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Physical & Chemical properties

Stability in organic solvents and identity of relevant degradation products

Administrative data

Endpoint:
stability in organic solvents and identity of relevant degradation products
Type of information:
experimental study
Adequacy of study:
key study
Study period:
2010
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: No guideline available. The study was performed according to a substance specific method.

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2010
Report date:
2010

Materials and methods

Test guideline
Qualifier:
no guideline available
Deviations:
not applicable
Principles of method if other than guideline:
The stability of the test substance in n-octanol is determined by comparing GC chromatograms of a freshly prepared solution of the substance to a solution of the substance in n-octanol stored for a period of 24 hours at 22 deg. C. The storage conditions reproduce the conditions under which the substance was in contact with the solvent during OECD 107 partition coefficient testing.

Chromatograms are obtained following derivatization of the substance according to procedure described in the publication: "Structural determination of zinc dithiophosphates in lubricating oils by gas chromatography-mass spectrometry with electron impact and electron-capture negative ion chemical ionization" in Journal of Chromatography A. 905 (2001) 207-222.

Chromatograms are compared both qualitatively (by retention times of eluted peaks) and quantitatively (on the basis of peak area % ) to determine any significant changes to the substance.

Results of a GC analysis are used as the basis for determining the suitability of the shake flask method in determining the partition coefficient of the substance. A deviation of > 10% in the concentration of the substance or a significant change in the GC chromagograms between t= 0 and t=24 hours is used as the criterion for evaluating stability
GLP compliance:
yes

Test material

Constituent 1
Chemical structure
Reference substance name:
Zinc bis[O,O-bis(2-ethylhexyl)] bis(dithiophosphate)
EC Number:
224-235-5
EC Name:
Zinc bis[O,O-bis(2-ethylhexyl)] bis(dithiophosphate)
Cas Number:
4259-15-8
Molecular formula:
Too complex
IUPAC Name:
1-Hexanol, 2-ethyl-, O,O-diester with phosphorodithioic acid, zinc salt
Details on test material:
-Substance type: a coordination compound consisting of a zinc metal complex bonded to dialkyldithiophosphate ligands

Results and discussion

Test substance stable:
yes
Transformation products:
no

Any other information on results incl. tables

The GC chromatogram of the test substance after a 24 hour storage in n-octanol at 22 deg. shows no changes in composition

that could be attributed to degradation of the substance. The GC peak area % of the single component, representative of the test substance, in the t = 24 hour chromatogram shows a 24% increase. This value represents the deviation in the GC method.

GC chromatorams comparing the substance at t = 0 and t = 24 hours are attached as Figure 1

Table 1. Stability of Test Substance in n-Octanol (24 hours at 22 C)

Time (hours)

Sum GC Peak Areas

Conc. of test substance (mg/L)

0

39152

1290

24

48983

1600

% difference in concentration after 24 hours

+ 24

Applicant's summary and conclusion

Conclusions:
GC-MS analyses indicate the substance is stable in n-octanol when in contact with this organic solvent for a period of 24 hours at 22 deg. C and the shake flask method is suitable for the determination of the partition coefficient of this substance.
Executive summary:

The stability of the test substance in n-octanol is determined by comparing a freshly prepared solution of the substance to a solution of the substance in n-octanol stored for a period of 24 hours at 22 deg. C. The storage conditions reproduce the conditions under which the substance was in contact with the solvent during OECD 107 partition coefficient testing.

The compositions of the substance at t = 0 and t = 24 hours were compared by GC -MS following derivatization to halogenated derivatives with pentafluorobenzyl bromide (CASRN 1765-40-8). The derivatization process produces pentafluorobenzyl-phosphorodithioic acid molecules more amenable to GC separation than the starting zinc dialkyldithiophosphate complex.

Chromatograms were compared both qualitatively (by retention times of eluted peaks) and quantitatively on the basis of peak areas (which are proportional to the amount of a component) to determine any significant losses due to contact with n-octanol.

Results of the analysis indicate the substance is stable in n-octanol for the duration of the OECD 107 partition coefficient study by the shake flask method. The evaluation for stability was based on the qualitative comparison of GC chromatograms of the substance at t = 0 and t = 24 hours storage in n-octanol.

The stability of the substance was not evaluated in other solvents as it is not stored in other organic solvents prior to testing for other physico-chemical properties.