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Surface tension

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Reference
Endpoint:
surface tension
Type of information:
experimental study
Adequacy of study:
key study
Study period:
From 25 to 27 January 2016
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Justification for type of information:
The study was conducted according to an internationally recognised method, and under GLP. The test substance is adequately characterised. Therefore full validation applies.
Qualifier:
according to guideline
Guideline:
OECD Guideline 115 (Surface Tension of Aqueous Solutions)
Deviations:
no
Qualifier:
according to guideline
Guideline:
EU Method A.5 (Surface Tension)
Deviations:
no
Principles of method if other than guideline:
Not applicable
GLP compliance:
yes (incl. QA statement)
Remarks:
inspected on 13 and 14 October 2014 / signed on 08 April 2015
Type of method:
plate method
Key result
Surface tension:
53.07 mN/m
Temp.:
19.7 °C
Conc.:
61.15 mg/L
Remarks on result:
other: The concentration of the test item in the 90% saturated test solution was determined with to be 61.15 mg test item/L (based on analysis of dissolved organic carbon in the test solution).

Findings Main Study

The test item solution was held at constant temperature (20.0 ± 0.5 °C). 59 minutes after conclusion of the first measurement series, a second measurement series was performed for verification purposes.

The following values were recorded:

Table 1.-  Measured Values Test Item First Series

Measurement

Time

Mass

Surface Tension

Temperature

No

s

g

mN/m

°C

1

2.9

0.2175

53.06

19.7

2

5.9

0.2176

53.08

19.7

3

8.9

0.2176

53.08

19.7

4

11.9

0.2176

53.08

19.7

5

14.9

0.2177

53.11

19.7

6

17.9

0.2175

53.06

19.7

7

20.9

0.2174

53.03

19.7

8

23.9

0.2176

53.08

19.7

9

26.9

0.2175

53.06

19.7

10

29.9

0.2176

53.08

19.7

Mean

53.07

 

Standard Deviation

0.02

 

Table 2.-Measured Values Test Item Second Series

Measurement

Time

Mass

Surface Tension

Temperature

No

s

g

mN/m

°C

1

3.0

0.2189

53.40

19.7

2

5.9

0.2193

53.50

19.7

3

8.9

0.2189

53.40

19.7

4

11.9

0.2192

53.47

19.7

5

14.9

0.2192

53.47

19.7

6

17.9

0.2190

53.42

19.7

7

20.9

0.2192

53.47

19.7

8

23.9

0.2190

53.42

19.7

9

26.9

0.2189

53.40

19.7

10

29.9

0.2188

53.38

19.7

Mean

53.43

 

Standard Deviation

0.04

 

After the first and the second measurement series, the difference between mean values was less than 5%. Therefore no additional measurement series was required.

Analytical Determinations

TOC analysis of the filtrated test solution was performed using the carbon analyser TOC multi N/C 2100S, Analytik Jena. The test solution was measured in triplicate. The carbon analyser was calibrated with freshly prepared reference solutions containing potassium hydrogen phthalate (TC), sodium hydrogen carbonate and sodium carbonate (IC) every month. After every start, quality control samples were measured.

A value of 51.65 mg org. carbon/L was obtained, and the concentration of the test item was calculated from the measured DOC and the stated carbon content. The calibration data is presented in chapter15.

The carbon content in the test item had been determined under non-GLP-conditions in the laboratory Mikroanalytisches Labor Pascher (D-53424 Remagen) with 84.46 %w/w.

The concentration was therefore determined with 61.15 mg test item/L.

Result Test Item

During the specified period of time, no relevant changes in the surface tension were detected. Values ranging from 53.03 mN/m to 53.50 mN/m were recorded showing no relevant variations. The values of the single determinations show no significant difference (less than 5 % between mean values of the two measurement series)

As the determined surface tension of the test item was below 60 mN/m, the test item can be classified as surface active.

Validity

Literature value for the surface tension of H2O at 18.0oC: 73.05 mN/m (taken from Vargaftik et al., “International Tables of the Surface Tension of Water”, J. Phys. Chem. Ref. Data 12, 817, 1983).

The surface tension of the negative control was determined with 73.03 mN/m at 18.0°C, therefore showing a difference of 0.03% from the stated literature value. The difference lies within the accepted range of 1% deviation from literature value.

The values of the single determinations show no relevant difference (0.68% between mean values of the two measurement series). All measured values lay clearly below the threshold for surface tension which is stated in the guidelines.

The surface tension of the negative control was determined with a difference of 0.03 % from the stated literature value.

Therefore, the result of the test is considered valid and the test item is classified as “surface active” in a concentration of 61.15 mg/L (i.e. in a solution at 90%saturation obtained from an aqueous solution prepared with 1 g/L of test item slow-stirred for 72h).

Conclusions:
The surface tension of an aqueous solution of the test item was determined as 53.07 ± 0.02 mN/m at 19.7 °C.As all measured values were lower than 60 mN/m, test item has potential for surface activity. As the result is below the threshold value of 60mN/m, the substance is considered to have surface active potential under the experimental conditions based on EUA5 criteria.
However considering that the structure of the known constituents of the substance are not characteristic of true surfactants, that the dissolved part of the substance is probaby not representative of the whole substance and especially that it is not the intended use of the substance (i.e. not a desired property), this conclusion should be taken with caution.
Executive summary:

The surface tension of test item was determined according to EU method A.5 and OECD 115.

 

The concentration of the test item in the 90% saturated test solution was determined to be 61.15 mg test item/L (based on analysis of dissolved organic carbon in the test solution). The saturated solution was obtained from an aqueous solution prepared with 1 g/L of test item slow-stirred for 72h.

The surface tension of the negative control lay within the accepted range.

The surface tension of an aqueous solution of the test item was determined as 53.07 ± 0.02 mN/m at 19.7°C. One measurement series was performed for verification (after 58 minutes). No significant changes and thus no significant dependence on time were observed.
As all measured values were lower than 60 mN/m, the test item lwas classified as surface active.

Description of key information

Surface tension = 53.07 mN/m, at 90% saturation expected (61.15 mg/L)
As the result is below the threshold value of 60mN/m, the substance is considered to have surface active potential under the experimental conditions based on EUA5 criteria.

However considering that the structure of the known constituents of the substance are not characteristic of true surfactants, that the dissolved part of the substance is probaby not representative of the whole substance and especially that it is not the intended use of the substance (i.e. not a desired property), this conclusion should be taken with caution.

Key value for chemical safety assessment

Surface tension:
53.07
in mN/m at 20°C and concentration in mg/L:
61.15

Additional information

A fully reliable experimental study, conducted according to a recognized OECD/EU/ISO method and under GLP, is available. It is considered as a key study, and the result is retained as key value.

The concentration of the test item in the 90 % saturated test solution was determined to be 61.15mg/L (based on analysis of dissolved organic carbon in the test solution).