Phosphorodithioic acid, mixed O,O-bis(2-ethylhexyl and iso-Pr) esters, zinc salts

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

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 areas to determine any significant loss of components.

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

Test material information

Constituent 1

Reference substance name:

Phosphorodithioic acid, mixed O,O-bis(2-ethylhexyl and iso-Pr) esters, zinc salts

EC Number:

272-723-1

EC Name:

Phosphorodithioic acid, mixed O,O-bis(2-ethylhexyl and iso-Pr) esters, zinc salts

Cas Number:

68909-93-3

Molecular formula:

Too complex

IUPAC Name:

Phosphorodithioic acid, mixed O,O-bis(2-ethylhexyl and iso-Pr) esters, zinc salts

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 tables below shows < 10% change in the concentration of the test substance and in the GC peak area percents of individual component after a 24 hour storage in n-octanol at 22 deg. C

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

Time (hours)	Sum GC Peak Areas	mg/L
0	23072	793
24	21096	732
% difference in concentration after 24 hours		-7.7 %

GC Peak Area % of Components in Substance After Storage in n-Octanol (24 hours at 22 C)

GC Peak	1	2	3	4	5	6
Peak Retention time (min)	8.16	10.68	10.84	13.44	13.55	13.65
0 hours	22.11%	29.87%	33.37%	3.21%	7.92%	3.53%
24 hours	22.88%	29.35%	31.89%	3.52%	8.62%	3.74%

GC chromatorams are attached as Figure 1

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 criterion for stability was < 10% change in concentration of the substance or differences in the peak area per cents of the individual components.

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.