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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:
Testing was conducted between 05 December 2011 and 20 February 2012.
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: see 'Remark'
Remarks:
Study conducted in compliance with agreed protocols, with no or minor deviations from standard test guidelines and/or minor methodological deficiencies, which do not affect the quality of the relevant results. The study report was conclusive, done to a valid guideline and the study was conducted under GLP conditions.
Qualifier:
according to
Guideline:
EU Method A.5 (Surface Tension)
Deviations:
yes
Remarks:
The surface tension result was not corrected using the Harkins-Jordan correction table.
Qualifier:
according to
Guideline:
OECD Guideline 115 (Surface Tension of Aqueous Solutions)
Deviations:
yes
Remarks:
The surface tension result was not corrected using the Harkins-Jordan correction table.
Principles of method if other than guideline:
The surface tension result was not corrected using the Harkins-Jordan correction table as the correction is not applicable to the apparatus used. Once calibrated, the balance and ring assembly used in this test give a direct reading for surface tension that is within the required accuracy
(± 0.5 mN/m); this is as a result of the reduced ring dimensions.
This deviation has been considered not to have affected the integrity of the study.
GLP compliance:
yes (incl. certificate)
Type of method:
ring method
Specific details on test material used for the study:
Sponsor's identification: Amyl Salicylate
Description: Clear colourless liquid
Chemical name(s): Pentyl 2-hydroxybenzoate and 3-Methylbutyl 2-hydroxybenzoate
CAS Number(s): 2050-08-0 and 87-20-7
Purity: 99.99 % (sum of the isomers)
Batch number: PE00022143
Label: AMYL SALICYLATE Batch PE00022143 Expiry date: 19.08.2012 Net weight 0.106KG
Date received: 03 October 2011
Expiry date: 19 August 2012
Storage conditions: Room temperature in the dark

The integrity of supplied data relating to the identity, purity and stability of the test item is the responsibility of the Sponsor. A Certificate of Analysis, provided by the Sponsor, is presented in the attachment "CofA".
Surface tension:
>= 71.1 - <= 72.6 mN/m
Temp.:
19 °C
Conc.:
0.003 g/L

Results

Sample solution concentrations

The mean total peak areas relating to the standard and sample solutions are shown in the following table:

Table 4.3

Solution

Mean Total Peak Area Ratio

Standard 10.0 mg/l

0.28379

Standard 9.94 mg/l

0.26371

Sample A

0.78698

Sample B

0.99777

Sample solution concentrations:
2.87 x 10-3g/l (Sample A) and 3.64 x 10-3g/l (Sample B).

Calibration factor (f)

The readings, temperatures and the corresponding calibration factors for glass double-distilled water are shown in the following tables:

Table 4.4 – Sample A

Reading (mN/m)

Temperature (ºC)

Literature Value (mN/m)

Calibration Factor

73.0

19.0

72.87

0.998

73.0

19.0

72.87

0.998

72.5

19.0

72.87

1.005

72.5

19.0

72.87

1.005

73.0

19.0

72.87

0.998

73.0

19.0

72.87

0.998

Mean Calibration Factor = 1.000


Table 4.5 – Sample B

Reading (mN/m)

Temperature (ºC)

Literature Value (mN/m)

Calibration Factor

72.5

19.0

72.87

1.005

72.5

19.0

72.87

1.005

72.5

19.0

72.87

1.005

72.5

19.0

72.87

1.005

72.5

19.0

72.87

1.005

72.5

19.0

72.87

1.005

Mean Calibration Factor = 1.005

Sample solution readings

The readings, times and temperatures for the sample solutions are shown in the following tables:

Table 4.6 – Sample A

Time (mins)

Reading (mN/m)

Temperature (ºC)

125

73.0

19.0

133

72.5

19.0

139

72.5

19.0

147

72.5

19.0

153

72.5

19.0

Mean reading                :   72.6 mN/m
Surface tension            = reading x calibration factor
                                         = 72.6 x 1.000
                                         = 72.6 mN/m
Temperature                  :   19.0 ± 0.5 ºC
pH of sample solution  :   5.6


Table 4.7 – Sample B

Time (mins)

Reading (mN/m)

Temperature (ºC)

197

71.0

19.0

202

71.0

18.8

207

71.5

19.0

212

71.0

19.0

216

71.0

19.0

Mean reading                :   71.1 mN/m
Surface tension            = reading x calibration factor
                                         = 71.1 x 1.005
                                         = 71.5 mN/m
Temperature                  :   19.0 ± 0.5 ºC
pH of sample solution  :   5.7

Validation

The linearity of the detector response with respect to concentration was assessed over the concentration range of 0 to 32.6 mg/l. This was satisfactory with a correlation coefficient (r2) of 1.000 being obtained.

Recovery of analysis of the sample extraction procedure was assessed and proved suitable for the test. At a sample concentration of 1.25 mg/l, a mean percentage recovery of 103 % was obtained (range: 102 to 103 %). Concentrations have not been corrected for recovery of analysis.

Discussion

Test items showing a surface tension below 60 mN/m are regarded as being surface-active by EC Method A5.

During preliminary testing, it was noted that ultra-centrifugation of the sample solutions did not clean up the sample solutions of excess, undissolved test item. Therefore, it was considered more applicable to slowly filter the sample solutions through a 0.2µm Nylon membrane filter. However, even after filtration, the sample solutions were noted to contain small amounts of excess, undissolved test item. As a result of this, it was considered more appropriate to report the test solutions as approximately 90 % saturated.

As the surface tension results indicated that the test item was not surface-active, it was anticipated that the small amounts of undissolved test item in the saturated solutions had a negligible impact on the surface tension readings of the 90 % “saturated” solutions.

As the test item was proposed to be sensitive to light, testing was carried out under non-actinic lighting only.

Conclusions:
The surface tension of an approximately 90 % saturated solution (2.87 x 10-3 to 3.64 x 10-3 g/l, determined by GC) of the test item was determined to be in the range 71.1 to 72.6 mN/m at 19.0 ± 0.5 °C.
Executive summary:

Method

The determination was carried out using a White Electrical Institute Co. Ltd. torsion balance for surface and interfacial tension measurements and a procedure based on the ISO 304 ringthod. With the exception of the following deviation, the experintal procedure used was designed to be compatible with that specified in Method A5 Surface Tension of Commission Regulation (EC) No 440/2008 of 30 May 2008 and Method 115 of the OECD Guidelines for the Testing of Chemicals, 27 July 1995.

§    The surface tension result was not corrected using the Harkins-Jordan correction table as the correction is not applicable to the apparatus used. Once calibrated, the balance and ring assembly used in this test give a direct reading for surface tension that is within the required accuracy (± 0.5 mN/m); this is as a result of the reduced ring dimensions.

This deviation has been considered not to have affected the integrity of the study.

Conclusion

The surface tension of an approximately 90 % saturated solution (2.87 x 10-3to 3.64 x 10-3g/l, determined by GC) of the test item was determined to be in the range 71.1 to 72.6 mN/mat 19.0 ± 0.5 °C. The test item was considered not to be surface-active.

Description of key information

Surface tension is 71.1 to 72.6mN/m at 19.0 ± 0.5 °C.

Key value for chemical safety assessment

Surface tension:
71.1
in mN/m at 20°C and concentration in mg/L:
2.87

Additional information

The surface tension of an approximately 90 % saturated solution (2.87 x 10-3 to 3.64 x 10-3 g/l, determined by GC) of the test item was determined to be in the range 71.1 to 72.6 mN/m at 19.0 ± 0.5 °C. The test item was considered not to be surface-active since the surface tension was greater than 60 mN/m.