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Physical & Chemical properties

Surface tension

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Reference
Endpoint:
surface tension
Type of information:
experimental study
Adequacy of study:
key study
Study period:
From June 26 to July 08, 2009
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Remarks:
The study was conducted according to a method recommended in international standards. No deviation was reported. The substance is considered to be adequately characterised with its purity. Therefore full validation applies.
Reason / purpose:
reference to other study
Qualifier:
according to
Guideline:
OECD Guideline 115 (Surface Tension of Aqueous Solutions)
Version / remarks:
27 July 1995
Deviations:
no
Qualifier:
according to
Guideline:
EU Method A.5 (Surface Tension)
Version / remarks:
Regulation (EC) No 440/2008
Deviations:
no
Qualifier:
according to
Guideline:
other: ISO 304
Principles of method if other than guideline:
Not applicable
GLP compliance:
yes (incl. certificate)
Remarks:
UK GLP compliance programme (inspected on August 19, 2008 / signed on March 4, 2009)
Type of method:
ring method
Specific details on test material used for the study:
Storage conditions: approximately 4ºC in the dark under nitrogen.
Key result
Surface tension:
45 mN/m
Temp.:
21.6 °C
Conc.:
1.01 g/L

Table 4.10/1: Surface tension – results

Calibration with water:

Mean reading : 72.36 mN/m at 21.6°C (n=7)

Reference value (literature): 72.47 mN/m

Correction factor = 72.47/72.36 = 1.002

 

Test substance solution:

Time (mins)

 

Reading (mN/m)

 

Temperature (ºC)

90

44.5

21.6

100

45.0

21.6

110

45.0

21.6

120

45.0

21.6

130

45.0

21.6

155

45.0

21.6

 

Mean reading : 44.9 mN/m

Surface tension = reading x calibration factor = 44.9 x 1.002 = 45.0 mN/m

Temperature : 21.6 ± 0.5 °C

pH of sample solution : 5.34

Discussion

Substances having a surface tension below 60 mN/m are regarded as being surface-active. Therefore the value of 45.0 mN/m determined for the test material indicates that the test material is surface active. However, the test material does not have a typical surfactant structure (polar head with carbon chain).

Therefore, to provide further information, an assessment of the emulsification properties of the test material was carried out with the sample solution used for the surface tension determination and partitioned with an equal amount of water saturated n-octanol. Observations showed that after the two immiscible phases separated, an emulsion was visible at the phase boundary. In addition, after the sample solution had been shaken vigorously, foam was observed to persist at the surface of the liquid.

Therefore the emulsification and persistent foam properties of the test material confirm the test material can be considered to be surface active.

Conclusions:
According to EU A5 criteria, as the result is below the threshold value of 60 mN/m, the substance is considered to have surface-active potential under the experimental conditions.
Executive summary:

The surface tension of the test substance was measured under GLP according to OECD 115/EU A5 guidelines, ring method. Six readings were recorded, and the mean value was corrected with calibration factor from water.

The surface tension of the test substance is 45.0 mN/m, at 1.01 g/L and 21.6°C.

Surface-active properties were confirmed from visual assessment (emulsification, foaming) when mixing the test solution with octanol.

Description of key information

According to EU A5 criteria, as the result is below the threshold value of 60 mN/m, the substance is considered to have surface-active potential under the experimental conditions. This was confirmed by visual assessment, however, the structure is not characteristic of a true surfactant, and it is not the intended use of the substance (i.e. not a desired property).

Key value for chemical safety assessment

Surface tension:
45
in mN/m at 20°C and concentration in mg/L:
1 000

Additional information

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