Zinc bis[O,O-bis(2-ethylhexyl)] bis(dithiophosphate)

Partition coefficient

Administrative data

Endpoint:

partition coefficient

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2010-06-13

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:

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
- Stability under test conditions: An OECD 111, 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. 9 mg/L at 22 degrees C.

Study design

Analytical method:

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

Results and discussion

Partition coefficient

Type:

log Pow

Partition coefficient:

3.59

Temp.:

22 °C

pH:

ca. 5

Details on results:

The partition coefficient (log Pow) was measured at 3 different Octanol / Water ratios in triplicate. Values for the partition coefficient lay between 3.12 and 3.78 with a mean value of 3.59 ± 0.22. Eight of the nine log Pow values fall within a range of ± 0.3 units, in agreement with the OECD 107 guideline for duplicate determination of Pow at three octanol/water ratios.

A mean mass balance (sample recovery) of 126 ± 12.9% was found. The reason for this higher than expected value is unclear. It is noted that a high mass balance is present for all ratios of octanol/water.

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 Octanolug/mL
2/1	1	7154	0.53	35584	1177	2220.75	3.35	4580.83	3.62	0.24
	2	2527	0.23	42362	1391	6047.83	3.78
	3	2542	0.23	38163	1259	5473.91	3.74
1/1	1	2640	0.24	34246	1134	4725.00	3.67	4516.27	3.65	0.02
	2	2655	0.24	32666	1084	4516.67	3.65
	3	3260	0.28	36512	1206	4307.14	3.63
1/2	1	14036	0.98	38814	1279	1305.10	3.12	3757.98	3.50	0.34
	2	2739	0.25	45664	1496	5984.00	3.78
	3	3975	0.33	39956	1315	3984.848	3.60
Overall Mean logPow									3.59
Standard Deviation in logPow									0.22

 

 

 

Table 8. Method Accuracy (% of nominal concentration)

Nominal Conc. (mg/L)	Total Areas	Dilution Factor	Concentration (mg/L)		% of Nominal
0.02	38530	1	0.25	123.8%
	37111	1	0.24	119.8%
	36194	1	0.23	117.3%
1.0	170042	1	0.96	95.7%
	200023	1	1.11	111.1%
	220856	1	1.22	121.6%
4.0	1332120	1	4.66	116.4%
	1315844	1	4.64	115.9%
	1267450	1	4.57	114.3%

Table 9. Sample Recoveries

Octanol/Water Ratio	Replicate	Aqueous Phase Mass (ug)	Octanol Phase Mass (ug)	Total Mass     (ug)	Initial Mass (ug)	%  Recovery	Mean % Recovery
2/1	1	1.6	7062	7063	6000	118	127.7
	2	0.7	8348	8349	6000	139
	3	0.7	7552	7553	6000	126
1/1	1	1.1	5105	5106	4500	113	114.0
	2	1.1	4879	4880	4500	108
	3	1.3	5429	5430	4500	121
1/2	1	5.9	3838	3844	3000	128	136.7
	2	1.5	4487	4488	3000	150
	3	2.0	3946	3948	3000	132
Mean % Recovery							126.1
Standard Deviation							13.1

Applicant's summary and conclusion

Conclusions:

Results of the study indicate the substance partitions primarily into the octanol phase with a logPow of 3.59.

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.   

 

Values for the partition coefficient lay between 3.12 - 3.78 with a mean logPow of 3.59.