Phosphorodithioic acid, O,O-bis(2-methylpropyl) ester, compd. with N,N-dimethylmethanamine (1:1)

Vapour pressure

Administrative data

Endpoint:

vapour pressure

Type of information:

experimental study

Adequacy of study:

key study

Study period:

July 10, 2012 - October 8, 2012

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2012

Report date:

2012

Materials and methods

Test guideline

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 104 (Vapour Pressure Curve)

Deviations:

yes

Remarks:

open aluminum pans were used under nitrogen purge at 25 mL/min. This is a discrepancy from the OECD guideline. The OECD guideline calls for a plate instead of a pan.

Principles of method if other than guideline:

The vapour pressure of the test substance was determined by an effusion method: isothermal thermogravimetry (TGA). The TGA method is based on the determination of accelerated evaporation rates for the test substance at elevated temperatures and ambient pressure. This method is suitable for substances with vapour pressures as low as 10E-10 Pa (10-12 mbar) and with purity as close as possible to 100% to avoid the misinterpretation of measured weight losses. The estimated repeatability is 10 to 30% and the estimated reproducibility is up to 50%. However, incorporating NIST traceable standard reference materials and open pans, the reproducibility and accuracy is much higher.

GLP compliance:

no

Remarks:

the test is well described; calibration using several standard materials was applied

Type of method:

effusion method: by loss of weight or by trapping vaporisate

Test material

Test material information

Constituent 1

Reference substance name:

O,O-bis(2-methylpropyl) sulfanidylphosphonothioate; trimethylazanium

EC Number:

700-910-4

Cas Number:

1354201-99-2

Molecular formula:

C11H28NO2PS2

IUPAC Name:

O,O-bis(2-methylpropyl) sulfanidylphosphonothioate; trimethylazanium

Test material form:

solid

Remarks:

pale yellow glassy solid

Specific details on test material used for the study:

- Name of test material (as cited in study report): S-10713
- Substance type: Straw color, lump solid
- Physical state: solid
- Lot/batch No.: AQ11216TZ
- Expiration date of the lot/batch: July 2013
- Stability: Stable under normal conditions
- Storage condition of test material: Room temperature; in the dark

Results and discussion

Vapour pressure

Vapour pressure 1

Temp.:

25 °C

Vapour pressure:

0.139 Pa

Vapour pressure 2

Temp.:

20 °C

Vapour pressure:

0.091 Pa

Any other information on results incl. tables

The vapour pressure equation with Pa units is: 

Y = -3193.5X + 9.8554 

where Y = log pressure (Pa), and X = 1/K. The R2 = 0.9992. 

Table. Experimental evaporation rates on the test substance and calculated vapor pressure.

Sample Temperature		Evaporation Rate		Calculated Vapor Pressure
°C	1/K	%wt./min	log %wt./min	log P (Pa)	P (Pa)
40	0.00319	0.0006271	-3.202663199	-0.3553	0.4413
60	0.00300	0.002601	-2.584859648	0.2970	1.9816
80	0.00283	0.008008	-2.096475936	0.8126	6.4959
100	0.00268	0.02151	-1.66735959	1.2657	18.4375
120	0.00254	0.06176	-1.209292713	1.7493	56.1473

The above equation was derived from the experimental evaporation rates of the test substance and standard reference material and the literature value of the standard reference material.

The log evaporation rates of the test substance was plugged into the equation Y = 1.0558X + 3.0261 in order to calculate the vapour pressure at the experimental temperature. Y = log pressure of benzoic acid (Pa) and X = log evaporation rate of benzoic acid (%wt./min.). The experimental evaporation rates of the test substance at five temperatures are given in the table here above. The corresponding TGA isotherms for the test substance are attached.

Applicant's summary and conclusion

Conclusions:

The estimated vapour pressure of the test substance at 20 °C is 0.0915 Pa and at 0.139 Pa at 25 °C. Both values were determined using a method based on OECD 104 guideline.

Executive summary:

The vapour pressure of the test material has been determined according to EC A.4 method and OECD test guideline 104.

The test material has been determined to have a vapour pressure of 0.0915 Pa at 20°C and 0.139 Pa at 25°C using the isothermal thermogravimetric effusion method.