Octan-1-ol

Surface tension

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

surface tension

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

study well documented, meets generally accepted scientific principles, acceptable for assessment

Principles of method if other than guideline:

Interfacial tensions were measured using a platinum Wilhelmy plate.

GLP compliance:

no

Type of method:

plate method

Surface tension:

19.8 mN/m

Temp.:

22.5 °C

Conc.:

440.8 mg/L

Remarks on result:

other: Results were converted to mg/L by the authors of this summary using the water solubility of 1-octanol = 551 mg/L.

Conclusions:

A surface tension value of 19.8 mN/m at 22.5°C and a concentration of 440.8 mg/L was determined in a reliable study conducted according to generally accepted scientific principles. The result is considered to be reliable.

Reference 2

Endpoint:

surface tension

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

study well documented, meets generally accepted scientific principles, acceptable for assessment

Principles of method if other than guideline:

Surface tension measurements were made using a drop volume tensiometer. The technique measures the volume of a drop detaching from a capillary with inner radius 1.08mm.

GLP compliance:

no

Type of method:

other: drop volume tensiometer

Key result

Surface tension:

35.54 mN/m

Temp.:

298.15 K

Conc.:

361.77 mg/L

Remarks on result:

other: Results were converted to mg/L by the authors of this summary using MW 1-octanol = 130.23

Conclusions:

A surface tension value of 35.54 mN/m at 25°C and a concentration of 361.77 mg/L was determined in a reliable study conducted according to generally accepted scientific principles. The result is considered to be reliable.

Description of key information

The surface tension of octan-1-ol is 35.5 mN/m at 25°C and ca. 90% saturated aqueous solution based on a reliable and well-reported published study.

n-Aliphatic alcohols consist of a lipophilic alkyl chain combined with a hydroxyl head group which is mildly hydrophilic. A preliminary assessment by calculated Hydrophilic Lipophilic Balance suggests the possibility to act as a water in oil emulsifier.

Key value for chemical safety assessment

Surface tension:

35.5

Additional information

The main purpose of determining surface tension is to assess whether a substance is a surfactant and not able to have a log K_ow done. n-Octanol is regularly used with water in the classic two-phase partitioning experiment (e.g. OECD Guideline 107). Octanol and all alcohols do phase separate which suggests that emulsification is not so strong as to create issues with measurement of partitioning or other fate or effects studies.

The reported measurement, for a highly pure sample, is at ca. 90% aqueous solution based on the limit of solubility of the highly pure alcohol as reported in the literature.

This result is supported by a second reliable measurement from the literature of 19.8 mN/m at 22.5°C and a slightly higher concentration of 440.8 mg/l.

Discussion of trends in the Category of C6-24 linear and essentially-linear aliphatic alcohols:

Chemical derivatives of many of the alcohols in this group are products which have commercial uses relating to their properties as surface active agents. The alcohols themselves are not surface active. Whilst the preliminary assessment by Hydrophilic Lipophilic Balance (HLB) suggests that the shortest chain members of the Category (C6 - C8) could be water/oil emulsifiers, this should not be over-interpreted. They are co-surfactants used to modify the properties of other surfactants.

Above C8 there is no alert based on HLB for any surface tension lowering property.