Tall oil, maleated

Vapour pressure

Link to relevant study record(s)

Reference

Endpoint:

vapour pressure

Type of information:

experimental study

Adequacy of study:

key study

Study period:

Initiation: September 24, 2013 Completion May 20, 2014

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 104 (Vapour Pressure Curve)

Version / remarks:

Specifically: The Effusion Method – modified amalgamation of the Knudsen Cell and Isothermal Thermogravity Methods.

GLP compliance:

yes (incl. QA statement)

Type of method:

other: modified amalgamation of the Knudsen Cell and Isothermal Thermogravity Methods.

Key result

Test no.:

#1

Temp.:

36.1 °C

Remarks on result:

not determinable

Remarks:

The evaporation rate was observed to be less than that of the hexadecane standard

Key result

Test no.:

#2

Temp.:

49.5 °C

Remarks on result:

not determinable

Remarks:

The evaporation rate was observed to be less than that of the hexadecane standard

Key result

Test no.:

#3

Temp.:

58.3 °C

Remarks on result:

not determinable

Remarks:

The evaporation rate was observed to be less than that of the hexadecane standard

The results show that the test item gained approximately 1 mg in weight during the incubation under vacuum. This implies that there is no measurable vapour pressure under the conditions used.

The weight change was observed to be less than that of the reference standards naphthalene and hexadecane, of which hexadecane has the lowest vapour pressure.

In order to verify that the Knudsen cell and naphthalene calibration was operating normally, the vapour pressure of hexadecane was calculated and compared to literature values. The measured value at 58.3 °C, the only temperature at which a useable value was obtained, was found to be 103.3 % of the expected. Based on this result we concluded that the analytical system was operating normally. The weight change in the blank cells over the course of the incubations was less than 1 mg, while the error in the analytical balance was <0.0002 g.

Based on the results of our test, we conclude that the vapour pressure of the test item is less than that of hexadecane or <0.31 Pa at 25 ° C, and <0.19 Pa at 20 ° C.

Conclusions:

Based on the results of our test, we conclude that the vapour pressure of the test item is less than that of hexadecane or < 0.31 Pa at 25 °C, and <0.19 Pa at 20 °C.

Executive summary:

The vapour pressure of test item tall oil, maleated, was determined according to OECD Guideline for the Testing of Chemicals. Test No. 104: Vapour Pressure. March 23, 2006. Specifically: The Effusion Method – modified amalgamation of the Knudsen Cell and Isothermal Thermogravity Methods.

The measurements were based on the Knudsen and Isothermal Effusion Methods, described in OECD Test No. 104 (Sections 26, 27, 32, 33 and 34). These methods reportedly have a useful range from 10E-10 to 1 Pa, however ISI has shown that a modified Knudsen cell can be usefully calibrated up to 70 kPa. The Effusion method is based on the loss of weight from the test item and is limited by the sensitivity of the balance and the temperature to which the cells can be heated. The Gas Saturation method, which also operates in the low Pa range, was not useable because of the difficulty in establishing an analytical method with a sufficiently low detection limit.

The adapted Knudsen Cell Effusion method employed a 20 mL glass vial fitted with a septum cap, punctured with a 26G needle. Eight vials were filled with samples and standards as follows: 2 vials with 5 grams of the test sample, 2 vials with 2 grams of naphthalene standard, 2 vials with 4 mL of the hexadecane standard and 2 vials empty (blanks). The vials were capped and placed in a vacuum oven under 20 inches of mercury until a significant weight loss was detectable in a naphthalene standard, typically 40 to 120 hours The weight loss was determined by gravimetry.

Two independent preparations of the test item were run at each temperature, along with blanks and standards.

Temperatures ranging from 36 to 58 °C were used. The temperature was monitored using a calibrated thermocouple with its probe placed inside a shallow steel dish which held the Knudsen cells, visible through the window. Calibration standards, blanks and at least two independent preparations of test item were run at three temperatures.

The results show that the test item gained approximately 1 mg in weight during the incubation under vacuum. This implies that there is no measurable vapour pressure under the conditions used.

The weight change was observed to be less than that of the reference standards naphthalene and hexadecane, of which hexadecane has the lowest vapour pressure.

In order to verify that the Knudsen cell and naphthalene calibration was operating normally, the vapour pressure of hexadecane was calculated and compared to literature values. The measured value at 58.3 °C, the only temperature at which a useable value was obtained, was found to be 103.3% of the expected. Based on this result we concluded that the analytical system was operating normally. The weight change in the blank cells over the course of the incubations was less than 1 mg, while the error in the analytical balance was <0.0002 g.

Based on the results of our test, we conclude that the vapour pressure of the test item is less than that of hexadecane or <0.31 Pa at 25 °C, and <0.19 Pa at 20 °C.

Description of key information

The vapour pressure of the test item is less than that of hexadecane or <0.31 Pa at 25 °C, and <0.19 Pa at 20 °C.

Key value for chemical safety assessment

Vapour pressure:

0.19 Pa

at the temperature of:

20 °C