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Surface tension

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Endpoint:
surface tension
Type of information:
experimental study
Adequacy of study:
key study
Study period:
From 16 May 2012 to 06 December 2012
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Remarks:
The study was conducted according to internationally recognised guidelines, and under GLP. No deviation affected the quality of the study. The study was performed on the commercial product (aqueous solution) as the test item is manufactured and used in a liquid form.
Reason / purpose:
reference to same study
Qualifier:
according to
Guideline:
OECD Guideline 115 (Surface Tension of Aqueous Solutions)
Deviations:
no
Qualifier:
according to
Guideline:
EU Method A.5 (Surface Tension)
Deviations:
no
GLP compliance:
yes (incl. certificate)
Remarks:
2012-12-15
Type of method:
ring method
Key result
Surface tension:
>= 37.3 - <= 37.7 mN/m
Temp.:
20 °C
Conc.:
1 g/L
Remarks on result:
other: mean surface tension of the test item at 1 g/L of active substance in water (corresponding to 1.33 g solid content/L)

Results of calibration with demineralized water :

Assay No. 1

 

Assay No. 2

 

Assay No. 3

Temperature(°C)

19.7

 

Temperature(°C)

20.0

 

Temperature(°C)

20.0

Time

Surface tension (mN/m)

 

Time

Surface tension (mN/m)

 

Time

Surface tension( mN/m)

T0

78.2

 

T0

78.2

 

T0

78.6

T0+ 2 min

78.3

 

T0+ 2 min

78.1

 

T0+ 2 min

78.6

T0+ 4 min

78.3

 

T0+ 3 min

78.2

 

T0+ 3 min

78.6

Results

78.3

 

Results

78.2

 

Results

78.6

Mean surface tension of water : 78.4 ± 0.3 mN/m at 19.9°C

Calibration factor: 0.928

Results with test item at 1 g/l of active substance in deminseralized water:

Content of active substance in the test item : 36.2% w/w

Preparation of the solution : a quantity of 1.381 g of test item was weighed in a 500-mL volumetric flask and the volume was made up with demineralized water. The solution was manually shaking.

Assay No. 1

 

Assay No. 2

 

Assay No. 3

Temperature(°C)

20.0

 

Temperature(°C)

20.1

 

Temperature(°C)

20.1

Time

Surface tension (mN/m)

 

Time

Surface tension (mN/m)

 

Time

Surface tension (mN/m)

T0

42.4

 

T0

42.2

 

T0

42.2

T0+ 2 min

42.5

 

T0+ 3 min

42.2

 

T0+ 3 min

42.3

T0+ 3 min

42.5

 

T0+ 4 min

42.3

 

T0+ 5 min

42.3

The calculation of the surface tension is shown on the following table:

Assay

Measurements (mN/m)

Correction using Φb (mN/m)

Correction according to Harkins & Jordan table (mN/m)

State of equilibrium

1

42.5

39.3

37.5

2

42.3

3

42.3

Mean

42.4

Conclusions:
The mean surface tension of test item solution at 1g/L of active ingredient (corresponding to 1.33 g solid content/L): 37.5 ± 0.2 mN/m (corrected value). The test item was considered as surface-active in the experimental conditions used.
Executive summary:

The surface tension of the test item (= substance EC 939-455-3 in aqueous commercial product) was investigated in a GLP-compliant study performed in accordance with OECD Guideline 115 (Surface Tension of Aqueous Solutions) and EU Method A.5 (Surface Tension). The mean surface tension of a test item solution at 1g/L of active ingredient (corresponding to 1.33 g solid content/L) was 37.5 ± 0.2 mN/m. The test item was considered as surface-active in the experimental conditions used.

The study was performed on a commercial product (aqueous solution) as the substance EC 939-455-3 is manufactured and used in a liquid form.

Endpoint:
surface tension
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Justification for type of information:
1. HYPOTHESIS FOR THE ANALOGUE APPROACH
C8-C18 AAPHS and C12-18 AAPHS have the same functional groups, and general composition. The main variable resides in the alkyl chain distribution.

2. SOURCE AND TARGET CHEMICAL(S) (INCLUDING INFORMATION ON PURITY AND IMPURITIES)
Source chemical = C8-18 cocamidopropyl hydroxysultaine (EC 939-455-3).
Target chemical = C12-18 cocamidopropyl hydroxysultaine (EC 939-457-4).

3. ANALOGUE APPROACH JUSTIFICATION
The alkyl C-chain distribution of the source chemical significantly overlaps with the one of the target chemical, the C12-alkyl derivative being the major constituent in both chemicals. The structural differences in side C-chains is not expected to lead to significant differences on phys-chem properties.

4. DATA MATRIX
See "Documentation and scientific justification of the read-across approach" in section 13.2.
Reason / purpose:
read-across source
Key result
Surface tension:
>= 37.3 - <= 37.7 mN/m
Conc.:
1.33 other: solid content
Remarks on result:
other: read-across from EC 939-455-3
Conclusions:
By analogy with the source substance EC 939-455-3, a surface tension of 37.5 ± 0.2 mN/m was reported for the target substance 1-Propanaminium, N-(3-aminopropyl)-2-hydroxy-N,N-dimethyl-3-sulfo-, N-(C12-18(even numbered) acyl) derivs., hydroxides, inner salts (EC 939-457-4) at a concentration of 1.33 g solid content/L.

The source and target substances are both manufactured and used in a liquid form (aqueous solutions at a similar contentration range). The security physico-chemical parameters were therefore assessed from tests performed on aqueous solutions.

Description of key information

As the surface tension of the substance EC 939-457-4 have not been determined experimentally, a read-across approach was followed to fill in the endpoint. The surface tension of a structural analogue substance (= source substance EC 939-455-3) was investigated in a GLP-compliant study (Colombies, 2013) performed in accordance with OECD Guideline 115 (Surface Tension of Aqueous Solutions) and EU Method A.5 (Surface Tension). The mean surface tension of a solution at 1g/L of active ingredient (corresponding to 1.33 g solid content/L) was 37.5 ± 0.2 mN/m. The analogue substance was considered as surface-active in the experimental conditions used. By analogy, a surface tension of 37.5 ± 0.2 mN/m was reported for the target substance 1-Propanaminium, N-(3-aminopropyl)-2-hydroxy-N,N-dimethyl-3-sulfo-, N-(C12-18(even numbered) acyl) derivs., hydroxides, inner salts at a concentration of 1.33 g solid content/L (EC 939-457-4).

The alkyl C-chain distribution of the source substance EC 939-455-3 significantly overlaps with the one of the target substance EC 939-457-7, the C12-alkyl derivative being the major constituent in both chemicals. The structural differences in side C-chains is not expected to lead to significant differences on phys-chem properties.

Key value for chemical safety assessment

Surface tension:
37.5
in mN/m at 20°C and concentration in mg/L:
1 000

Additional information

The surface tension of the structural analogue substance (= source substance EC 939-455-3) was investigated in a GLP-compliant study (Colombies, 2013) performed in accordance with standard methods, without deviations. The study is considered as reliable (Klimisch 1) and was selected as key study for the endpoint of the target substance EC 939-457-4.