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Surface tension

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Reference
Endpoint:
surface tension
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: see 'Remark'
Remarks:
Followed guideline and GLP requirements; Surface tension was not corrected using Harkins-Jordan correction table as the correction is not needed for the apparatus tested. Once calibrated, the ring and balance assembly used gave a direct reading for surface tension that was within the required accuracy (+/- 0.5 mN/m)
Qualifier:
equivalent or similar to guideline
Guideline:
EU Method A.5 (Surface Tension)
Deviations:
yes
Remarks:
Surface tension was not corrected using Harkins-Jordan correction table as the correction is not needed for the apparatus tested.
Qualifier:
according to guideline
Guideline:
other: ISO 304 Ring Method
GLP compliance:
yes (incl. QA statement)
Type of method:
ring method
Surface tension:
ca. 59.6 mN/m
Temp.:
22.6 °C
Conc.:
0.092 g/L
Remarks on result:
other: Test article considered to be surface-active

Readings, times and temperatures for Sample Analysis

Time (minutes)

Reading (mN/m)

Temperature (degrees C)

174

57.0

22.6

179

59.0

22.6

187

59.5

22.6

193

59.5

22.6

200

59.5

22.6

209

59.5

22.6

Mean reading:         59.5 mN/m (last 4 readings)

Surface tension = reading x calibration factor

                        = 59.5 x 1.0002 = 59.6 mN/m

Temperature:   = 22.6 +/- 0.5 degrees C

pH of sample solution = 9.4

Test items giving a solution surface tension of lower than 60 mN/m are interpreted as being surface-active by Method A5. Using SPARC v. 4.5, the test item gave calculated pKa's of 9.98 and 10.81; therefore the test item would be ionized at the pH of the test solution. thus, since the ionized test item has a typical surfactant strucute ie polar head attached to a carbon chain, the test item was expected to be surface-active.

Conclusions:
A ring test yielded a value of 59.6 mN/m (9.25 x 10-2 g/l) at 22.6 +/- 0.5 degrees C for the test article. The test article was considered to be surface active by definition of Method EC A5, and based on it’s chemical structure. 
Executive summary:

A test using a ring method based on ISO 304, designed to be compatible with Method A5 “Surface Tension” of Commission Regulation (EC) No. 440/2008 yielded a value of 59.6 mN/m (9.25 x 10-2 g/l) at 22.6 +/- 0.5 degrees C for the test article. The test article was considered to be surface active by definition of Method EC A5, and based on it’s chemical structure. 

Test items giving a solution surface tension of lower than 60 mN/m are interpreted as being surface-active by Method A5. Using SPARC v. 4.5, the test item gave calculated pKa's of 9.98 and 10.81; therefore the test item would be ionized at the pH of the test solution. Thus, since the ionized test item has a typical surfactant structure ie polar head attached to a carbon chain, the test item was expected to be surface-active.

Description of key information

A test using a ring method based on ISO 304, designed to be compatible with Method A5 “Surface Tension” of Commission Regulation (EC) No. 440/2008 yielded a value of 59.6 mN/m (9.25 x 10-2 g/l) at 22.6 +/- 0.5 degrees C for the test article. The test article was considered to be surface active by the strict definition of Method EC A5 (<60 mN/m), and based on it’s chemical structure. 
Moreover, using SPARC v. 4.5, the test item gave calculated pKa's of 9.98 and 10.81; therefore the test item would be ionized at the pH of the test solution. Thus, since the ionized test item has a typical surfactant structure (ie. polar head attached to a carbon chain), the test item was expected to be surface-active.

Key value for chemical safety assessment

Surface tension:
59.6
in mN/m at 20°C and concentration in mg/L:
92.5

Additional information