Phosphorodithioic acid, mixed O,O-bis(iso-Bu and pentyl) esters, zinc salts

Partition coefficient

Administrative data

Endpoint:

partition coefficient

Type of information:

experimental study

Adequacy of study:

key study

Study period:

25 May 2010 - 28 May 2010

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: The study was performed according to guideline. The test substance was analytically monitored by a substance specific method. The test method was validated with respect to linearity and accuracy.

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(iso-Bu and pentyl) esters, zinc salts

EC Number:

270-608-0

EC Name:

Phosphorodithioic acid, mixed O,O-bis(iso-Bu and pentyl) esters, zinc salts

Cas Number:

68457-79-4

Molecular formula:

{[(iso-C4H9O)0.64(C5H11O)0.36]PS2}2Zn - neutral, {[(iso-C4H9O)0.64(C5H11O)0.36]PS2}6Zn4O - basic

IUPAC Name:

Phosphorodithioic acid, mixed O,O-bis(iso-Bu and pentyl) esters, zinc salts

Details on test material:

-Substance type: a coordination 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). At pH 9, the zinc metal was exchanged for the sodium of the buffer while the alkyldithiophosphate ligand remained intact.
-Other: The water solubility of the substance was determined to be approx. 1600 mg/L at 22 degrees C.

Study design

Analytical method:

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

Results and discussion

Partition coefficient

Type:

log Pow

Partition coefficient:

0.69

Temp.:

21.8 °C

pH:

ca. 5

Details on results:

Values for logPow were between 0.48 and 0.84 with a mean value of 0.69 (± 0.12). Sample recovery was 93.6% (± 10.6%).

The compositions of the aqueous and octanol phases were compared by GC (gas chromatography following derivatization). GC chromatograms obtained for the water and octanol phases show differences in the distribution of ZDDP components between the phases. The concentration of ZDDPs containing dialkyldithiophosphate ligands where the alkyl chain is C4 (isobutyl) is proportionately higher in the aqueous phase. The octanol phase contains higher concentrations of dialkyldithiophosphates containing C5 (pentyl isomers ) and mixtures of C4/C5 alkyl groups.

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	133923	186.14	15244	713.5	3.83	0.58	3.79	0.57	0.09
	2	202416	257.21	17092	783.3	3.05	0.48
	3	128371	179.74	17698	806	4.48	0.65
1/1	1	108177	155.66	15164	710.5	4.56	0.66	5.25	0.71	0.11
	2	85893	127.62	19579	876.7	6.87	0.84
	3	123602	174.17	16255	751.7	4.32	0.64
1/2	1	95216	139.54	20307	903.9	6.48	0.81	6.17	0.79	0.05
	2	65511	100.63	13977	665.6	6.61	0.82
	3	86599	128.54	14785	696.2	5.42	0.73
Overall Mean logPow									0.69
Standard Deviation in logPow									0.12

     

 

 

Table 8. Method Accuracy (% of nominal concentration)

Nominal (mg/L)	Sum Peak Areas	Dilution	Conc.        (mg/L)	% Recovery
0.2	15799	1	0.15	73.40%
0.2	20385	1	0.18	90.70%
0.2	20756	1	0.18	92.10%
Mean				85.40%
SD				10.40%
%RSD				12.1
1.0	177973	1	1.17	116.80%
1.0	196732	1	1.26	125.90%
1.0	186035	1	1.21	120.80%
Mean				121.20%
SD				4.60%
%RSD				3.8

Table 9.  Sample Recoveries

Octanol/Water Ratio	Replicate	Aqueous Phase Mass  (ug)	Octanol Phase Mass (ug)	Total Mass  (ug)	InitialMass (ug)	% Recovery
2/1	1	558	4281	4840	6000	81
	2	772	4700	5471	6000	91
	3	539	4836	5376	6000	90
1/1	1	700	3197	3898	4500	87
	2	574	3945	4519	4500	100
	3	784	3383	4166	4500	93
1/2	1	837	2712	3549	3000	118
	2	604	1997	2600	3000	87
	3	771	2089	2860	3000	95
				Mean % Recovery		93 %
				SD		10.6
				%RSD		11.6

Applicant's summary and conclusion

Conclusions:

The partition coefficient, logPow , of the substance is 0.69. ZDDP (zinc dialkyldithiophosphate) components partition between the phases depending on the alkyl chain length/molecular weight of the dialkyldithiophosphate ligands.

Executive summary:

Partitioning of the test substance between n-octanol and water was performed by the shake flask method according 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 ZDDPs (zinc dialkyldithiophosphates) in each phase was determined by GC-MS following derivatization. Aliquots from each phase were reacted with pentafluorobenzyl bromide to form halogenated dithiophosphate 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" Journal of Chromatography A. 905 (2001) 207-222.   

 

The following partition coefficient values were determined: Pow = 5.07   and logPow = 0.69