Registration Dossier

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 guidelineopen allclose all
Qualifier:
according to guideline
Guideline:
OECD Guideline 107 (Partition Coefficient (n-octanol / water), Shake Flask Method)
Deviations:
no
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

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
- 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.