 0.01 M:
solution of 16.7% 0.01 M sodium acetate and 83.3% 0.01 M acetic acid. The buffer contains 0.0009% (w/v) sodium azide.
Phosphate buffer pH 7, 0.01 M:
solution of 0.01 M potassium di-hydrogenphosphate adjusted to pH 7 using 1 N sodium hydroxide. The buffer contains 0.0009% (w/v) sodium azide.
Borate buffer pH 9, 0.01 M:
solution of 0.01 M boric acid and 0.01 M potassium chloride adjusted to pH 9 using 1 N sodium hydroxide. The buffer contains 0.0009% (w/v) sodium azide.

Results and discussion

Preliminary study:

At pH 4, pH 7 and pH 9 a degree of hydrolysis of < 10% was observed after 5 days. It demonstrated that the half-life time of the test substance at 25°C is > 1 year. According to the guideline, no further tests were required.
A small test substance peak was detected in the one of blank buffer samples at pH 4. The signal was below the lowest standard (2 μg/l) after a dilution by a factor of 2. Since no test substance was observed in the duplicate sample, it was not considered to derive from the buffer solution.
The mean recoveries of the test substance in the buffer solutions did not fall within the criterion range of 70-110% for non-labelled chemicals. The deviating recoveries are probably related to the low solubility of the test substance in the different buffer solutions. Since a hydrolysis study focuses on the relative concentration decrease of the test substance in time, the mean recoveries were considered acceptable and the analytical method was considered adequate for the support of the hydrolysis study on the test substance.
Transformation products:
not measured
Dissipation DT50 of parent compoundopen allclose all
Key result
pH:
4
Temp.:
25 °C
DT50:
> 1 yr
Type:
not specified
Key result
pH:
7
Temp.:
25 °C
DT50:
> 1 yr
Type:
not specified
Key result
pH:
9
Temp.:
25 °C
DT50:
> 1 yr
Type:
not specified

Any other information on results incl. tables

Preliminary test – hydrolysis of DNNSA at pH 4, pH 7 and pH 9

pH

Sampling time

Analyzed Concentration

μg/L

% Hydrolysis

Individual

% Hydrolysis

Mean

4

0 hours

28.0, 26.2

 

 

 

5 days

30.6, 24.9

-13, 8.1

-2.5

7

0 hours

66.3, 77.5

 

 

 

5 days

65.3, 64.1

1.6, 3.4

2.5

9

0 hours

26.9, 27.5

 

 

 

5 days

27.8, 25.6

-2.3, 6.0

1.9

Applicant's summary and conclusion

Conclusions:

The preliminary test (Tier 1) was performed for the determination of the rate of hydrolysis of
di C8-C10, branched, C9 rich, alkylnaphthalene sulphonic acid (DNNSA) at pH values normally found in the environment (pH 4-9).
At each pH value a degree of hydrolysis of < 10% was observed after 5 days. According to the guideline, performance of the main study (Tier 2) was not required.
The half-life time of the test substance at 25°C was:
t½ pH 4: > 1 year
pH 7 > 1 year
pH 9 > 1 year
Executive summary:

The rate of hydrolysis of di C8-C10, branched, C9 rich, alkylnaphthalene sulphonic acid (DNNSA) as a function of pH was determined at pH values normally found in the environment (pH 4-9). A high performance liquid chromatographic method with tandem mass spectrometric detection (HPLC-MS/MS) for the quantitative analysis of the test substance in water was developed and employed in the assessment. For a Preliminary test, the buffer solutions were filter-sterilised through a 0.2 μm FP 30/0.2 CA-S filter (Whatman, Dassel, Germany) and transferred into a sterile vessel. To exclude oxygen, nitrogen gas was purged through the solution for 5 minutes. The test substance was spiked to the solutions at a target concentration of 50 μg/l using a spiking solution in acetonitrile. For each sampling time, duplicate sterile vessels under vacuum were filled with 6 ml test solution and placed in the dark in a temperature controlled environment at 49.9°C ± 0.1°C.

The concentration of the test substance in the test samples was determined immediately after preparation (t=0) and after 5 days. The samples taken at t=5 days were cooled to room temperature using running tap water. The samples were diluted in a 1:1 (v:v) ratio with acetonitrile and analysed.

Blank buffer solutions containing a similar content of blank spiking solution were treated similarly as the test samples and analysed at t=0.

The pH of each of the test solutions (except for the blanks) was determined at each sampling time.

At pH 4, pH 7 and pH 9 a degree of hydrolysis of < 10% was observed after 5 days. It demonstrated that the half-life time of the test substance at 25°C is > 1 year. According to the guideline, no further tests were required.

A small test substance peak was detected in the one of blank buffer samples at pH 4. The signal was below the lowest standard (2 μg/l) after a dilution by a factor of 2. Since no test substance was observed in the duplicate sample, it was not considered to derive from the buffer solution.

The mean recoveries of the test substance in the buffer solutions did not fall within the criterion range of 70-110% for non-labelled chemicals. The deviating recoveries are probably related to the low solubility of the test substance in the different buffer solutions. Since a hydrolysis study focuses on the relative concentration decrease of the test substance in time, the mean recoveries were considered acceptable and the analytical method was considered adequate for the support of the hydrolysis study on the test substance.

The half-life time of DNNSA at 25°C was:

t½ pH 4: > 1 year

pH 7 > 1 year

pH 9 > 1 year