Phosphorodithioic acid, mixed O,O-bis(1,3-dimethylbutyl and iso-Pr) esters, zinc salts

Partition coefficient

Administrative data

Endpoint:

partition coefficient

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2010

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: The study was performed according to guideline under GLP conditions. The test substance was analytical monitored by a substance specific method. The analytical method was validated with respect to linearity and precision

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2010

Report date:

2010

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

OECD Guideline 107 (Partition Coefficient (n-octanol / water), Shake Flask Method)

Deviations:

no

Test guideline 2

Qualifier:

equivalent or similar to guideline

Guideline:

other: Publication: "Structural determination of zinc dithiophosphates in lubricating oils by gas chromatography-mass spectrometry with electron impact and electron-capture negative ion chemical ionization" Journal of Chromatography A. 905 (2001) 207-222.

Deviations:

not applicable

GLP compliance:

yes

Type of method:

shake-flask method to: flask method

Partition coefficient type:

octanol-water

Test material

Test material information

Constituent 1

Reference substance name:

Phosphorodithioic acid, mixed O,O-bis(1,3-dimethylbutyl and iso-Pr) esters, zinc salts

EC Number:

283-392-8

EC Name:

Phosphorodithioic acid, mixed O,O-bis(1,3-dimethylbutyl and iso-Pr) esters, zinc salts

Cas Number:

84605-29-8

Molecular formula:

Not applicable

IUPAC Name:

Phosphorodithioic acid, mixed O,O-bis(1,3-dimethylbutyl and iso-Pr) esters, zinc salts

Details on test material:

-Substance type: is a mixture of coordinations compound consisting of a zinc metal complex bonded to dialkyldithiophosphate ligands.
- Stability under test conditions: A Tier 1, preliminary hydrolysis studies conducted on the substance at 50 deg. C and pH 4, 7 and 9, indicated the dialkyl dithiophosphate ligands are hydrolytically stable ( <10% change in concentration of dialkyldithiophosphate ligand).

Study design

Analytical method:

other: GC-MS (gas chromatography-mass spectrometry)

Results and discussion

Partition coefficient

Type:

log Pow

Partition coefficient:

0.56

Temp.:

22 °C

pH:

ca. 5

Details on results:

Values for logPow were between 0.21 and 0.98 with a mean value of 0.56 ( ± 0.26). Sample recovery was 63.6 % (± 19.5%).

The compositions of the aqueous and octanol phases were compared by GC (gas chromatography on derivatized substance). The chromatograms show ZDDP (zinc dialkyldithiophosphate) components were distributed between both phases with a higher proportion of lower molecular weight dithiophosphate ligands containing the C3 (isopropyl) alkyl group (peak eluting at 8.17 min) in the aqueous phase. The chromatogram of the octanol phases shows a higher proportion of the higher molecular weight dithiophosphate ligands containing all C6 (1,3-dimethyl butyl) and ligands containing a mixture of C3/C6 alkyl chains.

Any other information on results incl. tables

Table 7. Results of Partition Coefficient Test

 

Octanol/Water Ratio	Replicate	Aqueous Phase		Octanol Phase		Pow	logPow	Mean  Pow	Mean logPow	Std Dev logPow
		Sum GC Peak Areas	Conc in Water ug/mL)	Sum GC Peak Areas	Conc in Octanol (ug/mL)
2/1	1	140800	174	19634	686	3.94	0.60	3.34	0.51	0.16
	2	191368	231	13068	479	2.08	0.32
	3	87329	111	11923	443	3.99	0.60
1/1	1	359065	409	18987	665	1.63	0.21	2.17	0.32	0.16
	2	109864	137	9588	370	2.70	0.43
	3	284803	333	9286	360	*1.08	*0.03
1/2	1	45639	60	9385	363	6.05	0.78	7.33	0.85	0.11
	2	59946	77	13443	491	6.38	0.80
	3	29218	39	9673	372	9.55	0.98
Overall Mean logPow									0.56
Standard Deviation in logPow									0.26

Table 8. Method Accuracy (% of nominal concentration)

Nominal (mg/L)	SumAreas	Dilution	Conc.        (mg/L)	% Recovery
0.2	13943	1	0.09	50.70%
0.2	28351	1	0.19	95.80%
0.2	17176	1	0.12	60.90%
Mean				69.10%
SD				23.70%
%RSD				34.3
1.00	147628	1	0.95	90.80%
1.00	137278	1	0.89	84.80%
1.00	182920	1	1.16	111.00%
Mean				95.60%
SD				13.70%
%RSD				14.3
4.00	927012	1	4.38	105.90%
4.00	1071352	1	4.72	114.80%
4.00	1105295	1	4.79	116.70%
Mean				112.50%
SD				5.80%
%RSD				5.1

Table 9. Sample Recovery

Octanol/Water Ratio	Replicate	Aqueous Phase Mass (ug)	Octanol Phase Mass (ug)	Total Mass     (ug)	Initial Mass (ug)	%  Recovery	Mean % Recovery
2/1	1	521	4114	4636	6000	77	62.3
	2	694	2876	3570	6000	60
	3	332	2660	2991	6000	50
1/1	1	1839	2994	4833	4500	107	75.7
	2	619	1663	2282	4500	51
	3	1498	1620	3118	4500	69
1/2	1	359	1090	1448	3000	48	52.7
	2	464	1473	1938	3000	65
	3	237	1117	1353	3000	45
Mean % Recovery							63.6
Standard Deviation							19.5

Applicant's summary and conclusion

Conclusions:

The test substance has a partition coefficient value, logPow, of 0.56 ± 0.26. The distribution of this multicomponent substance between the organic and aqueous phases is dependent on the alkyl chain lengths of the alkyldithiophosphate ligands

Executive summary:

Partitioning of the test substance between n-octanol and water was performed by the shake flask method equivalent to OECD 107. Test mixtures were prepared in triplicate under three different conditions where the octanol/water volume ratios were varied ( 1/2 , 2/1, and 1/1). Test mixtures were shaken for 5 min at 22 degrees C and the n-octanol and water phases separated by centrifugation. 

 

The concentration of ZDDP in each phase was determined by GC-MS following reaction with pentafluorobenzyl bromide to form halogenated derivatives according to a 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.   

 

The following partition coefficient values were determined: Pow = 4.54   and logPow = 0.56.